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David Beighton - One of the best experts on this subject based on the ideXlab platform.
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emended description of Actinomyces Naeslundii and descriptions of Actinomyces oris sp nov and Actinomyces johnsonii sp nov previously identified as Actinomyces Naeslundii genospecies 1 2 and wva 963
International Journal of Systematic and Evolutionary Microbiology, 2009Co-Authors: Uta Henssge, Thuy Do, S C Gilbert, D T Clark, David R. Radford, David BeightonAbstract:Actinomyces Naeslundii is an important early colonizer in the oral biofilm and consists of three genospecies (1, 2 and WVA 963) which cannot be readily differentiated using conventional phenotypic testing or on the basis of 16S rRNA gene sequencing. We have investigated a representative collection of type and reference strains and clinical and oral isolates (n=115) and determined the partial gene sequences of six housekeeping genes (atpA, rpoB, pgi, metG, gltA and gyrA). These sequences identified the three genospecies and differentiated them from Actinomyces viscosus isolated from rodents. The partial sequences of atpA and metG gave best separation of the three genospecies. A. Naeslundii genospecies 1 and 2 formed two distinct clusters, well separated from both genospecies WVA 963 and A. viscosus. Analysis of the same genes in other oral Actinomyces species (Actinomyces gerencseriae, A. israelii, A. meyeri, A. odontolyticus and A. georgiae) indicated that, when sequence data were obtained, these species each exhibited <90 % similarity with the A. Naeslundii genospecies. Based on these data, we propose the name Actinomyces oris sp. nov. (type strain ATCC 27044T =CCUG 34288T) for A. Naeslundii genospecies 2 and Actinomyces johnsonii sp. nov. (type strain ATCC 49338T =CCUG 34287T) for A. Naeslundii genospecies WVA 963. A. Naeslundii genospecies 1 should remain as A. Naeslundii sensu stricto, with the type strain ATCC 12104T =NCTC 10301T =CCUG 2238T.
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Emended description of Actinomyces Naeslundii and descriptions of Actinomyces oris sp. nov. and Actinomyces johnsonii sp. nov., previously identified as Actinomyces Naeslundii genospecies 1, 2 and WVA 963
International Journal of Systematic and Evolutionary Microbiology, 2009Co-Authors: Uta Henssge, Thuy Do, S C Gilbert, D T Clark, David R. Radford, David BeightonAbstract:Actinomyces Naeslundii is an important early colonizer in the oral biofilm and consists of three genospecies (1, 2 and WVA 963) which cannot be readily differentiated using conventional phenotypic testing or on the basis of 16S rRNA gene sequencing. We have investigated a representative collection of type and reference strains and clinical and oral isolates (n=115) and determined the partial gene sequences of six housekeeping genes (atpA, rpoB, pgi, metG, gltA and gyrA). These sequences identified the three genospecies and differentiated them from Actinomyces viscosus isolated from rodents. The partial sequences of atpA and metG gave best separation of the three genospecies. A. Naeslundii genospecies 1 and 2 formed two distinct clusters, well separated from both genospecies WVA 963 and A. viscosus. Analysis of the same genes in other oral Actinomyces species (Actinomyces gerencseriae, A. israelii, A. meyeri, A. odontolyticus and A. georgiae) indicated that, when sequence data were obtained, these species each exhibited
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evidence for recombination between a sialidase nanh of Actinomyces Naeslundii and Actinomyces oris previously named Actinomyces Naeslundii genospecies 1 and 2
Fems Microbiology Letters, 2008Co-Authors: Uta Henssge, S C Gilbert, D T Clark, David BeightonAbstract:Actinomyces spp., predominant members of human oral biofilms, may use extracellular sialidase to promote adhesion, deglycosylate immunoglobulins and liberation of nutrients. Partial nanH gene sequences (1,077 bp) from Actinomyces oris (n=74), Actinomyces Naeslundii (n=30), Actinomyces viscosus (n=1) and Actinomyces johnsonii (n=2) which included the active-site region and the bacterial neuraminidase repeats (BNRs) were compared. The sequences were aligned and each species formed a distinct cluster with five isolates having intermediate positions. These five isolates (two A. oris and three A. Naeslundii) exhibited interspecies recombination. The nonsynonymous/synonymous ratio was <1 for both A. oris and A. Naeslundii indicating that nanH in both species is under stabilizing selective pressure; nonsynonymous mutations are not selected. However, for A. oris significant negative values in tests for neutral selection suggested the rate of mutation in A. oris was greater than in A. Naeslundii but with selection against nonsynonymous mutations. This was supported by the observation that the frequency of polymorphic sites in A. oris, which were monomorphic in A. Naeslundii was significantly greater than the frequency of polymorphic sites in A. Naeslundii which were monomorphic in A. oris (chi(2)=7.011; P=0.00081). The higher proportions of A. oris in the oral biofilm might be explained by the higher mutation rate facilitating an increased ability to respond successfully to environmental stress.
