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Ry Young - One of the best experts on this subject based on the ideXlab platform.
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Genetic Dissection of T4 Lysis
Journal of bacteriology, 2014Co-Authors: Samir H. Moussa, Jessica L. Lawler, Ry YoungAbstract:ABSTRACT t is the Holin gene for coliphage T4, encoding a 218-amino-acid (aa) protein essential for the inner membrane hole formation that initiates lysis and terminates the phage infection cycle. T is predicted to be an integral membrane protein that adopts an N in -C out topology with a single transmembrane domain (TMD). This Holin topology is different from those of the well-studied Holins S105 (3 TMDs; N out -C in ) of the coliphage lambda and S68 (2 TMDs; N in -C in ) of the lambdoid phage 21. Here, we used random mutagenesis to construct a library of lysis-defective alleles of t to discern residues and domains important for Holin function and for the inhibition of lysis by the T4 antiHolin, RI. The results show that mutations in all 3 topological domains (N-terminal cytoplasmic, TMD, and C-terminal periplasmic) can abrogate Holin function. Additionally, several lysis-defective alleles in the C-terminal domain are no longer competent in binding RI. Taken together, these results shed light on the roles of the previously uncharacterized N-terminal and C-terminal domains in lysis and its real-time regulation.
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Stable micron-scale holes are a general feature of canonical Holins.
Molecular microbiology, 2013Co-Authors: Christos G Savva, Samir H. Moussa, Jill S. Dewey, Andreas Holzenburg, Ry YoungAbstract:Summary At a programmed time in phage infection cycles, canonical Holins suddenly trigger to cause lethal damage to the cytoplasmic membrane, resulting in the cessation of respiration and the non-specific release of pre-folded, fully active endolysins to the periplasm. For the paradigm Holin S105 of lambda, triggering is correlated with the formation of micron-scale membrane holes, visible as interruptions in the bilayer in cryo-electron microscopic images and tomographic reconstructions. Here we report that the size distribution of the holes is stable for long periods after triggering. Moreover, early triggering caused by an early lysis allele of S105 formed approximately the same number of holes, but the lesions were significantly smaller. In contrast, early triggering prematurely induced by energy poisons resulted in many fewer visible holes, consistent with previous sizing studies. Importantly, the unrelated canonical Holins P2 Y and T4 T were found to cause the formation of holes of approximately the same size and number as for lambda. In contrast, no such lesions were visible after triggering of the pinHolin S2168. These results generalize the hole formation phenomenon for canonical Holins. A model is presented suggesting the unprecedentedly large size of these holes is related to the timing mechanism.
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Functional Analysis of a Class I Holin, P2 Y
Journal of bacteriology, 2013Co-Authors: Jill S. Dewey, Taehyun Park, Jeremy Weaver, Ry YoungAbstract:Y is the putative Holin gene of the paradigm coliphage P2 and encodes a 93-amino-acid protein. Y is predicted to be an integral membrane protein that adopts an N-out C-in membrane topology with 3 transmembrane domains (TMDs) and a highly charged C-terminal cytoplasmic tail. The same features are observed in the canonical class I lambda Holin, the S105 protein of phage lambda, which controls lysis by forming holes in the plasma membrane at a programmed time. S105 has been the subject of intensive genetic, cellular, and biochemical analyses. Although Y is not related to S105 in its primary structure, its characterization might prove useful in discerning the essential traits for Holin function. Here, we used physiological and genetic approaches to show that Y exhibits the essential Holin functional criteria, namely, allele-specific delayed-onset lethality and sensitivity to the energization of the membrane. Taken together, these results suggest that class I Holins share a set of unusual features that are needed for their remarkable ability to program the end of the phage infection cycle with precise timing. However, Y Holin function requires the integrity of its short cytoplasmic C-terminal domain, unlike for S105. Finally, instead of encoding a second translational product of Y as an antiHolin, as shown for lambda S107, the P2 lysis cassette encodes another predicted membrane protein, LysA, which is shown here to have a Y-specific antiHolin character.
