1
|
Razew A, Laguri C, Vallet A, Bougault C, Kaus-Drobek M, Sabala I, Simorre JP. Staphylococcus aureus sacculus mediates activities of M23 hydrolases. Nat Commun 2023; 14:6706. [PMID: 37872144 PMCID: PMC10593780 DOI: 10.1038/s41467-023-42506-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 10/12/2023] [Indexed: 10/25/2023] Open
Abstract
Peptidoglycan, a gigadalton polymer, functions as the scaffold for bacterial cell walls and provides cell integrity. Peptidoglycan is remodelled by a large and diverse group of peptidoglycan hydrolases, which control bacterial cell growth and division. Over the years, many studies have focused on these enzymes, but knowledge on their action within peptidoglycan mesh from a molecular basis is scarce. Here, we provide structural insights into the interaction between short peptidoglycan fragments and the entire sacculus with two evolutionarily related peptidases of the M23 family, lysostaphin and LytM. Through nuclear magnetic resonance, mass spectrometry, information-driven modelling, site-directed mutagenesis and biochemical approaches, we propose a model in which peptidoglycan cross-linking affects the activity, selectivity and specificity of these two structurally related enzymes differently.
Collapse
Affiliation(s)
- Alicja Razew
- Universite Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 avenue des Martyrs-CS10090, Grenoble cedex 9, 38044, France
- International Institute of Molecular and Cell Biology in Warsaw, 4 Ks. Trojdena Street, 02-109, Warsaw, Poland
- Laboratory of Protein Engineering, Mossakowski Medical Research Institute, Polish Academy of Sciences, 5 Pawinskiego Street, 02-106, Warsaw, Poland
| | - Cedric Laguri
- Universite Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 avenue des Martyrs-CS10090, Grenoble cedex 9, 38044, France
| | - Alicia Vallet
- Universite Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 avenue des Martyrs-CS10090, Grenoble cedex 9, 38044, France
| | - Catherine Bougault
- Universite Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 avenue des Martyrs-CS10090, Grenoble cedex 9, 38044, France
| | - Magdalena Kaus-Drobek
- Laboratory of Protein Engineering, Mossakowski Medical Research Institute, Polish Academy of Sciences, 5 Pawinskiego Street, 02-106, Warsaw, Poland
| | - Izabela Sabala
- International Institute of Molecular and Cell Biology in Warsaw, 4 Ks. Trojdena Street, 02-109, Warsaw, Poland.
- Laboratory of Protein Engineering, Mossakowski Medical Research Institute, Polish Academy of Sciences, 5 Pawinskiego Street, 02-106, Warsaw, Poland.
| | - Jean-Pierre Simorre
- Universite Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 avenue des Martyrs-CS10090, Grenoble cedex 9, 38044, France.
| |
Collapse
|
2
|
Grob G, Hemmerle M, Yakobov N, Mahmoudi N, Fischer F, Senger B, Becker HD. tRNA-dependent addition of amino acids to cell wall and membrane components. Biochimie 2022; 203:93-105. [DOI: 10.1016/j.biochi.2022.09.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 09/23/2022] [Accepted: 09/26/2022] [Indexed: 11/16/2022]
|
3
|
Wysocka A, Łężniak Ł, Jagielska E, Sabała I. Electrostatic Interaction with the Bacterial Cell Envelope Tunes the Lytic Activity of Two Novel Peptidoglycan Hydrolases. Microbiol Spectr 2022; 10:e0045522. [PMID: 35467396 PMCID: PMC9241647 DOI: 10.1128/spectrum.00455-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 04/04/2022] [Indexed: 12/14/2022] Open
Abstract
Peptidoglycan (PG) hydrolases, due to their crucial role in the metabolism of the bacterial cell wall (CW), are increasingly being considered suitable targets for therapies, and a potent alternative to conventional antibiotics. In the light of contradictory data reported, detailed mechanism of regulation of enzymes activity based on electrostatic interactions between hydrolase molecule and bacterial CW surface remains unknown. Here, we report a comprehensive study on this phenomenon using as a model two novel PG hydrolases, SpM23_A, and SpM23_B, which although share the same bacterial host, similarities in sequence conservation, domain architecture, and structure, display surprisingly distinct net charges (in 2D electrophoresis, pI 6.8, and pI 9.7, respectively). We demonstrate a strong correlation between hydrolases surface net charge and the enzymes activity by modulating the charge of both, enzyme molecule and bacterial cell surface. Teichoic acids, anionic polymers present in the bacterial CW, are shown to be involved in the mechanism of enzymes activity regulation by the electrostatics-based interplay between charged bacterial envelope and PG hydrolases. These data serve as a hint for the future development of chimeric PG hydrolases of desired antimicrobial specificity. IMPORTANCE This study shows direct relationship between the surface charge of two recently described enzymes, SpM23_A and SpM23_B, and bacterial cell walls. We demonstrate that by (i) surface charge probing of bacterial strains collection, (ii) reduction of the net charge of the positively charged enzyme, and (iii) altering the net charge of the bacterial surface by modifying the content and composition of teichoic acids. In all cases, we observed that lytic activity and binding strength of SpM23 enzymes, are regulated by electrostatic interactions with the bacterial cell envelope and that this interaction contributes to the determination of the spectrum of susceptible bacterial species. Moreover, we revealed the regulatory role of charged cell wall components, namely, teichoic and lipoteichoic acids, over the SpM23 enzymes. We believe that our findings make an important contribution to understand the means of hydrolases activity regulation in the complex environment of the bacterial cell wall.
Collapse
Affiliation(s)
- Alicja Wysocka
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Łukasz Łężniak
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Elżbieta Jagielska
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
- Mossakowski Medical Research Institute Polish Academy of Sciences, Warsaw, Poland
| | - Izabela Sabała
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
- Mossakowski Medical Research Institute Polish Academy of Sciences, Warsaw, Poland
| |
Collapse
|
4
|
Comparative Transcriptome Analysis Reveals Differentially Expressed Genes Related to Antimicrobial Properties of Lysostaphin in Staphylococcus aureus. Antibiotics (Basel) 2022; 11:antibiotics11020125. [PMID: 35203727 PMCID: PMC8868216 DOI: 10.3390/antibiotics11020125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/07/2022] [Accepted: 01/11/2022] [Indexed: 11/17/2022] Open
Abstract
Comparative transcriptome analysis and de novo short-read assembly of S. aureus Newman strains revealed significant transcriptional changes in response to the exposure to triple-acting staphylolytic peptidoglycan hydrolase (PGH) 1801. Most altered transcriptions were associated with the membrane, cell wall, and related genes, including amidase, peptidase, holin, and phospholipase D/transphosphatidylase. The differential expression of genes obtained from RNA-seq was confirmed by reverse transcription quantitative PCR. Moreover, some of these gene expression changes were consistent with the observed structural perturbations at the DNA and RNA levels. These structural changes in the genes encoding membrane/cell surface proteins and altered gene expressions are the candidates for resistance to these novel antimicrobials. The findings in this study could provide insight into the design of new antimicrobial agents.
Collapse
|
5
|
Wysocka A, Jagielska E, Łężniak Ł, Sabała I. Two New M23 Peptidoglycan Hydrolases With Distinct Net Charge. Front Microbiol 2021; 12:719689. [PMID: 34630350 PMCID: PMC8498115 DOI: 10.3389/fmicb.2021.719689] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 08/16/2021] [Indexed: 11/13/2022] Open
Abstract
Bacterial peptidoglycan hydrolases play an essential role in cell wall metabolism during bacterial growth, division, and elongation (autolysins) or in the elimination of closely related species from the same ecological niche (bacteriocins). Most studies concerning the peptidoglycan hydrolases present in Gram-positive bacteria have focused on clinically relevant Staphylococcus aureus or the model organism Bacillus subtilis, while knowledge relating to other species remains limited. Here, we report two new peptidoglycan hydrolases from the M23 family of metallopeptidases derived from the same staphylococcal species, Staphylococcus pettenkoferi. They share modular architecture, significant sequence identity (60%), catalytic and binding residue conservation, and similar modes of activation, but differ in gene distribution, putative biological role, and, strikingly, in their isoelectric points (pIs). One of the peptides has a high pI, similar to that reported for all M23 peptidases evaluated to date, whereas the other displays a low pI, a unique feature among M23 peptidases. Consequently, we named them SpM23_B (Staphylococcus pettenkoferi M23 "Basic") and SpM23_A (Staphylococcus pettenkoferi M23 "Acidic"). Using genetic and biochemical approaches, we have characterized these two novel lytic enzymes, both in vitro and in their physiological context. Our study presents a detailed characterization of two novel and clearly distinct peptidoglycan hydrolases to understand their role in bacterial physiology.
Collapse
Affiliation(s)
- Alicja Wysocka
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Elżbieta Jagielska
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Łukasz Łężniak
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Izabela Sabała
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| |
Collapse
|
6
|
Kharadi RR, Sundin GW. Cyclic-di-GMP Regulates Autoaggregation Through the Putative Peptidoglycan Hydrolase, EagA, and Regulates Transcription of the znuABC Zinc Uptake Gene Cluster in Erwinia amylovora. Front Microbiol 2020; 11:605265. [PMID: 33281804 PMCID: PMC7705223 DOI: 10.3389/fmicb.2020.605265] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 10/27/2020] [Indexed: 11/24/2022] Open
Abstract
Erwinia amylovora is the causal agent of fire blight, an economically impactful disease that affects apple and pear production worldwide. E. amylovora pathogenesis is comprised of distinct type III secretion-dependent and biofilm-dependent stages. Alterations in the intracellular levels of cyclic-di-GMP (c-di-GMP) regulate the transition between the different stages of infection in E. amylovora. We previously reported that hyper-elevation of c-di-GMP levels in E. amylovora Ea1189, resulting from the deletion of all three c-di-GMP specific phosphodiesterase genes (Ea1189ΔpdeABC), resulted in an autoaggregation phenotype. The two major exopolysaccharides, amylovoran and cellulose, were also shown to partially contribute to autoaggregation. In this study, we aimed to identify the c-di-GMP dependent factor(s) that contributes to autoaggregation. We conducted a transposon mutant screen in Ea1189ΔpdeABC and selected for loss of autoaggregation. Our search identified a peptidoglycan hydrolase, specifically, a D, D-endopeptidase of the metallopeptidase class, EagA (Erwiniaaggregation factor A), that was found to physiologically contribute to autoaggregation in a c-di-GMP dependent manner. The production of amylovoran was also positively affected by EagA levels. An eagA deletion mutant (Ea1189ΔeagA) was significantly reduced in virulence compared to the wild type E. amylovora Ea1189. eagA is part of the znuABC zinc uptake gene cluster and is located within an operon downstream of znuA. The znuAeagA/znuCB gene cluster was transcriptionally regulated by elevated levels of c-di-GMP as well as by the zinc-dependent transcriptional repressor Zur. We also observed that with an influx of Zn2+ in the environment, the transcription of the znuAeagA/znuBC gene cluster is regulated by both Zur and a yet to be characterized c-di-GMP dependent pathway.
