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Harry L. T. Mobley - One of the best experts on this subject based on the ideXlab platform.
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oxygen limiting conditions enrich for fimbriate cells of uropathogenic proteus mirabilis and escherichia coli
Journal of Bacteriology, 2009Co-Authors: Chelsea M Lane, Melanie M Pearso, Amy N Simms, Harry L. T. MobleyAbstract:MR/P fimbriae of uropathogenic Proteus mirabilis undergo Invertible Element-mediated phase variation whereby an individual bacterium switches between expressing fimbriae (phase ON) and not expressing fimbriae (phase OFF). Under different conditions, the percentage of fimbriate bacteria within a population varies and could be dictated by either selection (growth advantage of one phase) or signaling (preferentially converting one phase to the other in response to external signals). Expression of MR/P fimbriae increases in a cell-density dependent manner in vitro and in vivo. However, rather than the increased cell density itself, this increase in fimbrial expression is due to an enrichment of fimbriate bacteria under oxygen limitation resulting from increased cell density. Our data also indicate that the persistence of MR/P fimbriate bacteria under oxygen-limiting conditions is a result of both selection (of MR/P fimbrial phase variants) and signaling (via modulation of expression of the MrpI recombinase). Furthermore, the mrpJ transcriptional regulator encoded within the mrp operon contributes to phase switching. Type 1 fimbriae of Escherichia coli, which are likewise subject to phase variation via an Invertible Element, also increase in expression during reduced oxygenation. These findings provide evidence to support a mechanism for persistence of fimbriate bacteria under oxygen limitation, which is relevant to disease progression within the oxygen-restricted urinary tract.
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identification of mrpi as the sole recombinase that regulates the phase variation of mr p fimbria a bladder colonization factor of uropathogenic proteus mirabilis
Molecular Microbiology, 2002Co-Authors: Xin Li, David E Johnson, Virginia C Lockatell, Harry L. T. MobleyAbstract:Summary Proteus mirabilis is a common cause of urinary tract infection (UTI) in individuals with structural abnormalities or long-term catheterization. The expression of mannose-resistant/ Proteus -like (MR/P) fimbria is phase variable because of the inversion of a 251 bp DNA fragment that carries the promoter for the mrp operon. Previous studies have shown that mrpI , which is transcribed divergently from the mrp operon, encodes a recombinase capable of switching the orientation of this Invertible Element. In this study, we constructed isogenic mrpI null mutants from a clinical isolate of P. mirabilis , HI4320. A polymerase chain reaction (PCR)-based Invertible Element assay revealed that the isogenic mrpI null mutants were locked in one phase, either expressing (locked on) MR/P fimbriae or not (locked off), which indicated that MrpI was the sole recombinase that regulated the phase variation of MR/P fimbria. The locked-on and locked-off mutants were evaluated for virulence in the CBA mouse model of ascending UTI by co-challenges with each other and with the wild-type strain. Results from these experiments demonstrated conclusively that the MR/P fimbria was a critical bladder colonization factor of uropathogenic P. mirabilis and also suggested that the ability to switch off the expression of MR/P fimbria might be important for kidney colonization.