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Active Bax and Bak are functional Holins
Genes & development, 2011Co-Authors: Xiaming Pang, Samir H. Moussa, Kenneth W. Bayles, Natalie M. Targy, Jeffrey L. Bose, Nicholas M. George, Casey M. Gries, Hernando Lopez, Liqiang Zhang, Ry YoungAbstract:The mechanism of Bax/Bak-dependent mitochondrial outer membrane permeabilization (MOMP), a central apoptotic event primarily controlled by the Bcl-2 family proteins, remains not well understood. Here, we express active Bax/Bak in bacteria, the putative origin of mitochondria, and examine their functional similarities to the λ bacteriophage (λ) Holin. As critical effectors for bacterial lysis, Holin oligomers form membrane lesions, through which endolysin, a muralytic enzyme, escapes the cytoplasm to attack the cell wall at the end of the infection cycle. We found that active Bax/Bak, but not any other Bcl-2 family protein, displays Holin behavior, causing bacterial lysis by releasing endolysin in an oligomerization-dependent manner. Strikingly, replacing the Holin gene with active alleles of Bax/Bak results in plaque-forming phages. Furthermore, we provide evidence that active Bax produces large membrane holes, the size of which is controlled by structural elements of Bax. Notably, lysis by active Bax is inhibited by Bcl-xL, and the lysis activity of the wild-type Bax is stimulated by a BH3-only protein. Together, these results mechanistically link MOMP to Holin-mediated hole formation in the bacterial plasma membrane.
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Holin triggering in real time
Proceedings of the National Academy of Sciences of the United States of America, 2010Co-Authors: Rebecca L. White, Ting Pang, Christos G Savva, Jill S. Dewey, Andreas Holzenburg, Shinobu Chiba, Kit Pogliano, Ry YoungAbstract:During λ infections, the Holin S105 accumulates harmlessly in the membrane until, at an allele-specific time, suddenly triggering to form irregular holes of unprecedented size (>300 nm), releasing the endolysin from the cytoplasm, resulting in lysis within seconds. Here we used a functional S105–GFP chimera and real-time deconvolution fluorescence microscopy to show that the S105–GFP fusion accumulated in a uniformly distributed fashion, until suddenly, within 1 min, it formed aggregates, or rafts, at the time of lethal triggering. Moreover, the isogenic fusion to a nonlethal S105 mutant remained uniformly distributed, whereas a fusion to an early-lysing mutant showed early triggering and early raft formation. Protein accumulation rates of the WT, early, and nonlethal alleles were identical. Fluorescence recovery after photobleaching (FRAP) revealed that the nonlethal mutant and untriggered WT hybrids were highly mobile in the membrane, whereas the WT raft was essentially immobile. Finally, an antiHolin allele, S105ΔTMD1–mcherryfp, in the product of which the S105 sequence deleted for the first transmembrane domain was fused to mCherryFP. This hybrid retained full antiHolin activity, in that it blocked lethal hole formation by the S105–GFP fusion, accumulated uniformly throughout the host membrane and prevented the S105–GFP protein from forming rafts. These findings suggest that phage lysis occurs when the Holin reaches a critical concentration and nucleates to form rafts, analogous to the initiation of purple membrane formation after the induction of bacteriorhodopsin in halobacteria. This model for Holin function may be relevant for processes in mammalian cells, including the release of nonenveloped viruses and apoptosis.
Udo Bläsi - One of the best experts on this subject based on the ideXlab platform.