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Evidence for recombination between a sialidase (nanH) of Actinomyces Naeslundii and Actinomyces oris, previously named 'Actinomyces Naeslundii genospecies 1 and 2'.
Fems Microbiology Letters, 2008Co-Authors: Thuy Do, Uta Henssge, S C Gilbert, D T Clark, David BeightonAbstract:Actinomyces spp., predominant members of human oral biofilms, may use extracellular sialidase to promote adhesion, deglycosylate immunoglobulins and liberation of nutrients. Partial nanH gene sequences (1077 bp) from Actinomyces oris (n =74), Actinomyces Naeslundii (n =30), Actinomyces viscosus (n =1) and Actinomyces johnsonii (n =2) which included the active-site region and the bacterial neuraminidase repeats (BNRs) were compared. The sequences were aligned and each species formed a distinct cluster with five isolates having intermediate positions. These five isolates (two A. oris and three A. Naeslundii) exhibited interspecies recombination. The nonsynonymous/synonymous ratio was
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Effect of Biofilm Growth on Expression of Surface Proteins of Actinomyces Naeslundii Genospecies 2
Applied and Environmental Microbiology, 2006Co-Authors: James S. Paddick, David Beighton, Susan Brailsford, Susmitha Rao, Renata F. Soares, Edwina A. M. Kidd, Karen A. HomerAbstract:The predominant surface proteins of biofilm and planktonic Actinomyces Naeslundii, a primary colonizer of the tooth surface, were examined. Seventy-nine proteins (the products of 52 genes) were identified in biofilm cells, and 30 of these, including adhesins, chaperones, and stress-response proteins, were significantly up-regulated relative to planktonic cells.
Uta Henssge - One of the best experts on this subject based on the ideXlab platform.
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emended description of Actinomyces Naeslundii and descriptions of Actinomyces oris sp nov and Actinomyces johnsonii sp nov previously identified as Actinomyces Naeslundii genospecies 1 2 and wva 963
International Journal of Systematic and Evolutionary Microbiology, 2009Co-Authors: Uta Henssge, Thuy Do, S C Gilbert, D T Clark, David R. Radford, David BeightonAbstract:Actinomyces Naeslundii is an important early colonizer in the oral biofilm and consists of three genospecies (1, 2 and WVA 963) which cannot be readily differentiated using conventional phenotypic testing or on the basis of 16S rRNA gene sequencing. We have investigated a representative collection of type and reference strains and clinical and oral isolates (n=115) and determined the partial gene sequences of six housekeeping genes (atpA, rpoB, pgi, metG, gltA and gyrA). These sequences identified the three genospecies and differentiated them from Actinomyces viscosus isolated from rodents. The partial sequences of atpA and metG gave best separation of the three genospecies. A. Naeslundii genospecies 1 and 2 formed two distinct clusters, well separated from both genospecies WVA 963 and A. viscosus. Analysis of the same genes in other oral Actinomyces species (Actinomyces gerencseriae, A. israelii, A. meyeri, A. odontolyticus and A. georgiae) indicated that, when sequence data were obtained, these species each exhibited <90 % similarity with the A. Naeslundii genospecies. Based on these data, we propose the name Actinomyces oris sp. nov. (type strain ATCC 27044T =CCUG 34288T) for A. Naeslundii genospecies 2 and Actinomyces johnsonii sp. nov. (type strain ATCC 49338T =CCUG 34287T) for A. Naeslundii genospecies WVA 963. A. Naeslundii genospecies 1 should remain as A. Naeslundii sensu stricto, with the type strain ATCC 12104T =NCTC 10301T =CCUG 2238T.
