51
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Chen X, Wong CH, Ma C. Targeting the Bacterial Transglycosylase: Antibiotic Development from a Structural Perspective. ACS Infect Dis 2019; 5:1493-1504. [PMID: 31283163 DOI: 10.1021/acsinfecdis.9b00118] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
One of the major threats to human life nowadays is widespread antibiotic resistance. Antibiotics are used to treat bacterial infections by targeting their essential pathways, such as the biosynthesis of bacterial cell walls. Bacterial transglycosylase, particularly glycosyltransferase family 51 (GT51), is one critical player in the cell wall biosynthesis and has long been known as a promising yet challenging target for antibiotic development. Here, we review the structural studies of this protein and summarize recent progress in developing its specific inhibitors, including synthetic substrate analogs and novel compounds identified from high-throughput screens. A detailed analysis of the protein-ligand interface has also provided us with valuable insights into the future antibiotic development against the bacterial transglycosylase.
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Affiliation(s)
- Xiaorui Chen
- Genomics Research Center, Academia Sinica, No. 128, Section 2, Academia Road, Nangang District, Taipei 115, Taiwan
| | - Chi-Huey Wong
- Genomics Research Center, Academia Sinica, No. 128, Section 2, Academia Road, Nangang District, Taipei 115, Taiwan
| | - Che Ma
- Genomics Research Center, Academia Sinica, No. 128, Section 2, Academia Road, Nangang District, Taipei 115, Taiwan
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52
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Unsleber S, Wohlleben W, Stegmann E. Diversity of peptidoglycan structure—Modifications and their physiological role in resistance in antibiotic producers. Int J Med Microbiol 2019; 309:151332. [DOI: 10.1016/j.ijmm.2019.151332] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 07/12/2019] [Accepted: 07/15/2019] [Indexed: 11/29/2022] Open
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53
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Pichoff S, Du S, Lutkenhaus J. Roles of FtsEX in cell division. Res Microbiol 2019; 170:374-380. [PMID: 31376483 DOI: 10.1016/j.resmic.2019.07.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 07/09/2019] [Accepted: 07/16/2019] [Indexed: 02/04/2023]
Abstract
FtsEX is a member of a small subclass of ABC transporters that uses mechano-transmission to perform work in the periplasm. FtsEX controls periplasmic peptidoglycan (PG) hydrolase activities in many Gram negative and positive organisms to ensure the safe separation of daughter cells during division. In these organisms FtsEX localizes to the Z ring and uses its ATPase activity to regulate its periplasmic effectors. In Escherichia coli, FtsEX also participates in building the divisome and coordinates PG synthesis with PG hydrolysis. This review discusses studies that are beginning to elucidate the mechanisms of FtsEX's various roles in cell division.
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Affiliation(s)
- Sebastien Pichoff
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, 66160, USA
| | - Shishen Du
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, 66160, USA
| | - Joe Lutkenhaus
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, 66160, USA.
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54
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Abstract
BolA family proteins are conserved in Gram-negative bacteria and many eukaryotes. While diverse cellular phenotypes have been linked to this protein family, the molecular pathways through which these proteins mediate their effects are not well described. Here, we investigated the roles of BolA family proteins in Vibrio cholerae, the cholera pathogen. Like Escherichia coli, V. cholerae encodes two BolA proteins, BolA and IbaG. However, in marked contrast to E. coli, where bolA is linked to cell shape and ibaG is not, in V. cholerae, bolA mutants lack morphological defects, whereas ibaG proved critical for the generation and/or maintenance of the pathogen's morphology. Notably, the bizarre-shaped, multipolar, elongated, and wide cells that predominated in exponential-phase ΔibaG V. cholerae cultures were not observed in stationary-phase cultures. The V. cholerae ΔibaG mutant exhibited increased sensitivity to cell envelope stressors, including cell wall-acting antibiotics and bile, and was defective in intestinal colonization. ΔibaG V. cholerae had reduced peptidoglycan and lipid II and altered outer membrane lipids, likely contributing to the mutant's morphological defects and sensitivity to envelope stressors. Transposon insertion sequencing analysis of ibaG's genetic interactions suggested that ibaG is involved in several processes involved in the generation and homeostasis of the cell envelope. Furthermore, copurification studies revealed that IbaG interacts with proteins containing iron-sulfur clusters or involved in their assembly. Collectively, our findings suggest that V. cholerae IbaG controls cell morphology and cell envelope integrity through its role in biogenesis or trafficking of iron-sulfur cluster proteins.IMPORTANCE BolA-like proteins are conserved across prokaryotes and eukaryotes. These proteins have been linked to a variety of phenotypes, but the pathways and mechanisms through which they act have not been extensively characterized. Here, we unraveled the role of the BolA-like protein IbaG in the cholera pathogen Vibrio cholerae The absence of IbaG was associated with dramatic changes in cell morphology, sensitivity to envelope stressors, and intestinal colonization defects. IbaG was found to be required for biogenesis of several components of the V. cholerae cell envelope and to interact with numerous iron-sulfur cluster-containing proteins and factors involved in their assembly. Thus, our findings suggest that IbaG governs V. cholerae cell shape and cell envelope homeostasis through its effects on iron-sulfur proteins and associated pathways. The diversity of processes involving iron-sulfur-containing proteins is likely a factor underlying the range of phenotypes associated with BolA family proteins.