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Bacteriophage-encoded toxins: the lambda-Holin protein causes caspase-independent non-apoptotic cell death of eukaryotic cells
Cellular microbiology, 2007Co-Authors: Chukwuma A. Agu, Udo Bläsi, Reinhard Klein, Brian Salmons, Walter H. Günzburg, Johannes Lengler, Franz Schilcher, Wolfgang Gregor, Thomas Peterbauer, Christine HohenadlAbstract:The bacteriophage-encoded Holin proteins are known to promote bacterial cell lysis by forming lesions within the cytoplasmic membrane. Recently, we have shown that the bacteriophage lambda-Holin protein exerts cytotoxic activity also in eukaryotic cells accounting for a reduced tumour growth in vivo. In order to elucidate the mechanisms of lambda-Holin-induced mammalian cell death, detailed biochemical and morphological analyses were performed. Colocalization analyses by subcellular fractionation and organelle-specific fluorescence immunocytochemistry indicated the presence of the lambda-Holin protein in the endoplasmic reticulum and in mitochondria. Functional studies using the mitochondria-specific fluorochrome JC-1 demonstrated a loss of mitochondrial transmembrane potential in response to lambda-Holin expression. Morphologically, these cells exhibited unfragmented nuclei but severe cytoplasmic vacuolization representing signs of oncosis/necrosis rather than apoptosis. Consistently, Western blot analyses indicated neither an activation of effector caspases 3 and 7 nor cleavage of the respective substrate poly(ADP-ribose) polymerase (PARP) in an apoptosis-specific manner. These findings suggest that the lambda-Holin protein mediates a caspase-independent non-apoptotic mode of cell death.
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the cytotoxic activity of the bacteriophage λ Holin protein reduces tumour growth rates in mammary cancer cell xenograft models
Journal of Gene Medicine, 2006Co-Authors: Chukwuma A. Agu, Udo Bläsi, Reinhard Klein, Sonja Schwab, Petra Kodajova, Michael Ausserlechner, Bernhard Binishofer, Brian Salmons, Marielle Konigschuster, Walter H. GünzburgAbstract:Background The potential use of gene therapy for cancer treatment is being intensively studied. One approach utilises the expression of genes encoding cytotoxic proteins. Such proteins can affect cellular viability, for example by inhibiting the translation machinery or disturbing membrane integrity. The bacteriophage Lambda (λ)-Holin protein is known to form a lesion in the cytoplasmic membrane of E. coli, triggering bacterial cell lysis and thereby enabling the release of new bacteriophage particles. The aim of this study was to evaluate whether the λ-Holin protein has a cytotoxic impact on eukaryotic cells and whether it holds potential as a new therapeutic protein for cancer gene therapy. Methods To explore this possibility, stably transfected human cell lines were established that harbour a tetracycline (Tet)-inducible system for controlled expression of the λ-Holin gene. The effect of the λ-Holin protein on eukaryotic cells was studied in vitro by applying several viability assays. We also investigated the effect of λ-Holin gene expression in vivo using a human breast cancer cell tumour xenograft as well as a syngeneic mammary adenocarcinoma mouse model. Results The λ-Holin-encoding gene was inducibly expressed in eukaryotic cells in vitro. Expression led to a substantial reduction of cell viability of more than 98%. In mouse models, λ-Holin-expressing tumour cell xenografts revealed significantly reduced growth rates in comparison to xenografts not expressing the λ-Holin gene. Conclusions The λ-Holin protein is cytotoxic for eukaryotic cells in vitro and inhibits tumour growth in vivo suggesting potential therapeutic use in cancer gene therapy. Copyright © 2005 John Wiley & Sons, Ltd.