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assessment of virulence of uropathogenic escherichia coli type 1 fimbrial mutants in which the Invertible Element is phase locked on or off
Infection and Immunity, 2002Co-Authors: Nereus W Gunther, David E Johnson, Virginia C Lockatell, Jennifer A Snyder, Ian C Blomfield, Harry L. T. MobleyAbstract:Type 1 fimbria is a proven virulence factor of uropathogenic Escherichia coli (UPEC), causing urinary tract infections. Expression of the fimbria is regulated at the transcriptional level by a promoter situated on an Invertible Element, which can exist in one of two different orientations. The orientation of the Invertible Element that allows the expression of type 1 fimbriae is defined as “on,” and the opposite orientation, in which no transcription occurs, is defined as “off.” During the course of a urinary tract infection, we have observed that the infecting E. coli population alternates between fimbriated and nonfimbriated states, with the fimbriated on orientation peaking at 24 h. We propose that the ability of the Invertible Element to switch orientations during infection is itself a virulence trait. To test this hypothesis, nucleotide sequence changes were introduced in the left inverted repeat of the Invertible Element of UPEC pyelonephritis strain CFT073 that locked the Invertible Elements permanently in either the on or the off orientation. The virulence of these mutants was assessed in the CBA mouse model of ascending urinary tract infection at 4, 24, 48, and 72 h postinoculation (hpi). We conducted independent challenges, in which bladders of mice were inoculated with either a single mutant or the wild type, and cochallenges, in which a mutant and the wild type were inoculated together to allow direct competition in the urinary tract. In both sets of experimental infections, the locked-off mutant was recovered from the urine, bladder, and kidneys in significantly lower numbers than the wild type at 24 hpi (P ≤ 0.05), demonstrating its attenuation. Conversely, the locked-on mutant was recovered in higher numbers than the wild type at 24 hpi (P ≤ 0.05), showing enhanced virulence of this mutant. No significant differences were seen between the mutants and wild type in the urine or the bladder at 48 or 72 hpi. However, the wild type outcompeted the locked-off mutant in the kidneys during the cochallenge experiment at 72 hpi (P = 0.009). Overall, these data suggest that the ability of the Invertible Element controlling type 1 fimbria expression to phase vary contributes significantly to virulence early (24 hpi) in the course of a urinary tract infection by UPEC and most profoundly influences colonization of the bladder.
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in vivo dynamics of type 1 fimbria regulation in uropathogenic escherichia coli during experimental urinary tract infection
Infection and Immunity, 2001Co-Authors: Nereus W Gunther, David E Johnson, Virginia C Lockatell, Harry L. T. MobleyAbstract:Escherichia coli is the primary cause of uncomplicated infections of the urinary tract including cystitis. More serious infections, characterized as acute pyelonephritis, can also develop. Type 1 fimbriae of E. coli contribute to virulence in the urinary tract; however, only recently has the expression of the type 1 fimbriae been investigated in vivo using molecular techniques. Transcription of type 1 fimbrial genes is controlled by a promoter that resides on a 314-bp Invertible Element capable of two orientations. One places the promoter in the ON orientation, allowing for transcription; the other places the promoter in the OFF orientation, preventing transcription. A PCR-based assay was developed to measure the orientation of the Invertible Element during an experimental urinary tract infection in mice. Using this assay, it was found that the percentage of the population ON in urine samples correlated with the respective CFU per gram of bladder (P = 0.0006) but not with CFU per gram of kidney (P > 0.069). Cystitis isolates present in the urine of mice during the course of infection had a higher percentage of their Invertible Elements in the ON orientation than did pyelonephritis isolates (85 and 34%, respectively, at 24 h; P < 0.0001). In general, cystitis isolates, unlike pyelonephritis isolates, were more likely to maintain their Invertible Elements in the ON orientation for the entire period of infection. E. coli cells expressing type 1 fimbriae, expelled in urine, were shown by scanning electron microscopy to be densely packed on the surface of uroepithelial cells. These results suggest that expression of type 1 fimbriae is more critical for cystitis strains than for pyelonephritis strains in the early stages of an infection during bladder colonization.
Eric J Battaglioli - One of the best experts on this subject based on the ideXlab platform.