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55
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Jorgenson MA, MacCain WJ, Meberg BM, Kannan S, Bryant JC, Young KD. Simultaneously inhibiting undecaprenyl phosphate production and peptidoglycan synthases promotes rapid lysis in Escherichia coli. Mol Microbiol 2019; 112:233-248. [PMID: 31022322 PMCID: PMC6616000 DOI: 10.1111/mmi.14265] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/21/2019] [Indexed: 01/08/2023]
Abstract
Peptidoglycan (PG) is a highly cross-linked polysaccharide that encases bacteria, resists the effects of turgor and confers cell shape. PG precursors are translocated across the cytoplasmic membrane by the lipid carrier undecaprenyl phosphate (Und-P) where they are incorporated into the PG superstructure. Previously, we found that one of our Escherichia coli laboratory strains (CS109) harbors a missense mutation in uppS, which encodes an enzymatically defective Und-P(P) synthase. Here, we show that CS109 cells lacking the bifunctional aPBP PBP1B (penicillin binding protein 1B) lyse during exponential growth at elevated temperature. PBP1B lysis was reversed by: (i) reintroducing wild-type uppS, (ii) increasing the availability of PG precursors or (iii) overproducing PBP1A, a related bifunctional PG synthase. In addition, inhibiting the catalytic activity of PBP2 or PBP3, two monofunctional bPBPs, caused CS109 cells to lyse. Limiting the precursors required for Und-P synthesis in MG1655, which harbors a wild-type allele of uppS, also promoted lysis in mutants lacking PBP1B or bPBP activity. Thus, simultaneous inhibition of Und-P production and PG synthases provokes a synergistic response that leads to cell lysis. These findings suggest a biological connection that could be exploited in combination therapies.
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Affiliation(s)
- Matthew A. Jorgenson
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA,Corresponding author:
| | - William J. MacCain
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Bernadette M. Meberg
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
| | - Suresh Kannan
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Joseph C. Bryant
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Kevin D. Young
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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56
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Abstract
Peptidoglycan is an essential macromolecule that forms the bacterial cell wall. The recent discovery of new cell wall-polymerizing enzymes not only illuminates the basic biology and evolution of prokaryotes but also provides new targets for the development of antibacterials to combat drug-resistant pathogens.
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57
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Mueller EA, Egan AJ, Breukink E, Vollmer W, Levin PA. Plasticity of Escherichia coli cell wall metabolism promotes fitness and antibiotic resistance across environmental conditions. eLife 2019; 8:40754. [PMID: 30963998 PMCID: PMC6456298 DOI: 10.7554/elife.40754] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Accepted: 03/23/2019] [Indexed: 11/13/2022] Open
Abstract
Although the peptidoglycan cell wall is an essential structural and morphological feature of most bacterial cells, the extracytoplasmic enzymes involved in its synthesis are frequently dispensable under standard culture conditions. By modulating a single growth parameter-extracellular pH-we discovered a subset of these so-called 'redundant' enzymes in Escherichia coli are required for maximal fitness across pH environments. Among these pH specialists are the class A penicillin binding proteins PBP1a and PBP1b; defects in these enzymes attenuate growth in alkaline and acidic conditions, respectively. Genetic, biochemical, and cytological studies demonstrate that synthase activity is required for cell wall integrity across a wide pH range and influences pH-dependent changes in resistance to cell wall active antibiotics. Altogether, our findings reveal previously thought to be redundant enzymes are instead specialized for distinct environmental niches. This specialization may ensure robust growth and cell wall integrity in a wide range of conditions. Editorial note This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).