Collapse
Affiliation(s)
- Roshni R Kharadi
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, United States
| | - George W Sundin
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, United States
| |
Collapse
|
7
|
Functional Identification of Serine Hydroxymethyltransferase as a Key Gene Involved in Lysostaphin Resistance and Virulence Potential of Staphylococcus aureus Strains. Int J Mol Sci 2020; 21:ijms21239135. [PMID: 33266291 PMCID: PMC7731198 DOI: 10.3390/ijms21239135] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 11/22/2020] [Accepted: 11/26/2020] [Indexed: 12/17/2022] Open
Abstract
Gaining an insight into the mechanism underlying antimicrobial-resistance development in Staphylococcus aureus is crucial for identifying effective antimicrobials. We isolated S. aureus sequence type 72 from a patient in whom the S. aureus infection was highly resistant to various antibiotics and lysostaphin, but no known resistance mechanisms could explain the mechanism of lysostaphin resistance. Genome-sequencing followed by subtractive and functional genomics revealed that serine hydroxymethyltransferase (glyA or shmT gene) plays a key role in lysostaphin resistance. Serine hydroxymethyltransferase (SHMT) is indispensable for the one-carbon metabolism of serine/glycine interconversion and is linked to folate metabolism. Functional studies revealed the involvement of SHMT in lysostaphin resistance, as ΔshmT was susceptible to the lysostaphin, while complementation of the knockout expressing shmT restored resistance against lysostaphin. In addition, the ΔshmT showed reduced virulence under in vitro (mammalian cell lines infection) and in vivo (wax-worm infection) models. The SHMT inhibitor, serine hydroxymethyltransferase inhibitor 1 (SHIN1), protected the 50% of the wax-worm infected with wild type S. aureus. These results suggest SHMT is relevant to the extreme susceptibility to lysostaphin and the host immune system. Thus, the current study established that SHMT plays a key role in lysostaphin resistance development and in determining the virulence potential of multiple drug-resistant S. aureus.
Collapse
|
8
|
Shadrin VS, Machulin AV, Dorofeeva LV, Chernyshov SV, Mikoulinskaia GV. Lysis of cells of diverse bacteria by l,d-peptidases of Escherichia coli bacteriophages RB43, RB49 and T5. J Appl Microbiol 2020; 130:1902-1912. [PMID: 33107183 DOI: 10.1111/jam.14910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 10/07/2020] [Accepted: 10/22/2020] [Indexed: 01/03/2023]
Abstract
AIMS The objective of this work was to study the antibacterial specificity and antibacterial effect of endolysins isolated from colibacteriophages RB43, RB49 and T5-as manifested on the exponential and stationary cell cultures of diverse bacteria depending on the growth stage, structure of peptidoglycan (PG) and antibiotic resistance. METHODS AND RESULTS Enzyme activity was assayed by the spectrophotometric method. Antimicrobial activity was estimated by the number of colony forming units (CFUs), with the results represented as logarithmic units. Morphological examination of bacterial cells was conducted using phase-contrast and scanning electron microscopy. The enzymes EndoT5, endolysin of bacteriophage T5, EndoRB43, endolysin of bacteriophage RB43 and EndoRB49, endolysin of bacteriophage RB49 turned out to be much less bacteriospecific than the corresponding Escherichia coli phages; they lysed bacteria of the genera Bacillus, Cellulomonas and Sporosarcina, whose PGs had different structures (A1γ, A4α and A4β) and chemical modifications (amidation). The specific lytic activity of phage enzymes was independent of the antibiotic resistance of bacterial cells and was higher when the cells were in the exponential, rather than stationary, growth phase. The analysis of morphological changes showed that the intermediate stage of the endolysin-induced lysis of bacterial cells was the formation of spheroplasts and protoplasts. CONCLUSIONS Endolysins of colibacteriophages RB49, RB43 and T5 have a wide spectrum of antibacterial action, which includes a number of diverse micro-organisms with different PG structures. SIGNIFICANCE AND IMPACT OF THE STUDY This is a study of the bacterial selectivity of enzymes degrading bacterial cell wall in relation to the chemical structure of PG. It is shown that endolysins of bacteriophages RB49 and RB43 efficiently lyse cell wall of Gram-positive bacteria of the genus Bacillus and Gram-negative bacteria of the genus Pseudomonas (including an antibiotic-resistant strain). The number of bacterial cells is reduced by 3-6 orders of magnitude, which indicates good prospects for using these enzymes in biotechnology.
Collapse
Affiliation(s)
- V S Shadrin
- Branch of Shemyakin & Ovchinnikov's Institute of Bioorganic Chemistry RAS, Pushchino, Russia
| | - A V Machulin
- Skryabin's Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Federal Research Center 'Pushchino Scientific Center for Biological Research of the, Russian Academy of Sciences', Pushchino, Russia
| | - L V Dorofeeva
- Skryabin's Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Federal Research Center 'Pushchino Scientific Center for Biological Research of the, Russian Academy of Sciences', Pushchino, Russia
| | - S V Chernyshov
- Branch of Shemyakin & Ovchinnikov's Institute of Bioorganic Chemistry RAS, Pushchino, Russia
| | - G V Mikoulinskaia
- Branch of Shemyakin & Ovchinnikov's Institute of Bioorganic Chemistry RAS, Pushchino, Russia
| |
Collapse
|
9
|
Grishin AV, Karyagina AS, Vasina DV, Vasina IV, Gushchin VA, Lunin VG. Resistance to peptidoglycan-degrading enzymes. Crit Rev Microbiol 2020; 46:703-726. [PMID: 32985279 DOI: 10.1080/1040841x.2020.1825333] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The spread of bacterial strains resistant to commonly used antibiotics urges the development of novel antibacterial compounds. Ideally, these novel antimicrobials should be less prone to the development of resistance. Peptidoglycan-degrading enzymes are a promising class of compounds with a fundamentally different mode of action compared to traditionally used antibiotics. The difference in the mechanism of action implies differences both in the mechanisms of resistance and the chances of its emergence. To critically assess the potential of resistance development to peptidoglycan-degrading enzymes, we review the available evidence for the development of resistance to these enzymes in vitro, along with the known mechanisms of resistance to lysozyme, bacteriocins, autolysins, and phage endolysins. We conclude that genetic determinants of resistance to peptidoglycan-degrading enzymes are unlikely to readily emerge de novo. However, resistance to these enzymes would probably spread by the horizontal transfer between intrinsically resistant and susceptible species. Finally, we speculate that the higher cost of the therapeutics based on peptidoglycan degrading enzymes compared to classical antibiotics might result in less misuse, which in turn would lead to lower selective pressure, making these antibacterials less prone to resistance development.
Collapse
Affiliation(s)
- Alexander V Grishin
- N.F. Gamaleya National Research Center for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Moscow, Russia.,All-Russia Research Institute of Agricultural Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Anna S Karyagina
- N.F. Gamaleya National Research Center for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Moscow, Russia.,All-Russia Research Institute of Agricultural Biotechnology, Russian Academy of Sciences, Moscow, Russia.,A.N. Belozersky Institute of Physical and Chemical Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Daria V Vasina
- N.F. Gamaleya National Research Center for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Moscow, Russia.,A.N. Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Irina V Vasina
- N.F. Gamaleya National Research Center for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Moscow, Russia
| | - Vladimir A Gushchin
- N.F. Gamaleya National Research Center for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Moscow, Russia.,Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Vladimir G Lunin
- N.F. Gamaleya National Research Center for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, Moscow, Russia.,All-Russia Research Institute of Agricultural Biotechnology, Russian Academy of Sciences, Moscow, Russia
| |
Collapse
|
10
|
Willing S, Dyer E, Schneewind O, Missiakas D. FmhA and FmhC of Staphylococcus aureus incorporate serine residues into peptidoglycan cross-bridges. J Biol Chem 2020; 295:13664-13676. [PMID: 32759309 PMCID: PMC7521636 DOI: 10.1074/jbc.ra120.014371] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 08/03/2020] [Indexed: 12/16/2022] Open
Abstract
Staphylococcal peptidoglycan is characterized by pentaglycine cross-bridges that are cross-linked between adjacent wall peptides by penicillin-binding proteins to confer robustness and flexibility. In Staphylococcus aureus, pentaglycine cross-bridges are synthesized by three proteins: FemX adds the first glycine, and the homodimers FemA and FemB sequentially add two Gly-Gly dipeptides. Occasionally, serine residues are also incorporated into the cross-bridges by enzymes that have heretofore not been identified. Here, we show that the FemA/FemB homologues FmhA and FmhC pair with FemA and FemB to incorporate Gly-Ser dipeptides into cross-bridges and to confer resistance to lysostaphin, a secreted bacteriocin that cleaves the pentaglycine cross-bridge. FmhA incorporates serine residues at positions 3 and 5 of the cross-bridge. In contrast, FmhC incorporates a single serine at position 5. Serine incorporation also lowers resistance toward oxacillin, an antibiotic that targets penicillin-binding proteins, in both methicillin-sensitive and methicillin-resistant strains of S. aureus FmhC is encoded by a gene immediately adjacent to lytN, which specifies a hydrolase that cleaves the bond between the fifth glycine of cross-bridges and the alanine of the adjacent stem peptide. In this manner, LytN facilitates the separation of daughter cells. Cell wall damage induced upon lytN overexpression can be alleviated by overexpression of fmhC. Together, these observations suggest that FmhA and FmhC generate peptidoglycan cross-bridges with unique serine patterns that provide protection from endogenous murein hydrolases governing cell division and from bacteriocins produced by microbial competitors.
Collapse
Affiliation(s)
- Stephanie Willing
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA
| | - Emma Dyer
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA
| | - Olaf Schneewind
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA
| | - Dominique Missiakas
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA; Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Lemont, Illinois, USA.
| |
Collapse
|
11
|
Abstract
Dating back to the 1960s, initial studies on the staphylococcal cell wall were driven by the need to clarify the mode of action of the first antibiotics and the resistance mechanisms developed by the bacteria. During the following decades, the elucidation of the biosynthetic path and primary composition of staphylococcal cell walls was propelled by advances in microbial cell biology, specifically, the introduction of high-resolution analytical techniques and molecular genetic approaches. The field of staphylococcal cell wall gradually gained its own significance as the complexity of its chemical structure and involvement in numerous cellular processes became evident, namely its versatile role in host interactions, coordination of cell division and environmental stress signaling.This chapter includes an updated description of the anatomy of staphylococcal cell walls, paying particular attention to information from the last decade, under four headings: high-resolution analysis of the Staphylococcus aureus peptidoglycan; variations in peptidoglycan composition; genetic determinants and enzymes in cell wall synthesis; and complex functions of cell walls. The latest contributions to a more precise picture of the staphylococcal cell envelope were possible due to recently developed state-of-the-art microscopy and spectroscopy techniques and to a wide combination of -omics approaches, that are allowing to obtain a more integrative view of this highly dynamic structure.