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The cytotoxic activity of the bacteriophage λ‐Holin protein reduces tumour growth rates in mammary cancer cell xenograft models
The journal of gene medicine, 2006Co-Authors: Chukwuma A. Agu, Udo Bläsi, Reinhard Klein, Sonja Schwab, Marielle König-schuster, Petra Kodajova, Michael Ausserlechner, Bernhard Binishofer, Brian Salmons, Walter H. GünzburgAbstract:Background The potential use of gene therapy for cancer treatment is being intensively studied. One approach utilises the expression of genes encoding cytotoxic proteins. Such proteins can affect cellular viability, for example by inhibiting the translation machinery or disturbing membrane integrity. The bacteriophage Lambda (λ)-Holin protein is known to form a lesion in the cytoplasmic membrane of E. coli, triggering bacterial cell lysis and thereby enabling the release of new bacteriophage particles. The aim of this study was to evaluate whether the λ-Holin protein has a cytotoxic impact on eukaryotic cells and whether it holds potential as a new therapeutic protein for cancer gene therapy. Methods To explore this possibility, stably transfected human cell lines were established that harbour a tetracycline (Tet)-inducible system for controlled expression of the λ-Holin gene. The effect of the λ-Holin protein on eukaryotic cells was studied in vitro by applying several viability assays. We also investigated the effect of λ-Holin gene expression in vivo using a human breast cancer cell tumour xenograft as well as a syngeneic mammary adenocarcinoma mouse model. Results The λ-Holin-encoding gene was inducibly expressed in eukaryotic cells in vitro. Expression led to a substantial reduction of cell viability of more than 98%. In mouse models, λ-Holin-expressing tumour cell xenografts revealed significantly reduced growth rates in comparison to xenografts not expressing the λ-Holin gene. Conclusions The λ-Holin protein is cytotoxic for eukaryotic cells in vitro and inhibits tumour growth in vivo suggesting potential therapeutic use in cancer gene therapy. Copyright © 2005 John Wiley & Sons, Ltd.
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Functional analysis of the lysis genes of Staphylococcus aureus phage P68 in Escherichia coli
Microbiology, 2005Co-Authors: Marian Takáč, Angela Witte, Udo BläsiAbstract:Double-stranded DNA phages of both Gram-positive and Gram-negative bacteria typically use a Holin–endolysin system to achieve lysis of their host. In this study, the lysis genes of Staphylococcus aureus phage P68 were characterized. P68 gene lys16 was shown to encode a cell-wall-degrading enzyme, which causes cell lysis when externally added to clinical isolates of S. aureus. Another gene, hol15, was identified embedded in the −1 reading frame at the 3′ end of lys16. The deduced Hol15 protein has three putative transmembrane domains, and thus resembles class I Holins. An additional candidate Holin gene, hol12, was found downstream of the endolysin gene lys16 based on two predicted transmembrane domains of the encoded protein, which is a typical trait of class II Holins. The synthesis of either Hol12 or Hol15 resulted in growth retardation of Escherichia coli, and both hol15 and hol12 were able to complement a phage λ Sam mutation. The hol15 gene has a dual start motif beginning with the codons Met1-Lys2-Met3…. Evidence is presented that the hol15 gene encodes a lysis inhibitor (anti-Holin) and a lysis effector (actual Holin). As depolarization of the membrane converted the anti-Holin to a functional Holin, these studies suggested that hol15 functions as a typical dual start motif class I Holin. The unusual arrangement of the P68 lysis genes is discussed.
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Functional regulation of the Listeria monocytogenes bacteriophage A118 Holin by an intragenic inhibitor lacking the first transmembrane domain.