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Affiliation(s)
- Elizabeth A Mueller
- Department of Biology, Washington University in St. Louis, St. Louis, United States
| | - Alexander Jf Egan
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Eefjan Breukink
- Membrane Biochemistry and Biophysics, Department of Chemistry, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Petra Anne Levin
- Department of Biology, Washington University in St. Louis, St. Louis, United States
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58
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Roles of the DedD Protein in Escherichia coli Cell Constriction. J Bacteriol 2019; 201:JB.00698-18. [PMID: 30692172 DOI: 10.1128/jb.00698-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 01/20/2019] [Indexed: 02/04/2023] Open
Abstract
Two key tasks of the bacterial septal-ring (SR) machinery during cell constriction are the generation of an inward-growing annulus of septal peptidoglycan (sPG) and the concomitant splitting of its outer edge into two layers of polar PG that will be inherited by the two new cell ends. FtsN is an essential SR protein that helps trigger the active constriction phase in Escherichia coli by inducing a self-enhancing cycle of processes that includes both sPG synthesis and splitting and that we refer to as the sPG loop. DedD is an SR protein that resembles FtsN in several ways. Both are bitopic inner membrane proteins with small N-terminal cytoplasmic parts and larger periplasmic parts that terminate with a SPOR domain. Though absence of DedD normally causes a mild cell-chaining phenotype, the protein is essential for division and survival of cells with limited FtsN activity. Here, we find that a small N-terminal portion of DedD (NDedD; DedD1-54) is required and sufficient to suppress ΔdedD-associated division phenotypes, and we identify residues within its transmembrane domain that are particularly critical to DedD function. Further analyses indicate that DedD and FtsN act in parallel to promote sPG synthesis, possibly by engaging different parts of the FtsBLQ subcomplex to induce a conformation that permits and/or stimulates the activity of sPG synthase complexes composed of FtsW, FtsI (PBP3), and associated proteins. We propose that, like FtsN, DedD promotes cell fission by stimulating sPG synthesis, as well as by providing positive feedback to the sPG loop.IMPORTANCE Cell division (cytokinesis) is a fundamental biological process that is incompletely understood for any organism. Division of bacterial cells relies on a ring-like machinery called the septal ring or divisome that assembles along the circumference of the mother cell at the site where constriction eventually occurs. In the well-studied bacterium Escherichia coli, this machinery contains over 30 distinct proteins. We identify functionally important parts of one of these proteins, DedD, and present evidence supporting a role for DedD in helping to induce and/or sustain a self-enhancing cycle of processes that are executed by fellow septal-ring proteins and that drive the active constriction phase of the cell division cycle.
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59
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Vermassen A, Leroy S, Talon R, Provot C, Popowska M, Desvaux M. Cell Wall Hydrolases in Bacteria: Insight on the Diversity of Cell Wall Amidases, Glycosidases and Peptidases Toward Peptidoglycan. Front Microbiol 2019; 10:331. [PMID: 30873139 PMCID: PMC6403190 DOI: 10.3389/fmicb.2019.00331] [Citation(s) in RCA: 179] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 02/08/2019] [Indexed: 11/13/2022] Open
Abstract
The cell wall (CW) of bacteria is an intricate arrangement of macromolecules, at least constituted of peptidoglycan (PG) but also of (lipo)teichoic acids, various polysaccharides, polyglutamate and/or proteins. During bacterial growth and division, there is a constant balance between CW degradation and biosynthesis. The CW is remodeled by bacterial hydrolases, whose activities are carefully regulated to maintain cell integrity or lead to bacterial death. Each cell wall hydrolase (CWH) has a specific role regarding the PG: (i) cell wall amidase (CWA) cleaves the amide bond between N-acetylmuramic acid and L-alanine residue at the N-terminal of the stem peptide, (ii) cell wall glycosidase (CWG) catalyses the hydrolysis of the glycosidic linkages, whereas (iii) cell wall peptidase (CWP) cleaves amide bonds between amino acids within the PG chain. After an exhaustive overview of all known conserved catalytic domains responsible for CWA, CWG, and CWP activities, this review stresses that the CWHs frequently display a modular architecture combining multiple and/or different catalytic domains, including some lytic transglycosylases as well as CW binding domains. From there, direct physiological and collateral roles of CWHs in bacterial cells are further discussed.