Collapse
Affiliation(s)
- Rita Sobral
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | | |
Collapse
|
12
|
Mitkowski P, Jagielska E, Nowak E, Bujnicki JM, Stefaniak F, Niedziałek D, Bochtler M, Sabała I. Structural bases of peptidoglycan recognition by lysostaphin SH3b domain. Sci Rep 2019; 9:5965. [PMID: 30979923 PMCID: PMC6461655 DOI: 10.1038/s41598-019-42435-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 03/29/2019] [Indexed: 11/09/2022] Open
Abstract
Staphylococcus simulans lysostaphin cleaves pentaglycine cross-bridges between stem peptides in the peptidoglycan of susceptible staphylococci, including S. aureus. This enzyme consists of an N-terminal catalytic domain and a cell wall binding domain (SH3b), which anchors the protein to peptidoglycan. Although structures of SH3bs from lysostaphin are available, the binding modes of peptidoglycan to these domains are still unclear. We have solved the crystal structure of the lysostaphin SH3b domain in complex with a pentaglycine peptide representing the peptidoglycan cross-bridge. The structure identifies a groove between β1 and β2 strands as the pentaglycine binding site. The structure suggests that pentaglycine specificity of the SH3b arises partially directly by steric exclusion of Cβ atoms in the ligand and partially indirectly due to the selection of main chain conformations that are easily accessible for glycine, but not other amino acid residues. We have revealed further interactions of SH3b with the stem peptides with the support of bioinformatics tools. Based on the structural data we have attempted engineering of the domain specificity and have investigated the relevance of the introduced substitutions on the domain binding and specificity, also in the contexts of the mature lysostaphin and of its bacteriolytic activity.
Collapse
Affiliation(s)
- Paweł Mitkowski
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Elżbieta Jagielska
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Elżbieta Nowak
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Janusz M Bujnicki
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland.,Laboratory of Bioinformatics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
| | - Filip Stefaniak
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Dorota Niedziałek
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, Warsaw, Poland
| | - Matthias Bochtler
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland.,Institute of Biochemistry and Biophysics Polish Academy of Sciences, Warsaw, Poland
| | - Izabela Sabała
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland.
| |
Collapse
|
13
|
The peptidoglycan and biofilm matrix of Staphylococcus epidermidis undergo structural changes when exposed to human platelets. PLoS One 2019; 14:e0211132. [PMID: 30682094 PMCID: PMC6347161 DOI: 10.1371/journal.pone.0211132] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 01/02/2019] [Indexed: 11/19/2022] Open
Abstract
Staphylococcus epidermidis is a bacterium frequently isolated from contaminated platelet concentrates (PCs), a blood product used to treat bleeding disorders in transfusion patients. PCs offer an accidental niche for colonization of S. epidermidis by forming biofilms and thus avoiding clearance by immune factors present in this milieu. Using biochemical and microscopy techniques, we investigated the structural changes of the peptidoglycan (PG) and the biofilm matrix of S. epidermidis biofilms formed in whole-blood derived PCs compared to biofilms grown in glucose-supplemented trypticase soy broth (TSBg). Both, the PG and the biofilm matrix are primary mechanisms of defense against environmental stress. Here we show that in PCs, the S. epidermidis biofilm matrix is mainly of a proteinaceous nature with extracellular DNA, in contrast to the predominant polysaccharide nature of the biofilm matrix formed in TSBg cultures. PG profile studies demonstrated that the PG of biofilm cells remodels during PC storage displaying fewer muropeptides variants than those observed in TSBg. The PG muropeptides contain two chemical modifications (amidation and O-acetylation) previously associated with resistance to antimicrobial agents by other staphylococci. Our study highlights two key structural features of S. epidermidis that are remodeled when exposed to human platelets and could be used as targets to reduce septic transfusions events.
Collapse
|
14
|
Love MJ, Bhandari D, Dobson RCJ, Billington C. Potential for Bacteriophage Endolysins to Supplement or Replace Antibiotics in Food Production and Clinical Care. Antibiotics (Basel) 2018; 7:E17. [PMID: 29495476 PMCID: PMC5872128 DOI: 10.3390/antibiotics7010017] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 02/06/2018] [Accepted: 02/23/2018] [Indexed: 01/21/2023] Open
Abstract
There is growing concern about the emergence of bacterial strains showing resistance to all classes of antibiotics commonly used in human medicine. Despite the broad range of available antibiotics, bacterial resistance has been identified for every antimicrobial drug developed to date. Alarmingly, there is also an increasing prevalence of multidrug-resistant bacterial strains, rendering some patients effectively untreatable. Therefore, there is an urgent need to develop alternatives to conventional antibiotics for use in the treatment of both humans and food-producing animals. Bacteriophage-encoded lytic enzymes (endolysins), which degrade the cell wall of the bacterial host to release progeny virions, are potential alternatives to antibiotics. Preliminary studies show that endolysins can disrupt the cell wall when applied exogenously, though this has so far proven more effective in Gram-positive bacteria compared with Gram-negative bacteria. Their potential for development is furthered by the prospect of bioengineering, and aided by the modular domain structure of many endolysins, which separates the binding and catalytic activities into distinct subunits. These subunits can be rearranged to create novel, chimeric enzymes with optimized functionality. Furthermore, there is evidence that the development of resistance to these enzymes may be more difficult compared with conventional antibiotics due to their targeting of highly conserved bonds.
Collapse
Affiliation(s)
- Michael J Love
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch 8041, New Zealand.
| | - Dinesh Bhandari
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch 8041, New Zealand.
- Institute of Environmental Science and Research, Christchurch 8041, New Zealand.
| | - Renwick C J Dobson
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch 8041, New Zealand.
- Department of Biochemistry and Molecular Biology, University of Melbourne, Melbourne 3052, Australia.
| | - Craig Billington
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch 8041, New Zealand.
- Institute of Environmental Science and Research, Christchurch 8041, New Zealand.
| |
Collapse
|
15
|
Efficient Killing of Planktonic and Biofilm-Embedded Coagulase-Negative Staphylococci by Bactericidal Protein P128. Antimicrob Agents Chemother 2017; 61:AAC.00457-17. [PMID: 28559263 DOI: 10.1128/aac.00457-17] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 05/21/2017] [Indexed: 01/10/2023] Open
Abstract
Coagulase-negative staphylococci (CoNS) are the major causative agents of foreign-body-related infections, including catheter-related bloodstream infections. Because of the involvement of biofilms, foreign-body-related infections are difficult to treat. P128, a chimeric recombinant phage-derived ectolysin, has been shown to possess bactericidal activity on strains of Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA). We tested the killing potential of P128 on three clinically significant species of CoNS, S. epidermidis, S. haemolyticus, and S. lugdunensis, under a variety of physiological conditions representing growing and nongrowing states. The MIC90 and minimum bactericidal concentration at which 90% of strains tested are killed (MBC90) of P128 on 62 clinical strains of CoNS were found to be 16 and 32 μg/ml (0.58 and 1.16 μM), respectively, demonstrating the bactericidal nature of P128 on CoNS strains. Serum showed a potentiating effect on P128 inhibition, as indicated by 4- to 32-fold lower MIC values observed in serum. P128 caused a rapid loss of viability in all CoNS strains tested. Persisters of CoNS that were enriched in the presence of vancomycin or daptomycin were killed by P128 at 1× the MIC in a rapid manner. Low concentrations of P128 caused a 2- to 5-log reduction in CFU in stationary-phase or poorly metabolizing CoNS cultures. P128 at low concentrations eliminated CoNS biofilms in microtiter plates and on the surface of catheters. Combinations of P128 and standard-of-care (SoC) antibiotics were highly synergistic in inhibiting growth in preformed biofilms. Potent activity on planktonic cells, persisters, and biofilms of CoNS suggests that P128 is a promising candidate for the clinical development of treatments for foreign-body-related and other CoNS infections.
Collapse
|
16
|
Shepherd J, Ibba M. Bacterial transfer RNAs. FEMS Microbiol Rev 2015; 39:280-300. [PMID: 25796611 DOI: 10.1093/femsre/fuv004] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/21/2015] [Indexed: 11/14/2022] Open
Abstract
Transfer RNA is an essential adapter molecule that is found across all three domains of life. The primary role of transfer RNA resides in its critical involvement in the accurate translation of messenger RNA codons during protein synthesis and, therefore, ultimately in the determination of cellular gene expression. This review aims to bring together the results of intensive investigations into the synthesis, maturation, modification, aminoacylation, editing and recycling of bacterial transfer RNAs. Codon recognition at the ribosome as well as the ever-increasing number of alternative roles for transfer RNA outside of translation will be discussed in the specific context of bacterial cells.
Collapse
Affiliation(s)
- Jennifer Shepherd
- Department of Microbiology and the Center for RNA Biology, Ohio State University, Columbus, Ohio 43210, USA
| | - Michael Ibba
- Department of Microbiology and the Center for RNA Biology, Ohio State University, Columbus, Ohio 43210, USA
| |
Collapse
|
17
|
Sundarrajan S, Raghupatil J, Vipra A, Narasimhaswamy N, Saravanan S, Appaiah C, Poonacha N, Desai S, Nair S, Bhatt RN, Roy P, Chikkamadaiah R, Durgaiah M, Sriram B, Padmanabhan S, Sharma U. Bacteriophage-derived CHAP domain protein, P128, kills Staphylococcus cells by cleaving interpeptide cross-bridge of peptidoglycan. Microbiology (Reading) 2014; 160:2157-2169. [DOI: 10.1099/mic.0.079111-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
P128 is an anti-staphylococcal protein consisting of the Staphylococcus aureus phage-K-derived tail-associated muralytic enzyme (TAME) catalytic domain (Lys16) fused with the cell-wall-binding SH3b domain of lysostaphin. In order to understand the mechanism of action and emergence of resistance to P128, we isolated mutants of Staphylococcus spp., including meticillin-resistant Staphylococcus aureus (MRSA), resistant to P128. In addition to P128, the mutants also showed resistance to Lys16, the catalytic domain of P128. The mutants showed loss of fitness as shown by reduced rate of growth in vitro. One of the mutants tested was found to show reduced virulence in animal models of S. aureus septicaemia suggesting loss of fitness in vivo as well. Analysis of the antibiotic sensitivity pattern showed that the mutants derived from MRSA strains had become sensitive to meticillin and other β-lactams. Interestingly, the mutant cells were resistant to the lytic action of phage K, although the phage was able to adsorb to these cells. Sequencing of the femA gene of three P128-resistant mutants showed either a truncation or deletion in femA, suggesting that improper cross-bridge formation in S. aureus could be causing resistance to P128. Using glutathione S-transferase (GST) fusion peptides as substrates it was found that both P128 and Lys16 were capable of cleaving a pentaglycine sequence, suggesting that P128 might be killing S. aureus by cleaving the pentaglycine cross-bridge of peptidoglycan. Moreover, peptides corresponding to the reported cross-bridge of Staphylococcus haemolyticus (GGSGG, AGSGG), which were not cleaved by lysostaphin, were cleaved efficiently by P128. This was also reflected in high sensitivity of S. haemolyticus to P128. This showed that in spite of sharing a common mechanism of action with lysostaphin, P128 has unique properties, which allow it to act on certain lysostaphin-resistant Staphylococcus strains.