Molecular microbiology, 2003Co-Authors: Natasa Vukov, Udo Bläsi, Siegfried Scherer, Isabella Moll, Martin J. LoessnerAbstract:We have dissected the functional properties of the Holin encoded by Listeria monocytogenes bacteriophage A118. Native hol118 was cloned into lambdaDeltaSthf, devoid of the S Holin, and tested in an E. coli background. Surprisingly, it caused very late cell lysis, beginning at 80 min after induction. Immunological analyses demonstrated that Hol118 appears in the cytoplasmic membrane shortly after infection. The hol118 gene features a dual start motif similar to lambda S. Therefore, different N-terminally modified Hol118 variants were tested. However, in contrast to lambda S, inactivation of AUG-1 or AUG-2 showed no significant influence on lysis timing. In addition, Hol118-mediated lysis could not be triggered by energy poisons, indicating a functional regulation different from that of S. Toeprinting assays on hol118 mRNA revealed an unexpected translational start codon (AUG-3) at nucleotide position 40. We demonstrated by in vitro and in vivo approaches that the predicted Hol118(83) product is actually produced together with the full-length polypeptide. However, although the truncated Holin lacking its first transmembrane domain appeared in the cytoplasmic membrane, it was shown to be functionally deficient and unable to support lambda R-mediated lysis. In contrast, specific mutations introduced to abolish translation initiation at AUG-3 drastically accelerated lysis, pointing to an inhibitor function of Hol118(83). This hypothesis was supported by the observation that hol118(83) inhibited Holin function when expressed in trans. A deviation from the lambda S paradigm is proposed, which represents a new model of Holin functional regulation: the intragenic, in frame translated Hol118(83) product, which is devoid of its first transmembrane domain, acts as a functional inhibitor and constitutes a key part of the lysis clock of A118. Presence of the dominant inhibitor function also explains the long latent period of A118, where the onset of lysis takes about 70 min, more than twice the time needed by lambda.
Jianhe Sun - One of the best experts on this subject based on the ideXlab platform.
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combined antibacterial activity of phage lytic proteins Holin and lysin from streptococcus suis bacteriophage smp
Current Microbiology, 2012Co-Authors: Yibo Shi, Yaxian Yan, Hengan Wang, Jianhe SunAbstract:Development of novel antibacterial agents is required to control infection with multidrug-resistant Streptococcus suis. HolSMP and LySMP, the Holin and lysin of S. suis serotype 2 bacteriophage, named SMP, are responsible for lysis of host cells and release of progeny phage. HolSMP and LySMP expressed in Escherichia coli BL21(DE3) exerted efficient activity at 37 °C, pH 5.2, with addition of 0.8 % β-mercaptoethanol. Lytic spectra of purified HolSMP, LySMP or HolSMP + LySMP mixture were investigated. HolSMP, exhibiting a narrow lytic spectrum, was effective against Staphylococcus aureus and Bacillus subtilis, which were insensitive to LySMP. Moreover, HolSMP was identified as a promising antibacterial agent which was able to extend the spectrum of LySMP. The data suggest that combined use of Holin and lysin could be a candidate strategy for resolution of drug resistance.
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Characterization and determination of Holin protein of Streptococcus suis bacteriophage SMP in heterologous host
Virology journal, 2012Co-Authors: Yibo Shi, Yaxian Yan, Xiangpeng Meng, Hengan Wang, Jianhe SunAbstract:Background Holins are a group of phage-encoded membrane proteins that control access of phage-encoded endolysins to the peptidoglycan, and thereby trigger the lysis process at a precise time point as the 'lysis clock'. SMP is an isolated and characterized Streptococcus suis lytic phage. The aims of this study were to determine the Holin gene, HolSMP, in the genome of SMP, and characterized the function of Holin, HolSMP, in phage infection.
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Current advance in the topological structure and function of Holin encoded by bacteriophage lambda--a review
Wei sheng wu xue bao = Acta microbiologica Sinica, 2012Co-Authors: Yibo Shi, Jianhe SunAbstract:The Holin-lysin two-step lysis system widely exists in double stranded DNA bacteriophages for the release of progeny bacteriophage from an infected bacterial cell at the final stage of phage infection. Lambda bacteriophage is a prototype for studying Holin. The S gene in Lambda bacteriophage has a dual-start motif and encodes Holin S105 and antiHolin S107. Here, we reviewed the progress in topological structure of Holin from Lambda bacteriophage and its formation of membrane lethal holes. We also discussed the potential of the Holin in the control of bacterial infection.
Douglas K. Struck - One of the best experts on this subject based on the ideXlab platform.
