The bifunctional peptidoglycan lysin of Streptococcus agalactiae bacteriophage B30
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A group B streptococcal (GBS) bacteriophage lysin gene was cloned and expressed in Escherichia coli. The purified recombinant enzyme, calculated to have a molecular mass of 49 677 Da, lysed GBS cells. The susceptibility of GBS cells to lysis by the enzyme depended upon the growth stage at which they were harvested, with early exponential phase cells most sensitive. Calcium ions enhanced the activity of the enzyme. The enzyme also lysed other beta-haemolytic streptococci, including groups A, C, E and G streptococci, but not common oral streptococci, including Streptococcus mutans. The generation of both reducing activity and N-terminal alanine residues during lysis indicated that the lysin is a bifunctional enzyme, possessing both glycosidase and endopeptidase activities. This is consistent with the presence of two conserved sequence domains, an Acm (acetylmuramidase) domain associated with lysozyme activity, and a CHAP (cysteine, histidine-dependent amidohydrolases/peptidases) domain associated with endopeptidase activity. Site-directed mutagenesis of conserved cysteine and histidine residues in the CHAP domain and conserved aspartate and glutamate residues in the Acm domain confirmed their importance for lysozyme and endopeptidase activity respectively.Keywords:
Lysin
Endopeptidase
Sonication
Polymyxin
Polymyxin B
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We confirmed the previous reports of Fleming, Nakamura et al. on the inability of lysozyme to lyse Micrococcus lysodeikticus cells at an acidic pH (3.0 - 3.5). In these conditions, lysozyme binds to the mucopolysaccharides of the cell wall without showing any lytic activity; lysis occurs at very high rate when pH is raised at neutral values by adding alkaline solutions. Our results were obtained by monitoring bacterial cultures both in aqueous solutions and on agar plates.
Lytic cycle
Micrococcus
Muramidase
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Journal Article Inhibitory Effect of Some Gaseous Hydrocarbons on the Cell-lysis of Micrococcus lysodeikticus by Egg-white Lysozyme Get access Kenji Watanabe, Kenji Watanabe Institute of Microbiology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka Search for other works by this author on: Oxford Academic Google Scholar Shigeru Takesue Shigeru Takesue Institute of Microbiology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka Search for other works by this author on: Oxford Academic Google Scholar Agricultural and Biological Chemistry, Volume 36, Issue 5, 1 May 1972, Pages 825–830, https://doi.org/10.1080/00021369.1972.10860331 Published: 01 May 1972 Article history Received: 22 October 1971 Published: 01 May 1972
Isobutane
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Lysins are efficient bacteria cell wall digesting enzymes encoded by DNA bacteriophage. Gram-positive bacteriophage lysins feature similar domain structure, high lytic efficiency, synergic antibacterial effect with antibiotics, rare neutralization by antibodies, less chance of developing drug-resistant strains, et al. The past decade has seen a considerable amount of research worldwidely focused on lysin, and lysins have been used successfully in a variety of animal models to control pathogenic antibiotic resistant bacteria found on mucosal surfaces and infected tissues. The great potential of lysins as an anti-infective agent prompted this review.
Lysin
Lytic cycle
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Lysin
Lytic cycle
Lysogenic cycle
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Endolysin was induced in Pseudomonas BAL‐31 infected with bacteriophage PM2 and was also associated with the purified virion. This enzyme required divalent cations for its activity, Ca 2+ being the most effective cation. Endolysin activity in the virion increased up to three‐fold upon disruption and the activity could be localized in the viral nucleocapsid. Thus the enzyme is localized within the virion. After purification of the structural proteins of bacteriophage PM2, only the nucleocapsid protein (III) had endolysin activity.