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Emended description of Actinomyces Naeslundii and descriptions of Actinomyces oris sp. nov. and Actinomyces johnsonii sp. nov., previously identified as Actinomyces Naeslundii genospecies 1, 2 and WVA 963
International Journal of Systematic and Evolutionary Microbiology, 2009Co-Authors: Uta Henssge, Thuy Do, S C Gilbert, D T Clark, David R. Radford, David BeightonAbstract:Actinomyces Naeslundii is an important early colonizer in the oral biofilm and consists of three genospecies (1, 2 and WVA 963) which cannot be readily differentiated using conventional phenotypic testing or on the basis of 16S rRNA gene sequencing. We have investigated a representative collection of type and reference strains and clinical and oral isolates (n=115) and determined the partial gene sequences of six housekeeping genes (atpA, rpoB, pgi, metG, gltA and gyrA). These sequences identified the three genospecies and differentiated them from Actinomyces viscosus isolated from rodents. The partial sequences of atpA and metG gave best separation of the three genospecies. A. Naeslundii genospecies 1 and 2 formed two distinct clusters, well separated from both genospecies WVA 963 and A. viscosus. Analysis of the same genes in other oral Actinomyces species (Actinomyces gerencseriae, A. israelii, A. meyeri, A. odontolyticus and A. georgiae) indicated that, when sequence data were obtained, these species each exhibited
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evidence for recombination between a sialidase nanh of Actinomyces Naeslundii and Actinomyces oris previously named Actinomyces Naeslundii genospecies 1 and 2
Fems Microbiology Letters, 2008Co-Authors: Uta Henssge, S C Gilbert, D T Clark, David BeightonAbstract:Actinomyces spp., predominant members of human oral biofilms, may use extracellular sialidase to promote adhesion, deglycosylate immunoglobulins and liberation of nutrients. Partial nanH gene sequences (1,077 bp) from Actinomyces oris (n=74), Actinomyces Naeslundii (n=30), Actinomyces viscosus (n=1) and Actinomyces johnsonii (n=2) which included the active-site region and the bacterial neuraminidase repeats (BNRs) were compared. The sequences were aligned and each species formed a distinct cluster with five isolates having intermediate positions. These five isolates (two A. oris and three A. Naeslundii) exhibited interspecies recombination. The nonsynonymous/synonymous ratio was <1 for both A. oris and A. Naeslundii indicating that nanH in both species is under stabilizing selective pressure; nonsynonymous mutations are not selected. However, for A. oris significant negative values in tests for neutral selection suggested the rate of mutation in A. oris was greater than in A. Naeslundii but with selection against nonsynonymous mutations. This was supported by the observation that the frequency of polymorphic sites in A. oris, which were monomorphic in A. Naeslundii was significantly greater than the frequency of polymorphic sites in A. Naeslundii which were monomorphic in A. oris (chi(2)=7.011; P=0.00081). The higher proportions of A. oris in the oral biofilm might be explained by the higher mutation rate facilitating an increased ability to respond successfully to environmental stress.
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Evidence for recombination between a sialidase (nanH) of Actinomyces Naeslundii and Actinomyces oris, previously named 'Actinomyces Naeslundii genospecies 1 and 2'.
Fems Microbiology Letters, 2008Co-Authors: Thuy Do, Uta Henssge, S C Gilbert, D T Clark, David BeightonAbstract:Actinomyces spp., predominant members of human oral biofilms, may use extracellular sialidase to promote adhesion, deglycosylate immunoglobulins and liberation of nutrients. Partial nanH gene sequences (1077 bp) from Actinomyces oris (n =74), Actinomyces Naeslundii (n =30), Actinomyces viscosus (n =1) and Actinomyces johnsonii (n =2) which included the active-site region and the bacterial neuraminidase repeats (BNRs) were compared. The sequences were aligned and each species formed a distinct cluster with five isolates having intermediate positions. These five isolates (two A. oris and three A. Naeslundii) exhibited interspecies recombination. The nonsynonymous/synonymous ratio was
P A Ragsdale - One of the best experts on this subject based on the ideXlab platform.