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Affiliation(s)
- Aurore Vermassen
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
| | - Sabine Leroy
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
| | - Régine Talon
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
| | | | - Magdalena Popowska
- Department of Applied Microbiology, Faculty of Biology, Institute of Microbiology, University of Warsaw, Warsaw, Poland
| | - Mickaël Desvaux
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
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60
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Hsu YP, Hall E, Booher G, Murphy B, Radkov AD, Yablonowski J, Mulcahey C, Alvarez L, Cava F, Brun YV, Kuru E, VanNieuwenhze MS. Fluorogenic D-amino acids enable real-time monitoring of peptidoglycan biosynthesis and high-throughput transpeptidation assays. Nat Chem 2019; 11:335-341. [PMID: 30804500 PMCID: PMC6444347 DOI: 10.1038/s41557-019-0217-x] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 01/10/2019] [Indexed: 01/09/2023]
Abstract
Peptidoglycan (PG) is an essential cell wall component that maintains the morphology and viability of nearly all bacteria. Its biosynthesis requires periplasmic transpeptidation reactions which construct peptide cross-linkages between polysaccharide chains to endow mechanical strength. However, tracking transpeptidation reaction in vivo and in vitro is challenging, mainly due to the lack of efficient, biocompatible probes. Here, we report the design, synthesis, and application of rotor-fluorogenic D-amino acids (RfDAAs) enabling real-time, continuous tracking of transpeptidation reactions. These probes enable monitoring PG biosynthesis in real time through visualizing transpeptidase reactions in live cells, as well as real-time activity assays of D,D-, L,D-transpeptidases, and sortases in vitro. The unique ability of RfDAAs to become fluorescent when incorporated into PG provides a powerful new tool to study PG biosynthesis with high temporal resolution and prospectively enable high-throughput screening for inhibitors of PG biosynthesis.
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Affiliation(s)
- Yen-Pang Hsu
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Edward Hall
- Department of Chemistry, Indiana University, Bloomington, IN, USA.,Department of Chemistry, Hanover College, Hanover, IN, USA
| | - Garrett Booher
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Brennan Murphy
- Department of Chemistry, Indiana University, Bloomington, IN, USA
| | - Atanas D Radkov
- Department of Chemistry, Indiana University, Bloomington, IN, USA.,Department of Biophysics and Biochemistry, University of California San Francisco, San Francisco, CA, USA
| | - Jacob Yablonowski
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Caitlyn Mulcahey
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Laura Alvarez
- Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Felipe Cava
- Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Yves V Brun
- Department of Biology, Indiana University, Bloomington, IN, USA. .,Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Pavillon Roger-Gaudry, C.P. 6128, Succursale Centre-ville, Montréal, Canada.
| | - Erkin Kuru
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA. .,Department of Genetics, Harvard Medical School, Boston, MA, USA.
| | - Michael S VanNieuwenhze
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA. .,Department of Chemistry, Indiana University, Bloomington, IN, USA.
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61
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Hu J, Lu X, Wang H, Wang F, Zhao Y, Shen W, Yang H, Chen X. Enhancing extracellular protein production in Escherichia coli by deleting the d-alanyl-d-alanine carboxypeptidase gene dacC. Eng Life Sci 2019; 19:270-278. [PMID: 32625007 DOI: 10.1002/elsc.201800199] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 01/03/2019] [Accepted: 01/18/2019] [Indexed: 12/24/2022] Open
Abstract
d-Alanyl-d-alanine carboxypeptidase DacC is important for synthesis and stabilization of the peptidoglycan layer of Escherichia coli. In this work, dacC of E. coli BL21 (DE3) was successfully deleted, and the effects of this deletion on extracellular protein production in E. coli were investigated. The extracellular activities and fluorescence value of recombinant amylase, green fluorescent protein, and α-galactosidase of the deletion mutants were increased by 82.3, 29.1, and 37.7%, respectively, compared with that of control cells. The outer membrane permeability and intracellular soluble peptidoglycan accumulation of deletion mutant were also enhanced compared with those of control cells, respectively. Based on fluorescence-assisted cell sorting analyses, we found that the morphology of the E. coli deletion mutant cells was altered compared with that of control cells. Local transparent bulges in the poles of the E. coli mutant with deletion of the dacC gene were found by transmission electron microscopy analysis. These bulges in the poles could explain the improvement in the production of extracellular protein by the E. coli mutant with deletion of the dacC gene. These findings provide important insights into the extracellular production of proteins using E. coli as microbial cell factories.