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identification and characterization of a phase variable Element that regulates the autotransporter upae in uropathogenic escherichia coli
Mbio, 2018Co-Authors: Eric J Battaglioli, Kelvin G K Goh, Tensin S Atruksang, Kevin J Schwartz, Mark A Schembri, Rodney A WelchAbstract:ABSTRACT Uropathogenic Escherichia coli (UPEC) is the most common etiologic agent of uncomplicated urinary tract infection (UTI). An important mechanism of gene regulation in UPEC is phase variation that involves inversion of a promoter-containing DNA Element via enzymatic activity of tyrosine recombinases, resulting in biphasic, ON or OFF expression of target genes. The UPEC reference strain CFT073 has five tyrosine site-specific recombinases that function at two previously characterized promoter inversion systems, fimS and hyxS. Three of the five recombinases are located proximally to their cognate target Elements, which is typical of promoter inversion systems. The genes for the other two recombinases, IpuA and IpuB, are located distal from these sites. Here, we identified and characterized a third phase-variable Invertible Element in CFT073, ipuS, located proximal to ipuA and ipuB. The inversion of ipuS is catalyzed by four of the five CFT073 recombinases. Orientation of the Element drives transcription of a two-gene operon containing ipuR, a predicted LuxR-type regulator, and upaE, a predicted autotransporter. We show that the predicted autotransporter UpaE is surface located and facilitates biofilm formation as well as adhesion to extracellular matrix proteins in a K-12 recombinant background. Consistent with this phenotype, the ipuS ON condition in CFT073 results in defective swimming motility, increased adherence to human kidney epithelial cells, and a positive competitive kidney colonization advantage in experimental mouse UTIs. Overall, the identification of a third phase switch in UPEC that is regulated by a shared set of recombinases describes a complex phase-variable virulence network in UPEC. IMPORTANCE Uropathogenic Escherichia coli (UPEC) is the most common cause of urinary tract infection (UTI). ON versus OFF phase switching by inversion of small DNA Elements at two chromosome sites in UPEC regulates the expression of important virulence factors, including the type 1 fimbria adhesion organelle. In this report, we describe a third Invertible Element, ipuS, in the UPEC reference strain CFT073. The inversion of ipuS controls the phase-variable expression of upaE, an autotransporter gene that encodes a surface protein involved in adherence to extracellular matrix proteins and colonization of the kidneys in a murine model of UTI.
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identification and characterization of a phase variable Element that regulates the autotransporter upae in uropathogenic escherichia coli
bioRxiv, 2018Co-Authors: Rodney A Welch, Kelvin G K Goh, Tensin S Atruksang, Kevin J Schwartz, Mark A Schembri, Eric J BattaglioliAbstract:Uropathogenic Escherichia coli (UPEC) are the most common etiological agent of uncomplicated urinary tract infection (UTI). An important mechanism of gene regulation in UPEC is phase variation that involves inversion of a promoter-containing DNA Element via enzymatic activity of tyrosine recombinases, resulting in biphasic, ON or OFF expression of target genes. The UPEC reference strain CFT073 has five tyrosine site-specific recombinases that function at two previously characterized promoter inversion systems, fimS and hyxS. Three of the five recombinases are located proximally to their cognate target Elements, which is typical of promoter inversion systems. The genes for the other two recombinases, IpuA and IpuB are located distal from these sites. Here, we identified and characterized a third phase variable Invertible Element in CFT073, ipuS located proximal to ipuA and ipuB. The inversion of ipuS is catalyzed by four of the five CFT073 recombinases. Orientation of the Element drives transcription of a two-gene operon containing ipuR, a predicted LuxR-type regulator, and upaE, a predicted autotransporter. We show that the predicted autotransporter UpaE is surface-located and facilitates biofilm formation as well as adhesion to extracellular matrix proteins in a K-12 recombinant background. Consistent with this phenotype, the ipuS ON condition in CFT073 results in defective swimming motility, increased adherence to human kidney epithelial cells, and a positive competitive kidney colonization advantage in experimental mouse UTI infections. Overall, the identification of a third phase-switch in UPEC that is regulated by a shared set of recombinases describes a complex phase-variable virulence network in UPEC.