Collapse
Affiliation(s)
- Sudarson Sundarrajan
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| | - Junjappa Raghupatil
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| | - Aradhana Vipra
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| | - Nagalakshmi Narasimhaswamy
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| | - Sanjeev Saravanan
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| | - Chemira Appaiah
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| | - Nethravathi Poonacha
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| | - Srividya Desai
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| | - Sandhya Nair
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| | - Rajagopala Narayana Bhatt
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| | - Panchali Roy
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| | - Ravisha Chikkamadaiah
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| | - Murali Durgaiah
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| | - Bharathi Sriram
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| | - Sriram Padmanabhan
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| | - Umender Sharma
- GangaGen Biotechnologies Pvt. Ltd, No. 12 5th cross, Raghavendra layout, Tumkur road, Yeshwantpur, Bangalore 560022, India
| |
Collapse
|
18
|
Shepherd J, Ibba M. Direction of aminoacylated transfer RNAs into antibiotic synthesis and peptidoglycan-mediated antibiotic resistance. FEBS Lett 2013; 587:2895-904. [PMID: 23907010 DOI: 10.1016/j.febslet.2013.07.036] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 07/17/2013] [Indexed: 12/30/2022]
Abstract
Prokaryotic aminoacylated-transfer RNAs often need to be efficiently segregated between translation and other cellular biosynthetic pathways. Many clinically relevant bacteria, including Streptococcus pneumoniae, Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeruginosa direct some aminoacylated-tRNA species into peptidoglycan biosynthesis and/or membrane phospholipid modification. Subsequent indirect peptidoglycan cross-linkage or change in membrane permeability is often a prerequisite for high-level antibiotic resistance. In Streptomycetes, aminoacylated-tRNA species are used for antibiotic synthesis as well as antibiotic resistance. The direction of coding aminoacylated-tRNA molecules away from translation and into antibiotic resistance and synthesis pathways are discussed in this review.
Collapse
Affiliation(s)
- Jennifer Shepherd
- Department of Microbiology and Center for RNA Biology, Ohio State University, Columbus, OH 43210-1292, USA
| | | |
Collapse
|
19
|
Schmelcher M, Donovan DM, Loessner MJ. Bacteriophage endolysins as novel antimicrobials. Future Microbiol 2013; 7:1147-71. [PMID: 23030422 DOI: 10.2217/fmb.12.97] [Citation(s) in RCA: 474] [Impact Index Per Article: 43.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Endolysins are enzymes used by bacteriophages at the end of their replication cycle to degrade the peptidoglycan of the bacterial host from within, resulting in cell lysis and release of progeny virions. Due to the absence of an outer membrane in the Gram-positive bacterial cell wall, endolysins can access the peptidoglycan and destroy these organisms when applied externally, making them interesting antimicrobial candidates, particularly in light of increasing bacterial drug resistance. This article reviews the modular structure of these enzymes, in which cell wall binding and catalytic functions are separated, as well as their mechanism of action, lytic activity and potential as antimicrobials. It particularly focuses on molecular engineering as a means of optimizing endolysins for specific applications, highlights new developments that may render these proteins active against Gram-negative and intracellular pathogens and summarizes the most recent applications of endolysins in the fields of medicine, food safety, agriculture and biotechnology.
Collapse
Affiliation(s)
- Mathias Schmelcher
- Institute of Food, Nutrition & Health, ETH Zurich, Schmelzbergstrasse 7, 8092 Zurich, Switzerland
| | | | | |
Collapse
|
20
|
Abstract
Peptidoglycan (PG) is the major structural component of the bacterial cell wall. Bacteria have autolytic PG hydrolases that allow the cell to grow and divide. A well-studied group of PG hydrolase enzymes are the bacteriophage endolysins. Endolysins are PG-degrading proteins that allow the phage to escape from the bacterial cell during the phage lytic cycle. The endolysins, when purified and exposed to PG externally, can cause "lysis from without." Numerous publications have described how this phenomenon can be used therapeutically as an effective antimicrobial against certain pathogens. Endolysins have a characteristic modular structure, often with multiple lytic and/or cell wall-binding domains (CBDs). They degrade the PG with glycosidase, amidase, endopeptidase, or lytic transglycosylase activities and have been shown to be synergistic with fellow PG hydrolases or a range of other antimicrobials. Due to the coevolution of phage and host, it is thought they are much less likely to invoke resistance. Endolysin engineering has opened a range of new applications for these proteins from food safety to environmental decontamination to more effective antimicrobials that are believed refractory to resistance development. To put phage endolysin work in a broader context, this chapter includes relevant studies of other well-characterized PG hydrolase antimicrobials.
Collapse
|
21
|
Schmelcher M, Korobova O, Schischkova N, Kiseleva N, Kopylov P, Pryamchuk S, Donovan DM, Abaev I. Staphylococcus haemolyticus prophage ΦSH2 endolysin relies on cysteine, histidine-dependent amidohydrolases/peptidases activity for lysis 'from without'. J Biotechnol 2012; 162:289-98. [PMID: 23026556 DOI: 10.1016/j.jbiotec.2012.09.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 09/07/2012] [Accepted: 09/18/2012] [Indexed: 10/27/2022]
Abstract
Staphylococcus aureus is an important pathogen, with methicillin-resistant (MRSA) and multi-drug resistant strains becoming increasingly prevalent in both human and veterinary clinics. S. aureus causing bovine mastitis yields high annual losses to the dairy industry. Conventional treatment of mastitis by broad range antibiotics is often not successful and may contribute to development of antibiotic resistance. Bacteriophage endolysins present a promising new source of antimicrobials. The endolysin of prophage ΦSH2 of Staphylococcus haemolyticus strain JCSC1435 (ΦSH2 lysin) is a peptidoglycan hydrolase consisting of two catalytic domains (CHAP and amidase) and an SH3b cell wall binding domain. In this work, we demonstrated its lytic activity against live staphylococcal cells and investigated the contribution of each functional module to bacterial lysis by testing a series of deletion constructs in zymograms and turbidity reduction assays. The CHAP domain exhibited three-fold higher activity than the full length protein and optimum activity in physiological saline. This activity was further enhanced by the presence of bivalent calcium ions. The SH3b domain was shown to be required for full activity of the complete ΦSH2 lysin. The full length enzyme and the CHAP domain showed activity against multiple staphylococcal strains, including MRSA strains, mastitis isolates, and CoNS.
Collapse
Affiliation(s)
- Mathias Schmelcher
- ANRI, Agricultural Research Service, US Department of Agriculture, 10300 Baltimore Avenue, Building 230, BARC-EAST, Beltsville, MD 20705, USA
| | | | | | | | | | | | | | | |
Collapse
|
22
|
Chimeric phage lysins act synergistically with lysostaphin to kill mastitis-causing Staphylococcus aureus in murine mammary glands. Appl Environ Microbiol 2012; 78:2297-305. [PMID: 22286996 DOI: 10.1128/aem.07050-11] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococci cause bovine mastitis, with Staphylococcus aureus being responsible for the majority of the mastitis-based losses to the dairy industry (up to $2 billion/annum). Treatment is primarily with antibiotics, which are often ineffective and potentially contribute to resistance development. Bacteriophage endolysins (peptidoglycan hydrolases) present a promising source of alternative antimicrobials. Here we evaluated two fusion proteins consisting of the streptococcal λSA2 endolysin endopeptidase domain fused to staphylococcal cell wall binding domains from either lysostaphin (λSA2-E-Lyso-SH3b) or the staphylococcal phage K endolysin, LysK (λSA2-E-LysK-SH3b). We demonstrate killing of 16 different S. aureus mastitis isolates, including penicillin-resistant strains, by both constructs. At 100 μg/ml in processed cow milk, λSA2-E-Lyso-SH3b and λSA2-E-LysK-SH3b reduced the S. aureus bacterial load by 3 and 1 log units within 3 h, respectively, compared to a buffer control. In contrast to λSA2-E-Lyso-SH3b, however, λSA2-E-LysK-SH3b permitted regrowth of the pathogen after 1 h. In a mouse model of mastitis, infusion of 25 μg of λSA2-E-Lyso-SH3b or λSA2-E-LysK-SH3b into mammary glands reduced S. aureus CFU by 0.63 or 0.81 log units, compared to >2 log for lysostaphin. Both chimeras were synergistic with lysostaphin against S. aureus in plate lysis checkerboard assays. When tested in combination in mice, λSA2-E-LysK-SH3b and lysostaphin (12.5 μg each/gland) caused a 3.36-log decrease in CFU. Furthermore, most protein treatments reduced gland wet weights and intramammary tumor necrosis factor alpha (TNF-α) concentrations, which serve as indicators of inflammation. Overall, our animal model results demonstrate the potential of fusion peptidoglycan hydrolases as antimicrobials for the treatment of S. aureus-induced mastitis.
Collapse
|
23
|
Bamford CV, Francescutti T, Cameron CE, Jenkinson HF, Dymock D. Characterization of a novel family of fibronectin-binding proteins with M23 peptidase domains from Treponema denticola. Mol Oral Microbiol 2011; 25:369-83. [PMID: 21040511 DOI: 10.1111/j.2041-1014.2010.00584.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Interactions with fibronectin are important in the virulence strategies of a range of disease-related bacteria. The periodontitis-associated oral spirochaete Treponema denticola expresses at least two fibronectin-binding proteins, designated Msp (major surface protein) and OppA (oligopeptide-binding protein homologue). To identify other T. denticola outer membrane fibronectin-binding proteins, the amino acid sequence of the Treponema pallidum fibronectin-binding protein Tp0155 was used to survey the T. denticola genome. Seven T. denticola genes encoding orthologous proteins were identified. All but two were expressed in Escherichia coli and purified recombinant proteins bound fibronectin. Using antibodies to the N-terminal region of Tp0155, it was demonstrated that T. denticola TDE2318, with highest homology to Tp0155, was cell surface localized. Like Tp0155, the seven T. denticola proteins contained an M23 peptidase domain and four (TDE2318, TDE2753, TDE1738, TDE1297) contained one or two LysM domains. M23 peptidases can degrade peptidoglycan whereas LysM domains recognize carbohydrate polymers. In addition, TDE1738 may act as a bacteriocin based on homology with other bacterial lysins and the presence of an adjacent gene encoding a putative immunity factor. Collectively, these results suggest that T. denticola expresses fibronectin-binding proteins associated with the cell surface that may also have cell wall modifying or lytic functions.
Collapse
Affiliation(s)
- C V Bamford
- Oral Microbiology Unit, Department of Oral and Dental Science, University of Bristol, Bristol, UK.
| | | | | | | | | |
Collapse
|
24
|
Singh VK, Carlos MR, Singh K. Physiological significance of the peptidoglycan hydrolase, LytM, in Staphylococcus aureus. FEMS Microbiol Lett 2010; 311:167-75. [PMID: 20738399 DOI: 10.1111/j.1574-6968.2010.02087.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Autolysins in bacteria are peptidoglycan hydrolases with roles in growth, turnover and cell lysis. LytM was identified as the only autolysin in a previously reported autolysis-deficient (lyt(-) ) strain of Staphylococcus aureus. Purified LytM has been studied in great detail for its lytic properties and its production is elevated in vancomycin-resistant S. aureus. However, the postulated roles of LytM in S. aureus are largely speculative. Studies utilizing a reporter strain where the lytM promoter was cloned in front of a promoterless lacZ gene and fused in S. aureus strain SH1000 suggest that the expression of lytM is the highest during the early exponential phase. Additionally, lytM expression was downregulated in agr(-) mutants. The expression of lytM was not affected by the presence of cell wall inhibitors in the growth medium. To further determine the significance of LytM in staphylococcal autolysis, the gene encoding LytM was deleted by site-directed mutagenesis. The deletion of lytM, however, did not alter the rate of staphylococcal cell autolysis. Surprisingly, when the lytM mutation was combined with the lyt(-) mutant, the lytic activity band of the lyt(-) strain was still apparent in the lytM:lyt(-) double mutant. Purified full-length His-tagged LytM did not demonstrate any lytic activity against S. aureus cells. Surprisingly, cultures of S. aureus lytM deletion mutant lysed at a significantly faster rate compared with the wild-type S. aureus in the presence of oxacillin. The findings of this study raise questions about LytM as an autolysin and the significance of this protein should thus be investigated beyond its role as an autolysin.