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Affiliation(s)
- Jinyuan Hu
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology Ministry of Education Jiangnan University Wuxi P. R. China.,School of Biotechnology Jiangnan University Wuxi P. R. China
| | - Xiao Lu
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology Ministry of Education Jiangnan University Wuxi P. R. China.,School of Biotechnology Jiangnan University Wuxi P. R. China
| | - Haokun Wang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology Ministry of Education Jiangnan University Wuxi P. R. China.,School of Biotechnology Jiangnan University Wuxi P. R. China
| | - Fuxiang Wang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology Ministry of Education Jiangnan University Wuxi P. R. China.,School of Biotechnology Jiangnan University Wuxi P. R. China
| | - Yuan Zhao
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology Ministry of Education Jiangnan University Wuxi P. R. China.,School of Chemical and Material Engineering Jiangnan University Wuxi P. R. China
| | - Wei Shen
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology Ministry of Education Jiangnan University Wuxi P. R. China.,School of Biotechnology Jiangnan University Wuxi P. R. China
| | - Haiquan Yang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology Ministry of Education Jiangnan University Wuxi P. R. China.,School of Biotechnology Jiangnan University Wuxi P. R. China
| | - Xianzhong Chen
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology Ministry of Education Jiangnan University Wuxi P. R. China.,School of Biotechnology Jiangnan University Wuxi P. R. China
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62
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Regulation of the Peptidoglycan Polymerase Activity of PBP1b by Antagonist Actions of the Core Divisome Proteins FtsBLQ and FtsN. mBio 2019; 10:mBio.01912-18. [PMID: 30622193 PMCID: PMC6325244 DOI: 10.1128/mbio.01912-18] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Peptidoglycan (PG) is an essential constituent of the bacterial cell wall. During cell division, PG synthesis localizes at midcell under the control of a multiprotein complex, the divisome, allowing the safe formation of two new cell poles and separation of daughter cells. Genetic studies in Escherichia coli pointed out that FtsBLQ and FtsN participate in the regulation of septal PG (sPG) synthesis; however, the underlying molecular mechanisms remained largely unknown. Here we show that FtsBLQ subcomplex directly interacts with the PG synthase PBP1b and with the subcomplex FtsW-PBP3, mainly via FtsW. Strikingly, we discovered that FtsBLQ inhibits the glycosyltransferase activity of PBP1b and that this inhibition was antagonized by the PBP1b activators FtsN and LpoB. The same results were obtained in the presence of FtsW-PBP3. Moreover, using a simple thioester substrate (S2d), we showed that FtsBLQ also inhibits the transpeptidase domain of PBP3 but not of PBP1b. As the glycosyltransferase and transpeptidase activities of PBP1b are coupled and PBP3 activity requires nascent PG substrate, the results suggest that PBP1b inhibition by FtsBLQ will block sPG synthesis by these enzymes, thus maintaining cell division as repressed until the maturation of the divisome is signaled by the accumulation of FtsN, which triggers sPG synthesis and the initiation of cell constriction. These results confirm that PBP1b plays an important role in E. coli cell division and shed light on the specific role of FtsN, which seems to counterbalance the inhibitory effect of FtsBLQ to restore PBP1b activity.IMPORTANCE Bacterial cell division is governed by a multiprotein complex called divisome, which facilitates a precise cell wall synthesis at midcell and daughter cell separation. Protein-protein interactions and activity studies using different combinations of the septum synthesis core of the divisome revealed that the glycosyltransferase activity of PBP1b is repressed by FtsBLQ and that the presence of FtsN or LpoB suppresses this inhibition. Moreover, FtsBLQ also inhibits the PBP3 activity on a thioester substrate. These results provide enzymatic evidence of the regulation of the peptidoglycan synthase PBP1b and PBP3 within the divisome. The results confirm that PBP1b plays an important role in E. coli cell division and shed light on the specific role of FtsN, which functions to relieve the repression on PBP1b by FtsBLQ and to initiate septal peptidoglycan synthesis.