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structure of the lethal phage pinhole
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Ting Pang, Karen G. Fleming, Douglas K. Struck, Christos G Savva, Ry YoungAbstract:Perhaps the simplest of biological timing systems, bacteriophage Holins accumulate during the phage morphogenesis period and then trigger to permeabilize the cytoplasmic membrane with lethal holes; thus, terminating the infection cycle. Canonical Holins form very large holes that allow nonspecific release of fully-folded proteins, but a recently discovered class of Holins, the pinHolins, make much smaller holes, or pinholes, that serve only to depolarize the membrane. Here, we interrogate the structure of the prototype pinHolin by negative-stain transmission electron-microscopy, cysteine-accessibility, and chemical cross-linking, as well as by computational approaches. Together, the results suggest that the pinHolin forms symmetric heptameric structures with the hydrophilic surface of one transmembrane domain lining the surface of a central channel ≈15 A in diameter. The structural model also suggests a rationale for the prehole state of the pinHolin, the persistence of which defines the duration of the viral latent period, and for the sensitivity of the Holin timing system to the energized state of the membrane.
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Thiol protection in membrane protein purifications: a study with phage Holins.
Analytical biochemistry, 2009Co-Authors: Jill S. Dewey, Douglas K. Struck, Ry YoungAbstract:Abstract The lambda Holin, or S105, is a small cytoplasmic membrane protein that controls the timing of host lysis. Using thiol-specific reagents, we determined that the single cysteine residue within S105 was heterogeneously modified during membrane extraction and subsequent immobilized metal ion chromatography. Here we describe the use of a specific and reversible thiol reagent, 2,2′-dithiodipyridine, to generate purified protein with its cysteine residues in the native thiol state. The 2,2′-dithiodipyridine protection protocol was also successfully used for another unrelated Holin, S 21 68, and should be generally useful for the purification of membrane proteins.
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The Holin of bacteriophage lambda forms rings with large diameter. Commentary
Molecular Microbiology, 2008Co-Authors: Mart Krupovic, John Deaton, Douglas K. Struck, Christos G Savva, Dennis H. Bamford, Rebecca L. White, Jill S. Dewey, Andreas Holzenburg, Ry YoungAbstract:Holins control the length of the infection cycle of tailed phages (the Caudovirales) by oligomerizing to form lethal holes in the cytoplasmic membrane at a time dictated by their primary structure. Nothing is currently known about the physical basis of their oligomerization or the structure of the oligomers formed by any known Holin. Here we use electron microscopy and single-particle analysis to characterize structures formed by the bacteriophage Holin (S105) in vitro. In non-ionic or mild zwitterionic detergents, purified S105, but not the lysis-defective variant S105 A52V , forms rings of at least two size classes, the most common having inner and outer diameters of 8.5 and 23 nm respectively, and containing approximately 72 S105 monomers. The height of these rings, 4 nm, closely matches the thickness of the lipid bilayer. The central channel is of unprecedented size for channels formed by integral membrane proteins, consistent with the non-specific nature of Holin-mediated membrane permeabilization. S105 present in detergent-solubilized rings and in inverted membrane vesicles showed similar sensitivities to proteolysis and cysteine-specific modification, suggesting that the rings are representative of the lethal holes formed by S105 to terminate the infection cycle and initiate lysis.
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The Holin of bacteriophage lambda forms rings with large diameter.