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identification of a gene involved in assembly of Actinomyces Naeslundii t14v type 2 fimbriae
Infection and Immunity, 1998Co-Authors: Maria K Yeung, Jacob A Donkersloot, John O Cisar, P A RagsdaleAbstract:The nucleotide sequence of the Actinomyces Naeslundii T14V type 2 fimbrial structural subunit gene, fimA, and the 3' flanking DNA region was determined. The fimA gene encoded a 535-amino-acid precursor subunit protein (FimA) which included both N-terminal leader and C-terminal cell wall sorting sequences. A second gene, designated orf365, that encoded a 365-amino-acid protein which contained a putative transmembrane segment was identified immediately 3' to fimA. Mutants in which either fimA or orf365 was replaced with a kanamycin resistance gene did not participate in type 2 fimbriae-mediated coaggregation with Streptococcus oralis 34. Type 2 fimbrial antigen was not detected in cell extracts of the fimA mutant by Western blotting with anti-A. Naeslundii type 2 fimbrial antibody, but the subunit protein was detected in extracts of the orf365 mutant. The subunit protein detected in this mutant also was immunostained by an antibody raised against a synthetic peptide representing the C-terminal 20 amino acid residues of the predicted FimA. The antipeptide antibody reacted with FimA isolated from the recombinant Escherichia coli clone containing fimA but did not react with purified type 2 fimbriae in extracts of the wild-type strain. These results indicate that synthesis of type 2 fimbriae in A. Naeslundii T14V may involve posttranslational cleavage of both the N-terminal and C-terminal peptides of the precursor subunit and also the expression of orf365.
John O Cisar - One of the best experts on this subject based on the ideXlab platform.
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Amended Description of the Genes for Synthesis of Actinomyces Naeslundii T14V Type 1 Fimbriae and Associated Adhesin
Infection and Immunity, 2007Co-Authors: Ping Chen, John O Cisar, Sonja Hess, Kai P. LeungAbstract:The type 1 fimbriae of Actinomyces Naeslundii T14V mediate adhesion of this gram-positive species to the tooth surface. The present findings show that the locus for type 1 fimbria production in this strain includes three genes, fimQ for a minor fimbrial subunit that appears to be an adhesin, fimP for the major structural subunit, and srtC1 for a type 1 fimbria-specific sortase involved in the assembly of these structures.
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sortase catalyzed assembly of distinct heteromeric fimbriae in Actinomyces Naeslundii
Journal of Bacteriology, 2007Co-Authors: Arunima Mishra, John O Cisar, Hung TonthatAbstract:Two types of adhesive fimbriae are expressed by Actinomyces; however, the architecture and the mechanism of assembly of these structures remain poorly understood. In this study we characterized two fimbrial gene clusters present in the genome of Actinomyces Naeslundii strain MG-1. By using immunoelectron microscopy and biochemical analysis, we showed that the fimQ-fimP-srtC1-fimR gene cluster encodes a fimbrial structure (designated type 1) that contains a major subunit, FimP, forming the shaft and a minor subunit, FimQ, located primarily at the tip. Similarly, the fimB-fimA-srtC2 gene cluster encodes a distinct fimbrial structure (designated type 2) composed of a shaft protein, FimA, and a tip protein, FimB. By using allelic exchange, we constructed an in-frame deletion mutant that lacks the SrtC2 sortase. This mutant produces abundant type 1 fimbriae and expresses the monomeric FimA and FimB proteins, but it does not assemble type 2 fimbriae. Thus, SrtC2 is a fimbria-specific sortase that is essential for assembly of the type 2 fimbriae. Together, our experiments pave the way for several lines of molecular investigation that are necessary to elucidate the fimbrial assembly pathways in Actinomyces and their function in the pathogenesis of different biofilm-related oral diseases.
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identification of a gene involved in assembly of Actinomyces Naeslundii t14v type 2 fimbriae
Infection and Immunity, 1998Co-Authors: Maria K Yeung, Jacob A Donkersloot, John O Cisar, P A RagsdaleAbstract:The nucleotide sequence of the Actinomyces Naeslundii T14V type 2 fimbrial structural subunit gene, fimA, and the 3' flanking DNA region was determined. The fimA gene encoded a 535-amino-acid precursor subunit protein (FimA) which included both N-terminal leader and C-terminal cell wall sorting sequences. A second gene, designated orf365, that encoded a 365-amino-acid protein which contained a putative transmembrane segment was identified immediately 3' to fimA. Mutants in which either fimA or orf365 was replaced with a kanamycin resistance gene did not participate in type 2 fimbriae-mediated coaggregation with Streptococcus oralis 34. Type 2 fimbrial antigen was not detected in cell extracts of the fimA mutant by Western blotting with anti-A. Naeslundii type 2 fimbrial antibody, but the subunit protein was detected in extracts of the orf365 mutant. The subunit protein detected in this mutant also was immunostained by an antibody raised against a synthetic peptide representing the C-terminal 20 amino acid residues of the predicted FimA. The antipeptide antibody reacted with FimA isolated from the recombinant Escherichia coli clone containing fimA but did not react with purified type 2 fimbriae in extracts of the wild-type strain. These results indicate that synthesis of type 2 fimbriae in A. Naeslundii T14V may involve posttranslational cleavage of both the N-terminal and C-terminal peptides of the precursor subunit and also the expression of orf365.