Collapse
Affiliation(s)
- Vineet K Singh
- Microbiology and Immunology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, MO, USA.
| | | | | |
Collapse
|
25
|
Humann J, Lenz LL. Bacterial peptidoglycan degrading enzymes and their impact on host muropeptide detection. J Innate Immun 2010; 1:88-97. [PMID: 19319201 DOI: 10.1159/000181181] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Peptidoglycan (PGN) is a major component of the bacterial cell envelope in both Gram-positive and Gram-negative bacteria. These muropeptides can be produced or modified by the activity of bacterial glycolytic and peptidolytic enzymes referred to as PGN hydrolases and autolysins. Some of these bacterial enzymes are crucial for bacterial pathogenicity and have been shown to modulate muropeptide release and/or host innate immune responses. The ability of muropeptides to modulate host responses is due to the fact that eukaryotes do not produce PGN and have instead evolved numerous strategies to detect intact PGN and PGN fragments (muropeptides). Here we review the structure of PGN and introduce the various bacterial enzymes known to degrade or modify bacterial PGN. Host factors involved in PGN and muropeptide detection are also briefly discussed, as are examples of how specific bacterial pathogens use PGN degradation and modification to subvert host innate immunity.
Collapse
|
26
|
Lysostaphin: A Staphylococcal Bacteriolysin with Potential Clinical Applications. Pharmaceuticals (Basel) 2010; 3:1139-1161. [PMID: 27713293 PMCID: PMC4034026 DOI: 10.3390/ph3041139] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Revised: 04/08/2010] [Accepted: 04/14/2010] [Indexed: 11/16/2022] Open
Abstract
Lysostaphin is an antimicrobial agent belonging to a major class of antimicrobial peptides and proteins known as the bacteriocins. Bacteriocins are bacterial antimicrobial peptides which generally exhibit bactericidal activity against other bacteria. Bacteriocin production is a self-protection mechanism that helps the microorganisms to survive in their natural habitats. Bacteriocins are currently distributed into three main classes. Staphylococcins are bacteriocins produced by staphylococci, which are Gram-positive bacteria of medical and veterinary importance. Lysostaphin is the only class III staphylococcin described so far. It exhibits a high degree of antistaphylococcal bacteriolytic activity, being inactive against bacteria of all other genera. Infections caused by staphylococci continue to be a problem worldwide not only in healthcare environments but also in the community, requiring effective measures for controlling their spread. Since lysostaphin kills human and animal staphylococcal pathogens, it has potential biotechnological applications in the treatment of staphylococcal infections. In vitro and in vivo studies performed with lysostaphin have shown that this staphylococcin has potential to be used, solely or in combination with other antibacterial agents, to prevent or treat bacterial staphylococcal infectious diseases.
Collapse
|
27
|
Zif, the zoocin A immunity factor, is a FemABX-like immunity protein with a novel mode of action. Appl Environ Microbiol 2009; 75:6205-10. [PMID: 19684178 DOI: 10.1128/aem.01011-09] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Producer cell immunity to the streptococcolytic enzyme zoocin A, which is a D-alanyl-L-alanine endopeptidase, is due to Zif, the zoocin A immunity factor. Zif has high degrees of similarity to MurM and MurN (members of the FemABX family of proteins), which are responsible for the addition of amino acids to cross bridges during peptidoglycan synthesis in streptococci. In this study, purified peptidoglycans from strains with and without zif were compared to determine how Zif modifies the peptidoglycan layer to cause resistance to zoocin A. The peptidoglycan from each strain was hydrolyzed using the streptococcolytic phage lysin B30, and the resulting muropeptides were separated by reverse-phase high-pressure liquid chromatography, labeled with 4-sulfophenyl isothiocyanate, and analyzed by tandem mass spectrometry in the negative-ion mode. It was determined that Zif alters the peptidoglycan by increasing the proportion of cross bridges containing three L-alanines instead of two. This modification decreased binding of the recombinant target recognition domain of zoocin A to peptidoglycan. Zif-modified peptidoglycan also was less susceptible to hydrolysis by the recombinant catalytic domain of zoocin A. Thus, Zif is a novel FemABX-like immunity factor because it provides resistance to a bacteriolytic endopeptidase by lengthening the peptidoglycan cross bridge rather than by causing an amino acid substitution.
Collapse
|
28
|
Design of a polypeptide FRET substrate that facilitates study of the antimicrobial protease lysostaphin. Biochem J 2009; 418:615-24. [PMID: 19032148 DOI: 10.1042/bj20081765] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have developed a polypeptide lysostaphin FRET (fluorescence resonance energy transfer) substrate (MV11F) for the endopeptidase activity of lysostaphin. Site-directed mutants of lysostaphin that abolished the killing activity against Staphylococcus aureus also completely inhibited the endopeptidase activity against the MV11 FRET substrate. Lysostaphin-producing staphylococci are resistant to killing by lysostaphin through incorporation of serine residues at positions 3 and 5 of the pentaglycine cross-bridge in their cell walls. The MV11 FRET substrate was engineered to introduce a serine residue at each of four positions of the pentaglycine target site and it was found that only a serine residue at position 3 completely inhibited cleavage. The introduction of random, natural amino acid substitutions at position 3 of the pentaglycine target site demonstrated that only a glycine residue at this position was compatible with lysostaphin cleavage of the MV11 FRET substrate. A second series of polypeptide substrates (decoys) was developed with the GFP (green fluorescent protein) domain of MV11 replaced with that of the DNase domain of colicin E9. Using a competition FRET assay, the lysostaphin endopeptidase was shown to bind to a decoy peptide containing a GGSGG cleavage site. The MV11 substrate provides a valuable system to facilitate structure/function studies of the endopeptidase activity of lysostaphin and its orthologues.
Collapse
|
29
|
Kumar JK. Lysostaphin: an antistaphylococcal agent. Appl Microbiol Biotechnol 2008; 80:555-61. [PMID: 18607587 DOI: 10.1007/s00253-008-1579-y] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Accepted: 06/12/2008] [Indexed: 10/21/2022]
Abstract
Lysostaphin is a zinc metalloenzyme which has a specific lytic action against Staphylococcus aureus. Lysostaphin has activities of three enzymes namely, glycylglycine endopeptidase, endo-beta-N-acetyl glucosamidase and N-acteyl muramyl-L-alanine amidase. Glycylglycine endopeptidase specifically cleaves the glycine-glycine bonds, unique to the interpeptide cross-bridge of the S. aureus cell wall. Due to its unique specificity, lysostaphin could have high potential in the treatment of antibiotic-resistant staphylococcal infections. This review article presents a current understanding of the lysostaphin and its applications in therapeutic agent as a treatment against antibiotic-resistant S. aureus and methicillin-resistant S. aureus (MRSA) infections, either alone or in combination with other antibiotics.
Collapse
Affiliation(s)
- Jaspal K Kumar
- Department of Biochemistry, National University of Singapore, Kent Ridge, Singapore.
| |
Collapse
|
30
|
Mainardi JL, Villet R, Bugg TD, Mayer C, Arthur M. Evolution of peptidoglycan biosynthesis under the selective pressure of antibiotics in Gram-positive bacteria. FEMS Microbiol Rev 2008; 32:386-408. [PMID: 18266857 DOI: 10.1111/j.1574-6976.2007.00097.x] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Acquisition of resistance to the two classes of antibiotics therapeutically used against Gram-positive bacteria, the glycopeptides and the beta-lactams, has revealed an unexpected flexibility in the peptidoglycan assembly pathway. Glycopeptides select for diversification of the fifth position of stem pentapeptides because replacement of D-Ala by D-lactate or D-Ser at this position prevents binding of the drugs to peptidoglycan precursors. The substitution is generally well tolerated by the classical D,D-transpeptidases belonging to the penicillin-binding protein family, except by low-affinity enzymes. Total elimination of the fifth residue by a D,D-carboxypeptidase requires a novel cross-linking enzyme able to process the resulting tetrapeptide stems. This enzyme, an L,D-transpeptidase, confers cross-resistance to beta-lactams and glycopeptides. Diversification of the side chain of the precursors, presumably in response to the selective pressure of peptidoglycan endopeptidases, is controlled by aminoacyl transferases of the Fem family that redirect specific aminoacyl-tRNAs from translation to peptidoglycan synthesis. Diversification of the side chains has been accompanied by a parallel divergent evolution of the substrate specificity of the L,D-transpeptidases, in contrast to the D,D-transpeptidases, which display an unexpected broad specificity. This review focuses on the role of antibiotics in selecting or counter-selecting diversification of the structure of peptidoglycan precursors and their mode of polymerization.
Collapse
Affiliation(s)
- Jean-Luc Mainardi
- INSERM, U872, LRMA, Centre de Recherche des Cordeliers, Paris, France
| | | | | | | | | |
Collapse
|
31
|
Kusuma C, Jadanova A, Chanturiya T, Kokai-Kun JF. Lysostaphin-resistant variants of Staphylococcus aureus demonstrate reduced fitness in vitro and in vivo. Antimicrob Agents Chemother 2006; 51:475-82. [PMID: 17101683 PMCID: PMC1797764 DOI: 10.1128/aac.00786-06] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lysostaphin is under development as a therapy for serious staphylococcal infections. During preclinical development, lysostaphin-resistant Staphylococcus aureus variants have occasionally been reported in vitro and in vivo. The acquisition of resistance to this drug, however, leads to a significant increase in beta-lactam antibiotic susceptibility, rendering methicillin-resistant S. aureus (MRSA) strains functionally methicillin susceptible. In this study, we have demonstrated that the development of lysostaphin resistance by two strains of MRSA also led to a loss of fitness in the variants. Consistent with the mutations found in previously reported lysostaphin-resistant S. aureus variants, these two variants had mutations in their femA genes, resulting in nonfunctional FemA proteins and, thus, monoglycine cross bridges in the peptidoglycan. The diminished fitness of the lysostaphin-resistant variants was reflected by (i) a reduced logarithmic growth rate, with the variants being outcompeted in cocultures by their wild-type parental strains; (ii) increased susceptibility to elevated temperatures; and (iii) at least fivefold less virulence of the lysostaphin-resistant variants than their wild-type strains in a mouse kidney infection model, with the lysostaphin-resistant variants being outcompeted in coinfections with their wild-type parental strains. During a 14-day serial passage without selective pressure, the lysostaphin-resistant variants failed to develop compensatory mutations which restored their fitness. These results suggest that should lysostaphin resistance due to an alteration in the FemA function emerge in S. aureus during therapy with lysostaphin, the resistant variants would be less fit and less virulent, and, in addition, infections with these strains would be easily treatable with beta-lactam antibiotics.