Lysin
Divalent
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Ralston, Doris J. (University of California, Berkeley) and Mary McIvor . Lysis-from-without of Staphylococcus aureus strains by combinations of specific phages and phage-induced lytic enzymes. J. Bacteriol. 88: 676–681. 1964—Several typing phages, adsorbed in sufficient concentrations to their homologous propagating strains, altered the cell surface so as to render the cells sensitive to rapid and synergistic lysis by extra-cellular additions of wall lysins. Lysis was effected both by lysins induced by the individual phages and by phage K 1 virolysin. Phage K 1 also rendered cells sensitive to the lysins of the typing phages. With the exception of lysins from PS 53, 70, and 77, none of the lysins nor purified phages tested separately caused significant lysis of living cells. Lysis-from-without in Staphylococcus aureus appears to be a stepwise process: sensitization by phage followed by digestion of the wall by lysin.
Lysin
Lytic cycle
Phage typing
Lysogenic cycle
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Streptococcus mutans BHT was grown in a synthetic medium containing radioactive thymidine to monitor deoxyribonucleic acid release. Kinetic experiments demonstrated that although lysozyme alone could not liberate deoxyribonucleic acid, cellular deoxyribonucleic acid was liberated from lysozyme-treated cells by addition of low concentrations of inorganic sodium salts. When the salts were tested for their ability to dislodge cell-bound tritiated lysozyme, the extent of the initial release of enzyme by individual anions correlated with the anion potency for deoxyribonucleic acid liberation (SCN- greater than ClO4- greater than I- greater than Br- greater than NO3- greater than Cl- greater than F-), although the total amount of lysozyme dislodged did not correspond directly with cell lysis. Differences in the effectiveness of anions (SCN-, HCO3-, Cl- and F-) in potentiating cell lysis could be enhanced or minimized by varying the lysozyme, anion, and bacterial cell concentrations. As the anion concentration was increased for each enzyme concentration and cell concentration, the lysis increased, in some cases markedly, until maximum levels of released deoxyribonucleic acid were attained. The maximum levels of lysis of SCN- and HCO3- were similar and were greater than those for Cl- and F-. In addition, the maximum levels were observed to increase for each of the anions as the concentration of lysozyme increased.
Muramidase
Thymidine
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Doughty , C. C. (University of Illinois College of Medicine, Chicago) and James A. Hayashi . Enzymatic properties of a phage-induced lysin affecting group A streptococci. J. Bacteriol. 83: 1058–1068. 1962.—Phage-induced lysis of group C streptococci releases into the medium a lysin which completely lyses group A streptococci. Partial purification of the lytic activity yields 47% of the original activity with a 17-fold purification. The activity was assayed by observing lysis of group A streptococci under standard conditions. The optimal pH range for lysis is from 6.0 to 6.7. A monovalent cation requirement satisfied by Na + , K + , or Li + is shown by the lysin. Lysis is stimulated by ethylenedi-aminetetraacetic acid (EDTA), chlortetracycline, streptomycin, and penicillin. It is inhibited by p -hydroxymercuribenzoate ( p HMB), and the inhibition is reversed by cysteine. Other inhibitors include ristocetin A and specific antisera against the lysin. Isolated group A streptococcal cell walls are partially lysed by massive amounts of lysin. This partial lysis is not affected by EDTA, p HMB, chlortetracycline, streptomycin, or ristocetin A. It is concluded that the enzymatic process of lysis of isolated cell walls is not identical to the more complex process resulting in lysis of intact cells.
Lysin
Lytic cycle
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The nature of the optical density of suspensions of Staph. aureus and M. luteus cells at various concentrations of chicken egg albumin lysozyme and two products of its chemical transformation was studied comparatively. The experiments were performed in 1/15 M Na-phosphate buffer at pH 6.2 and a temperature of 20-22 degrees C. It was shown that the decrease in the optical density of the suspensions observed at relatively low concentrations of lysozyme, i.e. 0.032-0.064 mg/ml, was due to lysis of both microbial species. The increase in the optical density of the suspensions at higher (0.5-2.0 mg/ml) concentrations of lysozyme was connected with formation of insoluble aggregates of an electrostatic character. Lysozyme in such aggregates is the positively charged component and the microbial cell material is the negatively charged component. When M. luteus strains are sensitive to lysozyme, the aggregates are formed from the cell fragments or lysis acid products. When Staph, aureus strains have higher resistance levels, the aggregates are formed from both the lysis products and the intact live cells which is of special interest.
Micrococcus luteus
Bovine serum albumin
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