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Identification and Characterization of a Phase-Variable Element That Regulates the Autotransporter UpaE in Uropathogenic Escherichia coli
'American Society for Microbiology', 2018Co-Authors: Eric J Battaglioli, Kelvin G K Goh, Mark A Schembri, T. S. Atruktsang, K. Schwartz, Rodney A WelchAbstract:Uropathogenic Escherichia coli (UPEC) is the most common etiologic agent of uncomplicated urinary tract infection (UTI). An important mechanism of gene regulation in UPEC is phase variation that involves inversion of a promoter-containing DNA Element via enzymatic activity of tyrosine recombinases, resulting in biphasic, ON or OFF expression of target genes. The UPEC reference strain CFT073 has five tyrosine site-specific recombinases that function at two previously characterized promoter inversion systems, fimS and hyxS. Three of the five recombinases are located proximally to their cognate target Elements, which is typical of promoter inversion systems. The genes for the other two recombinases, IpuA and IpuB, are located distal from these sites. Here, we identified and characterized a third phase-variable Invertible Element in CFT073, ipuS, located proximal to ipuA and ipuB. The inversion of ipuS is catalyzed by four of the five CFT073 recombinases. Orientation of the Element drives transcription of a two-gene operon containing ipuR, a predicted LuxR-type regulator, and upaE, a predicted autotransporter. We show that the predicted autotransporter UpaE is surface located and facilitates biofilm formation as well as adhesion to extracellular matrix proteins in a K-12 recombinant background. Consistent with this phenotype, the ipuS ON condition in CFT073 results in defective swimming motility, increased adherence to human kidney epithelial cells, and a positive competitive kidney colonization advantage in experimental mouse UTIs. Overall, the identification of a third phase switch in UPEC that is regulated by a shared set of recombinases describes a complex phase-variable virulence network in UPEC.Uropathogenic Escherichia coli (UPEC) is the most common cause of urinary tract infection (UTI). ON versus OFF phase switching by inversion of small DNA Elements at two chromosome sites in UPEC regulates the expression of important virulence factors, including the type 1 fimbria adhesion organelle. In this report, we describe a third Invertible Element, ipuS, in the UPEC reference strain CFT073. The inversion of ipuS controls the phase-variable expression of upaE, an autotransporter gene that encodes a surface protein involved in adherence to extracellular matrix proteins and colonization of the kidneys in a murine model of UTI
David E Johnson - One of the best experts on this subject based on the ideXlab platform.
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identification of mrpi as the sole recombinase that regulates the phase variation of mr p fimbria a bladder colonization factor of uropathogenic proteus mirabilis
Molecular Microbiology, 2002Co-Authors: Xin Li, David E Johnson, Virginia C Lockatell, Harry L. T. MobleyAbstract:Summary Proteus mirabilis is a common cause of urinary tract infection (UTI) in individuals with structural abnormalities or long-term catheterization. The expression of mannose-resistant/ Proteus -like (MR/P) fimbria is phase variable because of the inversion of a 251 bp DNA fragment that carries the promoter for the mrp operon. Previous studies have shown that mrpI , which is transcribed divergently from the mrp operon, encodes a recombinase capable of switching the orientation of this Invertible Element. In this study, we constructed isogenic mrpI null mutants from a clinical isolate of P. mirabilis , HI4320. A polymerase chain reaction (PCR)-based Invertible Element assay revealed that the isogenic mrpI null mutants were locked in one phase, either expressing (locked on) MR/P fimbriae or not (locked off), which indicated that MrpI was the sole recombinase that regulated the phase variation of MR/P fimbria. The locked-on and locked-off mutants were evaluated for virulence in the CBA mouse model of ascending UTI by co-challenges with each other and with the wild-type strain. Results from these experiments demonstrated conclusively that the MR/P fimbria was a critical bladder colonization factor of uropathogenic P. mirabilis and also suggested that the ability to switch off the expression of MR/P fimbria might be important for kidney colonization.