Molecular microbiology, 2008Co-Authors: Christos G Savva, John Deaton, Douglas K. Struck, Rebecca L. White, Jill S. Dewey, Andreas Holzenburg, Rye YoungAbstract:Summary Holins control the length of the infection cycle of tailed phages (the Caudovirales) by oligomerizing to form lethal holes in the cytoplasmic membrane at a time dictated by their primary structure. Nothing is currently known about the physical basis of their oligomerization or the structure of the oligomers formed by any known Holin. Here we use electron microscopy and single-particle analysis to character- ize structures formed by the bacteriophage l Holin (S105) in vitro. In non-ionic or mild zwitterionic detergents, purified S105, but not the lysis-defective variant S105A52V, forms rings of at least two size classes, the most common having inner and outer diameters of 8.5 and 23 nm respectively, and contain- ing approximately 72 S105 monomers. The height of these rings, 4 nm, closely matches the thickness of the lipid bilayer. The central channel is of unprec- edented size for channels formed by integral mem- brane proteins, consistent with the non-specific nature of Holin-mediated membrane permeabiliza- tion. S105 present in detergent-solubilized rings and in inverted membrane vesicles showed similar sen- sitivities to proteolysis and cysteine-specific modifi- cation, suggesting that the rings are representative of the lethal holes formed by S105 to terminate the infection cycle and initiate lysis.
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the pinHolin of lambdoid phage 21 control of lysis by membrane depolarization
Journal of Bacteriology, 2007Co-Authors: Taehyun Park, Douglas K. Struck, Chelsey A Dankenbring, Ry YoungAbstract:The phage 21 Holin, S 21 , forms small membrane holes that depolarize the membrane and is designated as a pinHolin, as opposed to large-hole-forming Holins, like S λ . PinHolins require secreted SAR endolysins, a pairing that may represent an intermediate in the evolution of canonical Holin-endolysin systems.
Yibo Shi - One of the best experts on this subject based on the ideXlab platform.
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combined antibacterial activity of phage lytic proteins Holin and lysin from streptococcus suis bacteriophage smp
Current Microbiology, 2012Co-Authors: Yibo Shi, Yaxian Yan, Hengan Wang, Jianhe SunAbstract:Development of novel antibacterial agents is required to control infection with multidrug-resistant Streptococcus suis. HolSMP and LySMP, the Holin and lysin of S. suis serotype 2 bacteriophage, named SMP, are responsible for lysis of host cells and release of progeny phage. HolSMP and LySMP expressed in Escherichia coli BL21(DE3) exerted efficient activity at 37 °C, pH 5.2, with addition of 0.8 % β-mercaptoethanol. Lytic spectra of purified HolSMP, LySMP or HolSMP + LySMP mixture were investigated. HolSMP, exhibiting a narrow lytic spectrum, was effective against Staphylococcus aureus and Bacillus subtilis, which were insensitive to LySMP. Moreover, HolSMP was identified as a promising antibacterial agent which was able to extend the spectrum of LySMP. The data suggest that combined use of Holin and lysin could be a candidate strategy for resolution of drug resistance.
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Characterization and determination of Holin protein of Streptococcus suis bacteriophage SMP in heterologous host
Virology journal, 2012Co-Authors: Yibo Shi, Yaxian Yan, Xiangpeng Meng, Hengan Wang, Jianhe SunAbstract:Background Holins are a group of phage-encoded membrane proteins that control access of phage-encoded endolysins to the peptidoglycan, and thereby trigger the lysis process at a precise time point as the 'lysis clock'. SMP is an isolated and characterized Streptococcus suis lytic phage. The aims of this study were to determine the Holin gene, HolSMP, in the genome of SMP, and characterized the function of Holin, HolSMP, in phage infection.
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Current advance in the topological structure and function of Holin encoded by bacteriophage lambda--a review
Wei sheng wu xue bao = Acta microbiologica Sinica, 2012Co-Authors: Yibo Shi, Jianhe SunAbstract:The Holin-lysin two-step lysis system widely exists in double stranded DNA bacteriophages for the release of progeny bacteriophage from an infected bacterial cell at the final stage of phage infection. Lambda bacteriophage is a prototype for studying Holin. The S gene in Lambda bacteriophage has a dual-start motif and encodes Holin S105 and antiHolin S107. Here, we reviewed the progress in topological structure of Holin from Lambda bacteriophage and its formation of membrane lethal holes. We also discussed the potential of the Holin in the control of bacterial infection.