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63
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Juan C, Torrens G, Barceló IM, Oliver A. Interplay between Peptidoglycan Biology and Virulence in Gram-Negative Pathogens. Microbiol Mol Biol Rev 2018; 82:e00033-18. [PMID: 30209071 PMCID: PMC6298613 DOI: 10.1128/mmbr.00033-18] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The clinical and epidemiological threat of the growing antimicrobial resistance in Gram-negative pathogens, particularly for β-lactams, the most frequently used and relevant antibiotics, urges research to find new therapeutic weapons to combat the infections caused by these microorganisms. An essential previous step in the development of these therapeutic solutions is to identify their potential targets in the biology of the pathogen. This is precisely what we sought to do in this review specifically regarding the barely exploited field analyzing the interplay among the biology of the peptidoglycan and related processes, such as β-lactamase regulation and virulence. Hence, here we gather, analyze, and integrate the knowledge derived from published works that provide information on the topic, starting with those dealing with the historically neglected essential role of the Gram-negative peptidoglycan in virulence, including structural, biogenesis, remodeling, and recycling aspects, in addition to proinflammatory and other interactions with the host. We also review the complex link between intrinsic β-lactamase production and peptidoglycan metabolism, as well as the biological costs potentially associated with the expression of horizontally acquired β-lactamases. Finally, we analyze the existing evidence from multiple perspectives to provide useful clues for identifying targets enabling the future development of therapeutic options attacking the peptidoglycan-virulence interconnection as a key weak point of the Gram-negative pathogens to be used, if not to kill the bacteria, to mitigate their capacity to produce severe infections.
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Affiliation(s)
- Carlos Juan
- Servicio de Microbiología and Unidad de Investigación, Hospital Son Espases, Instituto de Investigación Sanitaria de Baleares (IdISBa), Palma, Spain
| | - Gabriel Torrens
- Servicio de Microbiología and Unidad de Investigación, Hospital Son Espases, Instituto de Investigación Sanitaria de Baleares (IdISBa), Palma, Spain
| | - Isabel Maria Barceló
- Servicio de Microbiología and Unidad de Investigación, Hospital Son Espases, Instituto de Investigación Sanitaria de Baleares (IdISBa), Palma, Spain
| | - Antonio Oliver
- Servicio de Microbiología and Unidad de Investigación, Hospital Son Espases, Instituto de Investigación Sanitaria de Baleares (IdISBa), Palma, Spain
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64
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Pazos M, Peters K, Casanova M, Palacios P, VanNieuwenhze M, Breukink E, Vicente M, Vollmer W. Z-ring membrane anchors associate with cell wall synthases to initiate bacterial cell division. Nat Commun 2018; 9:5090. [PMID: 30504892 PMCID: PMC6269477 DOI: 10.1038/s41467-018-07559-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 11/08/2018] [Indexed: 12/29/2022] Open
Abstract
During the transition from elongation to septation, Escherichia coli establishes a ring-like peptidoglycan growth zone at the future division site. This preseptal peptidoglycan synthesis does not require the cell division-specific peptidoglycan transpeptidase PBP3 or most of the other cell division proteins, but it does require FtsZ, its membrane-anchor ZipA and at least one of the bi-functional transglycosylase-transpeptidases, PBP1A or PBP1B. Here we show that PBP1A and PBP1B interact with ZipA and localise to preseptal sites in cells with inhibited PBP3. ZipA stimulates the glycosyltransferase activity of PBP1A. The membrane-anchored cell division protein FtsN localises at preseptal sites and stimulates both activities of PBP1B. Genes zipA and ftsN can be individually deleted in ftsA* mutant cells, but the simultaneous depletion of both proteins is lethal and cells do not establish preseptal sites. Our data support a model according to which ZipA and FtsN-FtsA have semi-redundant roles in connecting the cytosolic FtsZ ring with the membrane-anchored peptidoglycan synthases during the preseptal phase of envelope growth. Proteins FtsZ, ZipA, and either PBP1A or PBP1B are required for the synthesis of preseptal peptidoglycan at the future cell division site in E. coli. Here, Pazos et al. provide evidence that ZipA and FtsA-FtsN connect the cytosolic FtsZ ring with the membrane-anchored PBPs.