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Fimbrial-mediated colonization of murine teeth by Actinomyces Naeslundii.
Oral Microbiology and Immunology, 1996Co-Authors: J E Beem, John O Cisar, C. G. Hurley, W. E. Nesbitt, D.f. Croft, R. G. Marks, W. B. ClarkAbstract:Groups of mice fed diets high in sucrose or glucose were orally inoculated with 10(10), 10(9) or 10(8) colony-forming units of one of the following Actinomyces Naeslundii strains possessing the type 1 (T1+) and/or the type 2 (T2+) fimbriae: T14VJ1 (T1+, T2+), 5519 (T1+), 5951 (T2+), and 147 (non-fimbriated). Ninety-six hours after inoculation their upper jaws were cultured to look at the implantation of each of these strains on the teeth. In mice fed a sucrose diet, regardless of the presence or absence of fimbriae, each bacterial strain colonized 100% of the mice at the highest inoculation doses of the infecting organism. But at a dose of 10(8), T14V-J1 was the only strain which colonized 100% (12/12) of the mice, 5519 colonized 10/11, 5951 colonized 9/11 and 147 colonized 7/11. These differences were not statistically significant. When mice were fed a high-glucose diet, 100% infection was achieved with strains T14V-J1, 5519 and 5951 only at the highest dose of 10(10) colony-forming units. Strain 147 colonized in 8/9 of the mice at that dosage. At lower dosages, no bacterial strain implanted in 100% of the mice. In the glucose experiment at a dose of 10(8), strains expressing the T1 fimbriae implanted significantly better than strains without the T1 fimbriae. At a dose of 10(9) colony-forming units, the parent strain T14V-J1 implanted significantly better than strains without the T1 fimbriae. Similarly, strain 5519 (T1+) implanted significantly better than 5951 and implanted better than 147, although the difference was not significant. These results suggest that while the presence of the T1 and T2 fimbriae may confer some advantage in the establishment of these organisms in vivo, even the strains without fimbriae were able to colonize. Strains T14VJ1 and 5519 were found to bind well to hydroxyapatite treated with mouse saliva, while strains 5951 and 147 did not. Only T2 fimbriated strains T14V-J1 and 5951 exhibited a lactose-reversible coaggreation with indigenous strains of enterococci that may contribute to the elevated levels of colonization of strain 5951 in vivo.
D T Clark - One of the best experts on this subject based on the ideXlab platform.
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emended description of Actinomyces Naeslundii and descriptions of Actinomyces oris sp nov and Actinomyces johnsonii sp nov previously identified as Actinomyces Naeslundii genospecies 1 2 and wva 963
International Journal of Systematic and Evolutionary Microbiology, 2009Co-Authors: Uta Henssge, Thuy Do, S C Gilbert, D T Clark, David R. Radford, David BeightonAbstract:Actinomyces Naeslundii is an important early colonizer in the oral biofilm and consists of three genospecies (1, 2 and WVA 963) which cannot be readily differentiated using conventional phenotypic testing or on the basis of 16S rRNA gene sequencing. We have investigated a representative collection of type and reference strains and clinical and oral isolates (n=115) and determined the partial gene sequences of six housekeeping genes (atpA, rpoB, pgi, metG, gltA and gyrA). These sequences identified the three genospecies and differentiated them from Actinomyces viscosus isolated from rodents. The partial sequences of atpA and metG gave best separation of the three genospecies. A. Naeslundii genospecies 1 and 2 formed two distinct clusters, well separated from both genospecies WVA 963 and A. viscosus. Analysis of the same genes in other oral Actinomyces species (Actinomyces gerencseriae, A. israelii, A. meyeri, A. odontolyticus and A. georgiae) indicated that, when sequence data were obtained, these species each exhibited <90 % similarity with the A. Naeslundii genospecies. Based on these data, we propose the name Actinomyces oris sp. nov. (type strain ATCC 27044T =CCUG 34288T) for A. Naeslundii genospecies 2 and Actinomyces johnsonii sp. nov. (type strain ATCC 49338T =CCUG 34287T) for A. Naeslundii genospecies WVA 963. A. Naeslundii genospecies 1 should remain as A. Naeslundii sensu stricto, with the type strain ATCC 12104T =NCTC 10301T =CCUG 2238T.