Collapse
Affiliation(s)
- Caroline Kusuma
- Biosynexus Incorporated, 9119 Gaither Rd., Gaithersburg, MD 20877, USA
| | | | | | | |
Collapse
|
32
|
Heath LS, Gargis SR, Smithberg SR, Johnson HP, Heath HE, Leblanc PA, Sloan GL. Plasmid-specified FemABX-like immunity factor in Staphylococcus sciuri DD 4747. FEMS Microbiol Lett 2005; 249:227-31. [PMID: 16006076 DOI: 10.1016/j.femsle.2005.06.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2005] [Accepted: 06/09/2005] [Indexed: 11/20/2022] Open
Abstract
A plasmid from Staphylococcus sciuri DD 4747 had three open reading frames: a replication gene, an N-acetylmuramyl-l-alanine amidase-like gene, and a gene similar to the lysostaphin endopeptidase resistance gene (epr/lif). The epr-like gene was introduced into S. aureus RN4220; the recombinant strain was more resistant to lysostaphin endopeptidase and its cell wall peptidoglycan contained more serines and fewer glycines than the parental strain with the shuttle vector alone. Based on both its function and its similarity to femAB, this gene is a member of the femABX-like immunity gene family. Furthermore, this is the first example of a femABX-like immunity gene that is not linked to the gene for the bacteriolytic enzyme against which it specifies immunity.
Collapse
Affiliation(s)
- Lucie S Heath
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487-0334, USA
| | | | | | | | | | | | | |
Collapse
|
33
|
Lu JZ, Fujiwara T, Komatsuzawa H, Sugai M, Sakon J. Cell wall-targeting domain of glycylglycine endopeptidase distinguishes among peptidoglycan cross-bridges. J Biol Chem 2005; 281:549-58. [PMID: 16257954 DOI: 10.1074/jbc.m509691200] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ALE-1, a homologue of lysostaphin, is a peptidoglycan hydrolase that specifically lyses Staphylococcus aureus cell walls by cleaving the pentaglycine linkage between the peptidoglycan chains. Binding of ALE-1 to S. aureus cells through its C-terminal 92 residues, known as the targeting domain, is functionally important for staphylolytic activity. The ALE-1-targeting domain belongs to the SH3b domain family, the prokaryotic counterpart of the eukaryotic SH3 domains. The 1.75 angstroms crystal structure of the targeting domain shows an all-beta fold similar to typical SH3s but with unique features. The structure reveals patches of conserved residues among orthologous targeting domains, forming surface regions that can potentially interact with some common features of the Gram-positive cell wall. ALE-1-targeting domain binding studies employing various bacterial peptidoglycans demonstrate that the length of the interpeptide bridge, as well as the amino acid composition of the peptide, confers the maximum binding of the targeting domain to the staphylococcal peptidoglycan. Truncation of the highly conserved first 9 N-terminal residues results in loss of specificity to S. aureus cell wall-targeting, suggesting that these residues confer specificity to S. aureus cell wall.
Collapse
Affiliation(s)
- Jeff Zhiqiang Lu
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | | | | | | | | |
Collapse
|
34
|
Kajimura J, Fujiwara T, Yamada S, Suzawa Y, Nishida T, Oyamada Y, Hayashi I, Yamagishi JI, Komatsuzawa H, Sugai M. Identification and molecular characterization of anN-acetylmuramyl-l-alanine amidase Sle1 involved in cell separation ofStaphylococcus aureus. Mol Microbiol 2005; 58:1087-101. [PMID: 16262792 DOI: 10.1111/j.1365-2958.2005.04881.x] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We purified a peptidoglycan hydrolase involved in cell separation from a Staphylococcus aureus atl null mutant and identified its gene. Characterization of the gene product shows a 32 kDa N-acetylmuramyl-L-alanine amidase that we designated Sle1. Analysis of peptidoglycan digests showed Sle1 preferentially cleaved N-acetylmuramyl-L-Ala bonds in dimeric cross-bridges that interlink the two murein strands in the peptidoglycan. An insertion mutation of sle1 impaired cell separation and induced S. aureus to form clusters suggesting Sle1 is involved in cell separation of S. aureus. The Sle1 mutant revealed a significant decrease in pathogenesis using an acute infection mouse model. Atl is the major autolysin of S. aureus, which has been implicated in cell separation of S. aureus. Generation of an atl/sle1 double mutant revealed that the mutant cell separation was heavily impaired suggesting that S. aureus uses two peptidoglycan hydrolases, Atl and Sle1, for cell separation. Unlike Atl, Sle1 is not directly involved in autolysis of S. aureus.
Collapse
Affiliation(s)
- Junko Kajimura
- Department of Bacteriology, Hiroshima University Graduate School of Biomedical Sciences, 1-2-3 Kasumi Hiroshima City, Hiroshima 734-8553, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Wootton M, Bennett PM, MacGowan AP, Walsh TR. Reduced expression of the atl autolysin gene and susceptibility to autolysis in clinical heterogeneous glycopeptide-intermediate Staphylococcus aureus (hGISA) and GISA strains. J Antimicrob Chemother 2005; 56:944-7. [PMID: 16157619 DOI: 10.1093/jac/dki289] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES To assess a link between resistance to Triton X-100 induced autolysis (TIA) and lowered atl expression in a collection of clinical glycopeptide-intermediate Staphylococcus aureus (GISA) and heterogeneous GISA (hGISA). METHODS Nine clinical GISA, 11 hGISA and 11 glycopeptide-susceptible S. aureus (GSSA), including three pairs of related isolates, were analysed using TIA assays. Lysostaphin MICs were determined by a broth microdilution technique and reverse transcriptase PCR was used to compare atl expression levels in all isolates. RESULTS Eight of nine clinical GISA and six of 11 hGISA exhibited lower susceptibility to TIA and higher MICs of lysostaphin than GSSA. Eight of nine GISA and all hGISA strains had lowered atl expression levels compared with GSSA. CONCLUSIONS The majority of GISA and hGISA isolates exhibited lowered susceptibility to TIA and lysostaphin and reduced atl expression when compared with GSSA isolates. These factors could contribute to, or predispose to the development of, a thickened cell wall and glycopeptide-intermediate resistance.
Collapse
Affiliation(s)
- Mandy Wootton
- Bristol Centre for Antimicrobial Research and Evaluation, Department of Cellular and Molecular Medicine, Medical Sciences, University of Bristol, Bristol BS1 8TD, UK.
| | | | | | | |
Collapse
|
36
|
Shaw LN, Golonka E, Szmyd G, Foster SJ, Travis J, Potempa J. Cytoplasmic control of premature activation of a secreted protease zymogen: deletion of staphostatin B (SspC) in Staphylococcus aureus 8325-4 yields a profound pleiotropic phenotype. J Bacteriol 2005; 187:1751-62. [PMID: 15716447 PMCID: PMC1064019 DOI: 10.1128/jb.187.5.1751-1762.2005] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cytoplasmic protein SspC of Staphylococcus aureus, referred to as staphostatin B, is a very specific, tightly binding inhibitor of the secreted protease staphopain B (SspB). SspC is hypothesized to protect intracellular proteins against proteolytic damage by prematurely folded and activated staphopain B (M. Rzychon, A. Sabat, K. Kosowska, J. Potempa, and A. Dubin, Mol. Microbiol. 49:1051-1066, 2003). Here we provide evidence that elimination of intracellular staphopain B activity is indeed the function of SspC. An isogenic sspC mutant of S. aureus 8325-4 exhibits a wide range of striking pleiotropic alterations in phenotype, which distinguish it from the parent. These changes include a defect in growth, a less structured peptidoglycan layer within the cell envelope, severely decreased autolytic activity, resistance to lysis by S. aureus phages, extensively diminished sensitivity to lysis by lysostaphin, the ability to form a biofilm, and a total lack of extracellular proteins secreted into the growth media. The same phenotype was also engineered by introduction of sspB into an 8325-4 sspBC mutant. In contrast, sspC inactivation in the SH1000 strain did not yield any significant changes in the mutant phenotype, apparently due to strongly reduced expression of sspB in the sigma B-positive background. The exact pathway by which these diverse aberrations are exerted in 8325-4 is unknown, but it is apparent that a very small amount of staphopain B (less than 20 ng per 200 microg of cell proteins) is sufficient to bring about these widespread changes. It is proposed that the effects observed are modulated through the proteolytic degradation of several cytoplasmic proteins within cells lacking the inhibitor. Seemingly, some of these proteins may play a role in protein secretion; hence, their proteolytic inactivation by SspB has pleiotropic effects on the SspC-deficient mutant.
Collapse
Affiliation(s)
- Lindsey N Shaw
- Department of Biochemistry and Molecular Biology, University of Georgia, Life Sciences Bldg., Athens, GA 30602, USA
| | | | | | | | | | | |
Collapse
|
37
|
Schneider T, Senn MM, Berger-Bächi B, Tossi A, Sahl HG, Wiedemann I. In vitro assembly of a complete, pentaglycine interpeptide bridge containing cell wall precursor (lipid II-Gly5) of Staphylococcus aureus. Mol Microbiol 2005; 53:675-85. [PMID: 15228543 DOI: 10.1111/j.1365-2958.2004.04149.x] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Staphylococcus aureus peptidoglycan is cross-linked via a characteristic pentaglycine interpeptide bridge. Genetic analysis had identified three peptidyltransferases, FemA, FemB and FemX, to catalyse the formation of the interpeptide bridge, using glycyl t-RNA as Gly donor. To analyse the pentaglycine bridge formation in vitro, we purified the potential substrates for FemA, FemB and FemX, UDP-MurNAc-pentapeptide, lipid I and lipid II and the staphylococcal t-RNA pool, as well as His-tagged Gly-tRNA-synthetase and His-tagged FemA, FemB and FemX. We found that FemX used lipid II exclusively as acceptor for the first Gly residue. Addition of Gly 2,3 and of Gly 4,5 was catalysed by FemA and FemB, respectively, and both enzymes were specific for lipid II-Gly1 and lipid II-Gly3 as acceptors. None of the FemABX enzymes required the presence of one or two of the other Fem proteins for activity; rather, bridge formation was delayed in the in vitro system when all three enzymes were present. The in vitro assembly system described here will enable detailed analysis of late, membrane-associated steps of S. aureus peptidoglycan biosynthesis.