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assessment of virulence of uropathogenic escherichia coli type 1 fimbrial mutants in which the Invertible Element is phase locked on or off
Infection and Immunity, 2002Co-Authors: Nereus W Gunther, David E Johnson, Virginia C Lockatell, Jennifer A Snyder, Ian C Blomfield, Harry L. T. MobleyAbstract:Type 1 fimbria is a proven virulence factor of uropathogenic Escherichia coli (UPEC), causing urinary tract infections. Expression of the fimbria is regulated at the transcriptional level by a promoter situated on an Invertible Element, which can exist in one of two different orientations. The orientation of the Invertible Element that allows the expression of type 1 fimbriae is defined as “on,” and the opposite orientation, in which no transcription occurs, is defined as “off.” During the course of a urinary tract infection, we have observed that the infecting E. coli population alternates between fimbriated and nonfimbriated states, with the fimbriated on orientation peaking at 24 h. We propose that the ability of the Invertible Element to switch orientations during infection is itself a virulence trait. To test this hypothesis, nucleotide sequence changes were introduced in the left inverted repeat of the Invertible Element of UPEC pyelonephritis strain CFT073 that locked the Invertible Elements permanently in either the on or the off orientation. The virulence of these mutants was assessed in the CBA mouse model of ascending urinary tract infection at 4, 24, 48, and 72 h postinoculation (hpi). We conducted independent challenges, in which bladders of mice were inoculated with either a single mutant or the wild type, and cochallenges, in which a mutant and the wild type were inoculated together to allow direct competition in the urinary tract. In both sets of experimental infections, the locked-off mutant was recovered from the urine, bladder, and kidneys in significantly lower numbers than the wild type at 24 hpi (P ≤ 0.05), demonstrating its attenuation. Conversely, the locked-on mutant was recovered in higher numbers than the wild type at 24 hpi (P ≤ 0.05), showing enhanced virulence of this mutant. No significant differences were seen between the mutants and wild type in the urine or the bladder at 48 or 72 hpi. However, the wild type outcompeted the locked-off mutant in the kidneys during the cochallenge experiment at 72 hpi (P = 0.009). Overall, these data suggest that the ability of the Invertible Element controlling type 1 fimbria expression to phase vary contributes significantly to virulence early (24 hpi) in the course of a urinary tract infection by UPEC and most profoundly influences colonization of the bladder.
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in vivo dynamics of type 1 fimbria regulation in uropathogenic escherichia coli during experimental urinary tract infection
Infection and Immunity, 2001Co-Authors: Nereus W Gunther, David E Johnson, Virginia C Lockatell, Harry L. T. MobleyAbstract:Escherichia coli is the primary cause of uncomplicated infections of the urinary tract including cystitis. More serious infections, characterized as acute pyelonephritis, can also develop. Type 1 fimbriae of E. coli contribute to virulence in the urinary tract; however, only recently has the expression of the type 1 fimbriae been investigated in vivo using molecular techniques. Transcription of type 1 fimbrial genes is controlled by a promoter that resides on a 314-bp Invertible Element capable of two orientations. One places the promoter in the ON orientation, allowing for transcription; the other places the promoter in the OFF orientation, preventing transcription. A PCR-based assay was developed to measure the orientation of the Invertible Element during an experimental urinary tract infection in mice. Using this assay, it was found that the percentage of the population ON in urine samples correlated with the respective CFU per gram of bladder (P = 0.0006) but not with CFU per gram of kidney (P > 0.069). Cystitis isolates present in the urine of mice during the course of infection had a higher percentage of their Invertible Elements in the ON orientation than did pyelonephritis isolates (85 and 34%, respectively, at 24 h; P < 0.0001). In general, cystitis isolates, unlike pyelonephritis isolates, were more likely to maintain their Invertible Elements in the ON orientation for the entire period of infection. E. coli cells expressing type 1 fimbriae, expelled in urine, were shown by scanning electron microscopy to be densely packed on the surface of uroepithelial cells. These results suggest that expression of type 1 fimbriae is more critical for cystitis strains than for pyelonephritis strains in the early stages of an infection during bladder colonization.
Virginia C Lockatell - One of the best experts on this subject based on the ideXlab platform.