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Emended description of Actinomyces Naeslundii and descriptions of Actinomyces oris sp. nov. and Actinomyces johnsonii sp. nov., previously identified as Actinomyces Naeslundii genospecies 1, 2 and WVA 963
International Journal of Systematic and Evolutionary Microbiology, 2009Co-Authors: Uta Henssge, Thuy Do, S C Gilbert, D T Clark, David R. Radford, David BeightonAbstract:Actinomyces Naeslundii is an important early colonizer in the oral biofilm and consists of three genospecies (1, 2 and WVA 963) which cannot be readily differentiated using conventional phenotypic testing or on the basis of 16S rRNA gene sequencing. We have investigated a representative collection of type and reference strains and clinical and oral isolates (n=115) and determined the partial gene sequences of six housekeeping genes (atpA, rpoB, pgi, metG, gltA and gyrA). These sequences identified the three genospecies and differentiated them from Actinomyces viscosus isolated from rodents. The partial sequences of atpA and metG gave best separation of the three genospecies. A. Naeslundii genospecies 1 and 2 formed two distinct clusters, well separated from both genospecies WVA 963 and A. viscosus. Analysis of the same genes in other oral Actinomyces species (Actinomyces gerencseriae, A. israelii, A. meyeri, A. odontolyticus and A. georgiae) indicated that, when sequence data were obtained, these species each exhibited
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evidence for recombination between a sialidase nanh of Actinomyces Naeslundii and Actinomyces oris previously named Actinomyces Naeslundii genospecies 1 and 2
Fems Microbiology Letters, 2008Co-Authors: Uta Henssge, S C Gilbert, D T Clark, David BeightonAbstract:Actinomyces spp., predominant members of human oral biofilms, may use extracellular sialidase to promote adhesion, deglycosylate immunoglobulins and liberation of nutrients. Partial nanH gene sequences (1,077 bp) from Actinomyces oris (n=74), Actinomyces Naeslundii (n=30), Actinomyces viscosus (n=1) and Actinomyces johnsonii (n=2) which included the active-site region and the bacterial neuraminidase repeats (BNRs) were compared. The sequences were aligned and each species formed a distinct cluster with five isolates having intermediate positions. These five isolates (two A. oris and three A. Naeslundii) exhibited interspecies recombination. The nonsynonymous/synonymous ratio was <1 for both A. oris and A. Naeslundii indicating that nanH in both species is under stabilizing selective pressure; nonsynonymous mutations are not selected. However, for A. oris significant negative values in tests for neutral selection suggested the rate of mutation in A. oris was greater than in A. Naeslundii but with selection against nonsynonymous mutations. This was supported by the observation that the frequency of polymorphic sites in A. oris, which were monomorphic in A. Naeslundii was significantly greater than the frequency of polymorphic sites in A. Naeslundii which were monomorphic in A. oris (chi(2)=7.011; P=0.00081). The higher proportions of A. oris in the oral biofilm might be explained by the higher mutation rate facilitating an increased ability to respond successfully to environmental stress.
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Evidence for recombination between a sialidase (nanH) of Actinomyces Naeslundii and Actinomyces oris, previously named 'Actinomyces Naeslundii genospecies 1 and 2'.
Fems Microbiology Letters, 2008Co-Authors: Thuy Do, Uta Henssge, S C Gilbert, D T Clark, David BeightonAbstract:Actinomyces spp., predominant members of human oral biofilms, may use extracellular sialidase to promote adhesion, deglycosylate immunoglobulins and liberation of nutrients. Partial nanH gene sequences (1077 bp) from Actinomyces oris (n =74), Actinomyces Naeslundii (n =30), Actinomyces viscosus (n =1) and Actinomyces johnsonii (n =2) which included the active-site region and the bacterial neuraminidase repeats (BNRs) were compared. The sequences were aligned and each species formed a distinct cluster with five isolates having intermediate positions. These five isolates (two A. oris and three A. Naeslundii) exhibited interspecies recombination. The nonsynonymous/synonymous ratio was