Collapse
Affiliation(s)
- Tanja Schneider
- Institut für Medizinische Mikrobiologie und Immunologie der Universität Bonn, D-53105 Bonn, Germany
| | | | | | | | | | | |
Collapse
|
38
|
Rohrer S, Berger-Bächi B. FemABX peptidyl transferases: a link between branched-chain cell wall peptide formation and beta-lactam resistance in gram-positive cocci. Antimicrob Agents Chemother 2003; 47:837-46. [PMID: 12604510 PMCID: PMC149326 DOI: 10.1128/aac.47.3.837-846.2003] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- S Rohrer
- Institute of Medical Microbiology, University of Zürich, Switzerland
| | | |
Collapse
|
39
|
Takahashi J, Komatsuzawa H, Yamada S, Nishida T, Labischinski H, Fujiwara T, Ohara M, Yamagishi JI, Sugai M. Molecular characterization of an atl null mutant of Staphylococcus aureus. Microbiol Immunol 2003; 46:601-12. [PMID: 12437027 DOI: 10.1111/j.1348-0421.2002.tb02741.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
atl is a gene encoding a bifunctional peptidoglycan hydrolase of Staphylococcus aureus. The gene product of atl is a 138 kDa protein that has an amidase domain and a glucosaminidase domain, and undergoes processing to generate two major peptidoglycan hydrolases, a 51 kDa glucosaminidase and a 62 kDa amidase in culture supernatant. An atl null mutant was isolated by allelic replacement and characterized. The mutant grew in clusters and sedimented when grown in broth culture. Analysis of peptidoglycan prepared from the wild type and the mutant revealed that there were no differences in muropeptide composition or in glycan chain length distribution. On the other hand, the atl mutation resulted in pleiotropic effects on cell surface nature. The mutant cells showed complete inhibition of metabolic turnover of cell wall peptidoglycan and revealed a rough outer cell wall surface. The mutation also decreased the amount of protein non-covalently bound to the cell surface and altered the protein profile, but did not affect proteins covalently associated with the cell wall. Lysis of growing cells treated with otherwise lytic concentration of penicillin G was completely inhibited in the mutant, but that of non-growing cells was not affected by the mutation. The atl mutation did not significantly affect the ability of S. aureus to provoke an acute infection when inoculated intraperitoneally in a mouse sepsis model. These results further support the supposition that atl gene products are involved in cell separation, cell wall turnover and penicillin-induced lysis of the cells.
Collapse
Affiliation(s)
- Junko Takahashi
- Department of Bacteriology, Hiroshima University Graduate School of Biomedical Sciences, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Kerr DE, Wellnitz O. Mammary expression of new genes to combat mastitis. J Anim Sci 2003; 81 Suppl 3:38-47. [PMID: 15000405 PMCID: PMC7110379 DOI: 10.2527/2003.81suppl_338x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2002] [Accepted: 12/18/2002] [Indexed: 11/23/2022] Open
Abstract
Continual advances in the ability to produce transgenic animals make it likely that such animals will become important components of animal agriculture. The full benefit of the technology, and justification of its initial cost outlay, will be dependent on the establishment within these animals of new traits not easily achievable by other means. Potential applications include enhanced nutrient digestibility with reduced fecal losses, significantly altered milk composition with superior nutritional properties, and enhanced disease resistance. Our goal is to enhance mastitis resistance of dairy cows by enabling the cells of the mammary gland to secrete additional antibacterial proteins. Proof of concept has been obtained through experimentation with a transgenic mouse model. Three lines of mice were developed that produce varying levels of lysostaphin in their milk. This protein has potent anti-staphylococcal activity and its secretion into milk confers substantial resistance to infection caused by intramammary challenge with Staphylococcus aureus, a major mastitis pathogen. Additional antibacterial proteins are being sought that will complement lysostaphin. A potential benefit of transgenic application of antibacterial proteins is the concomitant sparing in the agricultural use of antibiotics currently used as human therapeutics. Antibacterial proteins, such as lysostaphin, are not typically used as injectable or oral therapeutics because of immune-mediated or digestive destruction of their activity. In contrast, the immune system of transgenic animals will not consider the transgenic protein as being foreign. In addition we are exploring the potential of involution or mastitis responsive promoter elements for use in subsequent transgenic experiments designed to restrict lysostaphin production to these important time points. It is anticipated that genomics will play a role in unveiling candidate genes whose promoter elements will enable desired temporal expression patterns. The transgenic approach to insertion of new genetic material into agriculturally important animals is feasible but requires extensive prior evaluation of the transgene and transgene product in model systems.
Collapse
Affiliation(s)
- D E Kerr
- Department of Animal Science, University of Vermont, Burlington 05405, USA.
| | | |
Collapse
|
41
|
Reinscheid DJ, Stößer C, Ehlert K, Jack RW, Möller K, Eikmanns BJ, Chhatwal GS. Influence of proteins Bsp and FemH on cell shape and peptidoglycan composition in group B streptococcus. MICROBIOLOGY (READING, ENGLAND) 2002; 148:3245-3254. [PMID: 12368458 DOI: 10.1099/00221287-148-10-3245] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Group B streptococcus (GBS) is surrounded by a capsule. However, little is known about peptidoglycan metabolism in these bacteria. In the present study, a 65 kDa protein was isolated from the culture supernatant of GBS and N-terminally sequenced, permitting isolation of the corresponding gene, termed bsp. The bsp gene was located close to another gene, designated femH, and reverse transcription-PCR revealed a bicistronic transcriptional organization for both genes. The Bsp protein was detected in the culture supernatant from 31 tested clinical isolates of GBS, suggesting a wide distribution of Bsp in these bacteria. Overexpression of bsp resulted in lens-shaped GBS cells, indicating a role for bsp in controlling cell morphology. Insertional disruption of femH resulted in a reduction of the L-alanine content of the peptidoglycan, suggesting that femH is involved in the incorporation of L-alanine residues in the interpeptide chain of the peptidoglycan of GBS.
Collapse
Affiliation(s)
- Dieter J Reinscheid
- Department of Microbiology, GBF-National Research Centre for Biotechnology,D-38124 Braunschweig, Germany2
- Department of Microbiology and Biotechnology, University of Ulm, D-89069 Ulm, Germany1
| | - Claudia Stößer
- Department of Microbiology and Biotechnology, University of Ulm, D-89069 Ulm, Germany1
| | - Kerstin Ehlert
- Bayer AG, PH Research Antiinfectives I, D-42096 Wuppertal, Germany3
| | - Ralph W Jack
- Institute for Organic Chemistry, University of Tübingen, D-72070 Tübingen, Germany4
| | - Kerstin Möller
- Department of Microbiology, GBF-National Research Centre for Biotechnology,D-38124 Braunschweig, Germany2
| | - Bernhard J Eikmanns
- Department of Microbiology and Biotechnology, University of Ulm, D-89069 Ulm, Germany1
| | - Gursharan S Chhatwal
- Department of Microbiology, GBF-National Research Centre for Biotechnology,D-38124 Braunschweig, Germany2
| |
Collapse
|
42
|
Kiri N, Archer G, Climo MW. Combinations of lysostaphin with beta-lactams are synergistic against oxacillin-resistant Staphylococcus epidermidis. Antimicrob Agents Chemother 2002; 46:2017-20. [PMID: 12019130 PMCID: PMC127219 DOI: 10.1128/aac.46.6.2017-2020.2002] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2001] [Revised: 11/19/2001] [Accepted: 02/10/2002] [Indexed: 11/20/2022] Open
Abstract
Oxacillin-resistant Staphylococcus aureus is rapidly killed by the endopeptidase lysostaphin, and the addition of beta-lactam antibiotics provides synergistic killing. We investigated the possibility that beta-lactams given in combination with lysostaphin would improve the activity of lysostaphin against oxacillin-resistant Staphylococcus epidermidis (ORSE), which is normally less susceptible to lysostaphin. Checkerboard synergy testing was performed for lysostaphin given in combination with oxacillin against 10 ORSE isolates for which the lysostaphin MICs were > o r= 8 microg/ml. The fractional inhibitory concentration index ranged from 0.0234 to 0.2656, indicating synergy, which was confirmed in growth curve experiments. In the rabbit model of experimental aortic valve endocarditis using an ORSE strain, the combination of lysostaphin and nafcillin was as effective as vancomycin alone and significantly better than lysostaphin or nafcillin alone. We conclude that beta-lactam antibiotics given in combination with lysostaphin are synergistic against many strains of ORSE.
Collapse
Affiliation(s)
- Nandini Kiri
- Department of Medicine, Virginia Commonwealth University Health Science System, Richmond, Virginia 23249, USA
| | | | | |
Collapse
|
43
|
Beukes M, Hastings JW. Self-protection against cell wall hydrolysis in Streptococcus milleri NMSCC 061 and analysis of the millericin B operon. Appl Environ Microbiol 2001; 67:3888-96. [PMID: 11525982 PMCID: PMC93106 DOI: 10.1128/aem.67.9.3888-3896.2001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus milleri NMSCC 061 produces an endopeptidase, millericin B, which hydrolyzes the peptide moiety of susceptible cell wall peptidoglycan. The nucleotide sequence of a 4.9-kb chromosomal region showed three open reading frames (ORFs) and a putative tRNA(Leu) sequence. The three ORFs encode a millericin B preprotein (MilB), a putative immunity protein (MilF), and a putative transporter protein (MilT). The milB gene encodes a 277-amino-acid preprotein with an 18-amino-acid signal peptide with a consensus IIGG cleavage motif. The predicted protein encoded by milT is homologous to ABC (ATP-binding cassette) transporters of several bacteriocin systems and to proteins implicated in the signal-sequence-independent export of Escherichia coli hemolysin A. These similarities strongly suggest that the milT gene product is involved in the translocation of millericin B. The gene milF encodes a protein of 302 amino acids that shows similarities to the FemA and FemB proteins of Staphylococcus aureus, which are involved in the addition of glycine to a pentapeptide peptidoglycan precursor. Comparisons of the cell wall mucopeptide of S. milleri NMSCC 061(resistant to lysis by millericin B) and S. milleri NMSCC 051(sensitive) showed a single amino acid difference. Serial growth of S. milleri NMSCC 051 in a cell wall minimal medium containing an increased concentration of leucine resulted in the in vivo substitution of leucine for threonine in the mucopeptide of the cell wall. A cell wall variant of S. milleri NMSCC 051 (sensitive) that contained an amino acid substitution (leucine for threonine) within its peptidoglycan cross bridge showed partial susceptibility to millericin B. The putative tRNA(Leu) sequence located upstream of milB may be a cell wall-specific tRNA and could together with the milF protein, play a potential role in the addition of leucine to the pentapeptide peptidoglycan precursor and thereby, contributing to self-protection to millericin B in the producer strain.