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identification of mrpi as the sole recombinase that regulates the phase variation of mr p fimbria a bladder colonization factor of uropathogenic proteus mirabilis
Molecular Microbiology, 2002Co-Authors: Xin Li, David E Johnson, Virginia C Lockatell, Harry L. T. MobleyAbstract:Summary Proteus mirabilis is a common cause of urinary tract infection (UTI) in individuals with structural abnormalities or long-term catheterization. The expression of mannose-resistant/ Proteus -like (MR/P) fimbria is phase variable because of the inversion of a 251 bp DNA fragment that carries the promoter for the mrp operon. Previous studies have shown that mrpI , which is transcribed divergently from the mrp operon, encodes a recombinase capable of switching the orientation of this Invertible Element. In this study, we constructed isogenic mrpI null mutants from a clinical isolate of P. mirabilis , HI4320. A polymerase chain reaction (PCR)-based Invertible Element assay revealed that the isogenic mrpI null mutants were locked in one phase, either expressing (locked on) MR/P fimbriae or not (locked off), which indicated that MrpI was the sole recombinase that regulated the phase variation of MR/P fimbria. The locked-on and locked-off mutants were evaluated for virulence in the CBA mouse model of ascending UTI by co-challenges with each other and with the wild-type strain. Results from these experiments demonstrated conclusively that the MR/P fimbria was a critical bladder colonization factor of uropathogenic P. mirabilis and also suggested that the ability to switch off the expression of MR/P fimbria might be important for kidney colonization.
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assessment of virulence of uropathogenic escherichia coli type 1 fimbrial mutants in which the Invertible Element is phase locked on or off
Infection and Immunity, 2002Co-Authors: Nereus W Gunther, David E Johnson, Virginia C Lockatell, Jennifer A Snyder, Ian C Blomfield, Harry L. T. MobleyAbstract:Type 1 fimbria is a proven virulence factor of uropathogenic Escherichia coli (UPEC), causing urinary tract infections. Expression of the fimbria is regulated at the transcriptional level by a promoter situated on an Invertible Element, which can exist in one of two different orientations. The orientation of the Invertible Element that allows the expression of type 1 fimbriae is defined as “on,” and the opposite orientation, in which no transcription occurs, is defined as “off.” During the course of a urinary tract infection, we have observed that the infecting E. coli population alternates between fimbriated and nonfimbriated states, with the fimbriated on orientation peaking at 24 h. We propose that the ability of the Invertible Element to switch orientations during infection is itself a virulence trait. To test this hypothesis, nucleotide sequence changes were introduced in the left inverted repeat of the Invertible Element of UPEC pyelonephritis strain CFT073 that locked the Invertible Elements permanently in either the on or the off orientation. The virulence of these mutants was assessed in the CBA mouse model of ascending urinary tract infection at 4, 24, 48, and 72 h postinoculation (hpi). We conducted independent challenges, in which bladders of mice were inoculated with either a single mutant or the wild type, and cochallenges, in which a mutant and the wild type were inoculated together to allow direct competition in the urinary tract. In both sets of experimental infections, the locked-off mutant was recovered from the urine, bladder, and kidneys in significantly lower numbers than the wild type at 24 hpi (P ≤ 0.05), demonstrating its attenuation. Conversely, the locked-on mutant was recovered in higher numbers than the wild type at 24 hpi (P ≤ 0.05), showing enhanced virulence of this mutant. No significant differences were seen between the mutants and wild type in the urine or the bladder at 48 or 72 hpi. However, the wild type outcompeted the locked-off mutant in the kidneys during the cochallenge experiment at 72 hpi (P = 0.009). Overall, these data suggest that the ability of the Invertible Element controlling type 1 fimbria expression to phase vary contributes significantly to virulence early (24 hpi) in the course of a urinary tract infection by UPEC and most profoundly influences colonization of the bladder.
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in vivo dynamics of type 1 fimbria regulation in uropathogenic escherichia coli during experimental urinary tract infection
Infection and Immunity, 2001Co-Authors: Nereus W Gunther, David E Johnson, Virginia C Lockatell, Harry L. T. MobleyAbstract:Escherichia coli is the primary cause of uncomplicated infections of the urinary tract including cystitis. More serious infections, characterized as acute pyelonephritis, can also develop. Type 1 fimbriae of E. coli contribute to virulence in the urinary tract; however, only recently has the expression of the type 1 fimbriae been investigated in vivo using molecular techniques. Transcription of type 1 fimbrial genes is controlled by a promoter that resides on a 314-bp Invertible Element capable of two orientations. One places the promoter in the ON orientation, allowing for transcription; the other places the promoter in the OFF orientation, preventing transcription. A PCR-based assay was developed to measure the orientation of the Invertible Element during an experimental urinary tract infection in mice. Using this assay, it was found that the percentage of the population ON in urine samples correlated with the respective CFU per gram of bladder (P = 0.0006) but not with CFU per gram of kidney (P > 0.069). Cystitis isolates present in the urine of mice during the course of infection had a higher percentage of their Invertible Elements in the ON orientation than did pyelonephritis isolates (85 and 34%, respectively, at 24 h; P < 0.0001). In general, cystitis isolates, unlike pyelonephritis isolates, were more likely to maintain their Invertible Elements in the ON orientation for the entire period of infection. E. coli cells expressing type 1 fimbriae, expelled in urine, were shown by scanning electron microscopy to be densely packed on the surface of uroepithelial cells. These results suggest that expression of type 1 fimbriae is more critical for cystitis strains than for pyelonephritis strains in the early stages of an infection during bladder colonization.
Rodney A Welch - One of the best experts on this subject based on the ideXlab platform.
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identification and characterization of a phase variable Element that regulates the autotransporter upae in uropathogenic escherichia coli
Mbio, 2018Co-Authors: Eric J Battaglioli, Kelvin G K Goh, Tensin S Atruksang, Kevin J Schwartz, Mark A Schembri, Rodney A WelchAbstract:ABSTRACT Uropathogenic Escherichia coli (UPEC) is the most common etiologic agent of uncomplicated urinary tract infection (UTI). An important mechanism of gene regulation in UPEC is phase variation that involves inversion of a promoter-containing DNA Element via enzymatic activity of tyrosine recombinases, resulting in biphasic, ON or OFF expression of target genes. The UPEC reference strain CFT073 has five tyrosine site-specific recombinases that function at two previously characterized promoter inversion systems, fimS and hyxS. Three of the five recombinases are located proximally to their cognate target Elements, which is typical of promoter inversion systems. The genes for the other two recombinases, IpuA and IpuB, are located distal from these sites. Here, we identified and characterized a third phase-variable Invertible Element in CFT073, ipuS, located proximal to ipuA and ipuB. The inversion of ipuS is catalyzed by four of the five CFT073 recombinases. Orientation of the Element drives transcription of a two-gene operon containing ipuR, a predicted LuxR-type regulator, and upaE, a predicted autotransporter. We show that the predicted autotransporter UpaE is surface located and facilitates biofilm formation as well as adhesion to extracellular matrix proteins in a K-12 recombinant background. Consistent with this phenotype, the ipuS ON condition in CFT073 results in defective swimming motility, increased adherence to human kidney epithelial cells, and a positive competitive kidney colonization advantage in experimental mouse UTIs. Overall, the identification of a third phase switch in UPEC that is regulated by a shared set of recombinases describes a complex phase-variable virulence network in UPEC. IMPORTANCE Uropathogenic Escherichia coli (UPEC) is the most common cause of urinary tract infection (UTI). ON versus OFF phase switching by inversion of small DNA Elements at two chromosome sites in UPEC regulates the expression of important virulence factors, including the type 1 fimbria adhesion organelle. In this report, we describe a third Invertible Element, ipuS, in the UPEC reference strain CFT073. The inversion of ipuS controls the phase-variable expression of upaE, an autotransporter gene that encodes a surface protein involved in adherence to extracellular matrix proteins and colonization of the kidneys in a murine model of UTI.