Collapse
Affiliation(s)
- M Beukes
- School of Molecular and Cellular Biosciences, University of Natal, Pietermaritzburg, Scottsville 3209, South Africa
| | | |
Collapse
|
44
|
Netz DJ, Sahl HG, Marcelino R, dos Santos Nascimento J, de Oliveira SS, Soares MB, do Carmo de Freire Bastos M, Marcolino R. Molecular characterisation of aureocin A70, a multi-peptide bacteriocin isolated from Staphylococcus aureus. J Mol Biol 2001; 311:939-49. [PMID: 11531330 DOI: 10.1006/jmbi.2001.4885] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Staphylococcus aureus A70 produces a heat-stable bacteriocin designated aureocin A70. Aureocin A70 is encoded within a mobilisable 8 kb plasmid, pRJ6, and is active against Listeria monocytogenes. Experiments of transposition mutagenesis and gene cloning had shown that aureocin A70 production and immunity were associated with the HindIII-A and B fragments of pRJ6. Therefore, a 6332 bp region of the plasmid, encompassing both these fragments, was sequenced using a concatenation DNA sequencing procedure. DNA sequence and genetic analyses revealed the presence of three transcriptional units that appear to be involved in bacteriocin activity. The first transcriptional unit contains a single gene, aurT, which encodes a protein that resembles an ATP-dependent transporter, similar to those involved in lantibiotic export. AurT is required for aureocin A70 production and it appears to be essential for mobilisation of pRJ6. The second putative operon contains two open reading frames (ORFs); the first gene, orfA, is predicted to encode a protein similar to small repressor proteins found in some Archaea, whose function remains to be elucidated. The second gene, orfB, codes for an 138 amino acid residue protein which shares a number of characteristics (high pI and hydrophobicity profile) with proteins associated with immunity, needed for self-protection against bacteriocin. Four other genes are present in the third operon, aurABCD. aurABCD encode four related peptides that are small (30-31 amino acid residues), strongly cationic (pI of 9.85 to 10.04) and highly hydrophobic. Theses peptides also have a high content of small amino acid residues like glycine and alanine, and no cysteine residue. Tn917-lac insertional mutations, which affected aureocin A70 activity, reside within operon aurABCD. Analysis of purified bacteriocin preparations by mass spectrometry demonstrated that all four peptides encoded by aurABCD operon are produced, expressed and excreted without post-translational modifications. Thus, aureocin A70 is a multi-peptide non-lantibiotic bacteriocin, which is transported without processing.
Collapse
Affiliation(s)
- D J Netz
- Departamento de Microbiologia Geral, Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Brazil
| | | | | | | | | | | | | | | |
Collapse
|
45
|
Filipe SR, Pinho MG, Tomasz A. Characterization of the murMN operon involved in the synthesis of branched peptidoglycan peptides in Streptococcus pneumoniae. J Biol Chem 2000; 275:27768-74. [PMID: 10869361 DOI: 10.1074/jbc.m004675200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The murMN operon, recently identified in the genome of Streptococcus pneumoniae, encodes for enzymes involved in the synthesis of branched structured muropeptides in the pneumococcal peptidoglycan; inactivation of murMN causes production of a peptidoglycan composed exclusively of linear muropeptides and a virtually complete loss of resistance in penicillin-resistant strains (Filipe, S. R., and Tomasz, A. (2000) Proc. Natl. Acad. Sci. U. S. A. 97, 4891-4896). The experiments described in this paper follow up these observations. Primer extension analysis was used to identify the putative promoter region of the murMN operon in penicillin-susceptible and -resistant strains. Selective inactivation of the murN gene in the penicillin-resistant strain Pen6 caused production of an unusual peptidoglycan that contained only single amino acid residues in the muropeptide branches, indicating that the product of murN was involved with the addition of the second amino acid and the product of murM was involved with the addition of the first amino acid (alanine or serine) to the peptidoglycan cross-bridge. Allelic replacement of the mosaic murM gene of strain Pen6 with murM of the penicillin-susceptible laboratory strain caused enrichment of the peptidoglycan in linear muropeptides. The findings suggest that the genetic determinant primarily controlling the synthesis of branched muropeptides in the pneumococcal peptidoglycan is murM.
Collapse
Affiliation(s)
- S R Filipe
- Laboratory of Microbiology, The Rockefeller University, New York, New York 10021, USA
| | | | | |
Collapse
|
46
|
Ochiai T. Staphylococcus aureus produces autolysin-susceptible cell walls during growth in a high-NaCl and low-Ca2+ concentration medium. Microbiol Immunol 2000; 44:97-104. [PMID: 10803496 DOI: 10.1111/j.1348-0421.2000.tb01252.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The growth of Staphylococcus aureus 209P becomes unusually sensitive to a high-NaCl concentration by decreasing the Ca2+ concentration in growth media, and cells either autolyze or transform into protoplast-like forms when grown standing in high-NaCl and low-Ca2+ concentration media below 37 C (Ochiai, T., Microbiol. Immunol. 43 (7): 705-709, 1999). To assess the role of Ca2+ in the salt tolerance of this organism, cells grown in the presence of different concentrations of Ca2+ were treated with boiling SDS, and their susceptibilities to crude autolysin (3 M LiCl extract of S. aureus 209P cells) were evaluated by turbidimetric assay and zymographic analysis. Susceptibilities of SDS-treated cells (SDS-cells) to crude autolysin were significantly influenced by Ca2+ concentration in the culture, and SDS-cells prepared from cultures grown in high-NaCl and high-Ca2+ concentration media exhibited marked resistance to crude autolysin when the assay system contained a high concentration of NaCl. On the contrary, SDS-cells prepared from cultures grown in high-NaCl and low-Ca2+ concentration media were rather susceptible to crude autolysin under the same assay conditions. A zymographic analysis revealed that the constitution of cell-associated autolysins was not influenced by the concentration of exogenous Ca2+. These results suggested that at least part of the mechanism of salt-induced autolysis in S. aureus 209P might be related to the synthesis of an autolysin susceptible cell wall.
Collapse
Affiliation(s)
- T Ochiai
- Faculty of Pharmaceutical Science, Hokuriku University, Kanazawa, Ishikawa, Japan
| |
Collapse
|
47
|
Weber B, Ehlert K, Diehl A, Reichmann P, Labischinski H, Hakenbeck R. The fib locus in Streptococcus pneumoniae is required for peptidoglycan crosslinking and PBP-mediated beta-lactam resistance. FEMS Microbiol Lett 2000; 188:81-5. [PMID: 10867238 DOI: 10.1111/j.1574-6968.2000.tb09172.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Penicillin resistance in pneumococci is mediated by modified penicillin-binding proteins (PBPs) that have decreased affinity to beta-lactams. In high-level penicillin-resistant transformants of the laboratory strain Streptococcus pneumoniae R6 containing various combinations of low-affinity PBPs, disruption of the fib locus results in a collapse of PBP-mediated resistance. In addition, crosslinked muropeptides are highly reduced. The fib operon consists of two genes, fibA and fibB, homologous to Staphylococcus aureus femA/B which are also required for expression of methicillin resistance in this organism. FibA and FibB belong to a family of proteins of Gram-positive bacteria involved in the formation of interpeptide bridges, thus representing interesting new targets for antimicrobial compounds for this group of pathogens.
Collapse
Affiliation(s)
- B Weber
- Univerität Kaiserslautern, Abteilung Mikrobiologie, Paul-Erlich Strasse, Kaiserslautern, Germany
| | | | | | | | | | | |
Collapse
|
48
|
Ehlert K, Tschierske M, Mori C, Schröder W, Berger-Bächi B. Site-specific serine incorporation by Lif and Epr into positions 3 and 5 of the Staphylococcal peptidoglycan interpeptide bridge. J Bacteriol 2000; 182:2635-8. [PMID: 10762270 PMCID: PMC111332 DOI: 10.1128/jb.182.9.2635-2638.2000] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The FemAB-like factors Lif and Epr confer resistance to glycylglycine endopeptidases lysostaphin and Ale-1, respectively, by incorporating serine residues into the staphylococcal peptidoglycan interpeptide bridges specifically at positions 3 and 5. This required the presence of FemA and/or FemB, in contrast to earlier postulations.
Collapse
Affiliation(s)
- K Ehlert
- Bayer AG, PH Research Antiinfectives I, D-42096 Wuppertal, Germany
| | | | | | | | | |
Collapse
|
49
|
Rohrer S, Ehlert K, Tschierske M, Labischinski H, Berger-Bächi B. The essential Staphylococcus aureus gene fmhB is involved in the first step of peptidoglycan pentaglycine interpeptide formation. Proc Natl Acad Sci U S A 1999; 96:9351-6. [PMID: 10430946 PMCID: PMC17786 DOI: 10.1073/pnas.96.16.9351] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The factor catalyzing the first step in the synthesis of the characteristic pentaglycine interpeptide in Staphylococcus aureus peptidoglycan was found to be encoded by the essential gene fmhB. We have analyzed murein composition and structure synthesized when fmhB expression is reduced. The endogenous fmhB promoter was substituted with the xylose regulon from Staphylococcus xylosus, which allowed glucose-controlled repression of fmhB transcription. Repression of fmhB reduced growth and triggered a drastic accumulation of uncrosslinked, unmodified muropeptide monomer precursors at the expense of the oligomeric fraction, leading to a substantial decrease in overall peptidoglycan crosslinking. The composition of the predominant muropeptide was confirmed by MS to be N-acetylglucosamine-(beta-1,4)-N-acetylmuramic acid(-L-Ala-D-iGln-L-Lys-D-Ala-D-Ala), proving that FmhB is involved in the attachment of the first glycine to the pentaglycine interpeptide. This interpeptide plays an important role in crosslinking and stability of the S. aureus cell wall, acts as an anchor for cell wall-associated proteins, determinants of pathogenicity, and is essential for the expression of methicillin resistance. Any shortening of the pentaglycine side chain reduces or even abolishes methicillin resistance, as occurred with fmhB repression. Because of its key role FmhB is a potential target for novel antibacterial agents that could control the threat of emerging multiresistant S. aureus.
Collapse
Affiliation(s)
- S Rohrer
- Institute of Medical Microbiology, University of Zürich, Gloriastr. 32, Postfach, CH-8028 Zürich, Switzerland
| | | | | | | | | |
Collapse
|
50
|
Navarre WW, Schneewind O. Surface proteins of gram-positive bacteria and mechanisms of their targeting to the cell wall envelope. Microbiol Mol Biol Rev 1999; 63:174-229. [PMID: 10066836 PMCID: PMC98962 DOI: 10.1128/mmbr.63.1.174-229.1999] [Citation(s) in RCA: 925] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cell wall envelope of gram-positive bacteria is a macromolecular, exoskeletal organelle that is assembled and turned over at designated sites. The cell wall also functions as a surface organelle that allows gram-positive pathogens to interact with their environment, in particular the tissues of the infected host. All of these functions require that surface proteins and enzymes be properly targeted to the cell wall envelope. Two basic mechanisms, cell wall sorting and targeting, have been identified. Cell well sorting is the covalent attachment of surface proteins to the peptidoglycan via a C-terminal sorting signal that contains a consensus LPXTG sequence. More than 100 proteins that possess cell wall-sorting signals, including the M proteins of Streptococcus pyogenes, protein A of Staphylococcus aureus, and several internalins of Listeria monocytogenes, have been identified. Cell wall targeting involves the noncovalent attachment of proteins to the cell surface via specialized binding domains. Several of these wall-binding domains appear to interact with secondary wall polymers that are associated with the peptidoglycan, for example teichoic acids and polysaccharides. Proteins that are targeted to the cell surface include muralytic enzymes such as autolysins, lysostaphin, and phage lytic enzymes. Other examples for targeted proteins are the surface S-layer proteins of bacilli and clostridia, as well as virulence factors required for the pathogenesis of L. monocytogenes (internalin B) and Streptococcus pneumoniae (PspA) infections. In this review we describe the mechanisms for both sorting and targeting of proteins to the envelope of gram-positive bacteria and review the functions of known surface proteins.
Collapse
Affiliation(s)
- W W Navarre
- Department of Microbiology & Immunology, UCLA School of Medicine, Los Angeles, California 90095, USA
| | | |
Collapse
|