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identification and characterization of a phase variable Element that regulates the autotransporter upae in uropathogenic escherichia coli
bioRxiv, 2018Co-Authors: Rodney A Welch, Kelvin G K Goh, Tensin S Atruksang, Kevin J Schwartz, Mark A Schembri, Eric J BattaglioliAbstract:Uropathogenic Escherichia coli (UPEC) are the most common etiological agent of uncomplicated urinary tract infection (UTI). An important mechanism of gene regulation in UPEC is phase variation that involves inversion of a promoter-containing DNA Element via enzymatic activity of tyrosine recombinases, resulting in biphasic, ON or OFF expression of target genes. The UPEC reference strain CFT073 has five tyrosine site-specific recombinases that function at two previously characterized promoter inversion systems, fimS and hyxS. Three of the five recombinases are located proximally to their cognate target Elements, which is typical of promoter inversion systems. The genes for the other two recombinases, IpuA and IpuB are located distal from these sites. Here, we identified and characterized a third phase variable Invertible Element in CFT073, ipuS located proximal to ipuA and ipuB. The inversion of ipuS is catalyzed by four of the five CFT073 recombinases. Orientation of the Element drives transcription of a two-gene operon containing ipuR, a predicted LuxR-type regulator, and upaE, a predicted autotransporter. We show that the predicted autotransporter UpaE is surface-located and facilitates biofilm formation as well as adhesion to extracellular matrix proteins in a K-12 recombinant background. Consistent with this phenotype, the ipuS ON condition in CFT073 results in defective swimming motility, increased adherence to human kidney epithelial cells, and a positive competitive kidney colonization advantage in experimental mouse UTI infections. Overall, the identification of a third phase-switch in UPEC that is regulated by a shared set of recombinases describes a complex phase-variable virulence network in UPEC.
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Identification and Characterization of a Phase-Variable Element That Regulates the Autotransporter UpaE in Uropathogenic Escherichia coli
'American Society for Microbiology', 2018Co-Authors: Eric J Battaglioli, Kelvin G K Goh, Mark A Schembri, T. S. Atruktsang, K. Schwartz, Rodney A WelchAbstract:Uropathogenic Escherichia coli (UPEC) is the most common etiologic agent of uncomplicated urinary tract infection (UTI). An important mechanism of gene regulation in UPEC is phase variation that involves inversion of a promoter-containing DNA Element via enzymatic activity of tyrosine recombinases, resulting in biphasic, ON or OFF expression of target genes. The UPEC reference strain CFT073 has five tyrosine site-specific recombinases that function at two previously characterized promoter inversion systems, fimS and hyxS. Three of the five recombinases are located proximally to their cognate target Elements, which is typical of promoter inversion systems. The genes for the other two recombinases, IpuA and IpuB, are located distal from these sites. Here, we identified and characterized a third phase-variable Invertible Element in CFT073, ipuS, located proximal to ipuA and ipuB. The inversion of ipuS is catalyzed by four of the five CFT073 recombinases. Orientation of the Element drives transcription of a two-gene operon containing ipuR, a predicted LuxR-type regulator, and upaE, a predicted autotransporter. We show that the predicted autotransporter UpaE is surface located and facilitates biofilm formation as well as adhesion to extracellular matrix proteins in a K-12 recombinant background. Consistent with this phenotype, the ipuS ON condition in CFT073 results in defective swimming motility, increased adherence to human kidney epithelial cells, and a positive competitive kidney colonization advantage in experimental mouse UTIs. Overall, the identification of a third phase switch in UPEC that is regulated by a shared set of recombinases describes a complex phase-variable virulence network in UPEC.Uropathogenic Escherichia coli (UPEC) is the most common cause of urinary tract infection (UTI). ON versus OFF phase switching by inversion of small DNA Elements at two chromosome sites in UPEC regulates the expression of important virulence factors, including the type 1 fimbria adhesion organelle. In this report, we describe a third Invertible Element, ipuS, in the UPEC reference strain CFT073. The inversion of ipuS controls the phase-variable expression of upaE, an autotransporter gene that encodes a surface protein involved in adherence to extracellular matrix proteins and colonization of the kidneys in a murine model of UTI