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Affiliation(s)
- Manuel Pazos
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK
| | - Katharina Peters
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK
| | - Mercedes Casanova
- Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Darwin 3, 28049, Madrid, Spain
| | - Pilar Palacios
- Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Darwin 3, 28049, Madrid, Spain
| | - Michael VanNieuwenhze
- Molecular and Cellular Biochemistry Department, Biology Department, Indiana University, 212S. Hawthorne Dr, Bloomington, IN, 47405, USA
| | - Eefjan Breukink
- Membrane Biochemistry and Biophysics, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Miguel Vicente
- Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Darwin 3, 28049, Madrid, Spain
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK.
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65
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Kumar S, Rubino FA, Mendoza AG, Ruiz N. The bacterial lipid II flippase MurJ functions by an alternating-access mechanism. J Biol Chem 2018; 294:981-990. [PMID: 30482840 DOI: 10.1074/jbc.ra118.006099] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 11/14/2018] [Indexed: 11/06/2022] Open
Abstract
The peptidoglycan (PG) cell wall is an essential extracytoplasmic glycopeptide polymer that safeguards bacteria against osmotic lysis and determines cellular morphology. Bacteria use multiprotein machineries for the synthesis of the PG cell wall during cell division and elongation that can be targeted by antibiotics such as the β-lactams. Lipid II, the lipid-linked precursor for PG biogenesis, is synthesized in the inner leaflet of the cytoplasmic membrane and then translocated across the bilayer, where it is ultimately polymerized into PG. In Escherichia coli, MurJ, a member of the MOP exporter superfamily, has been recently shown to have lipid II flippase activity that depends on membrane potential. Because of its essentiality, MurJ could potentially be targeted by much needed novel antibiotics. Recent structural information suggests that a central cavity in MurJ alternates between inward- and outward-open conformations to flip lipid II, but how these conformational changes occur are unknown. Here, we utilized structure-guided cysteine cross-linking and proteolysis-coupled gel analysis to probe the conformational changes of MurJ in E. coli cells. We found that paired cysteine substitutions in transmembrane domains 2 and 8 and periplasmic loops of MurJ could be cross-linked with homobifunctional cysteine cross-linkers, indicating that MurJ can adopt both inward- and outward-facing conformations in vivo Furthermore, we show that dissipating the membrane potential with an ionophore decreases the prevalence of the inward-facing, but not the outward-facing state. Our study provides in vivo evidence that MurJ uses an alternating-access mechanism during the lipid II transport cycle.
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Affiliation(s)
- Sujeet Kumar
- From the Department of Microbiology, The Ohio State University, Columbus, Ohio 43210 and
| | - Frederick A Rubino
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138
| | - Alicia G Mendoza
- From the Department of Microbiology, The Ohio State University, Columbus, Ohio 43210 and
| | - Natividad Ruiz
- From the Department of Microbiology, The Ohio State University, Columbus, Ohio 43210 and
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66
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Improving extracellular protein production in Escherichia coli by overexpressing D,D-carboxypeptidase to perturb peptidoglycan network synthesis and structure. Appl Microbiol Biotechnol 2018; 103:793-806. [DOI: 10.1007/s00253-018-9510-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 11/01/2018] [Accepted: 11/07/2018] [Indexed: 12/26/2022]
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67
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Egan AJF, Maya-Martinez R, Ayala I, Bougault CM, Banzhaf M, Breukink E, Vollmer W, Simorre JP. Induced conformational changes activate the peptidoglycan synthase PBP1B. Mol Microbiol 2018; 110:335-356. [PMID: 30044025 PMCID: PMC6220978 DOI: 10.1111/mmi.14082] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/12/2018] [Indexed: 12/25/2022]
Abstract
Bacteria surround their cytoplasmic membrane with an essential, stress‐bearing peptidoglycan (PG) layer consisting of glycan chains linked by short peptides into a mesh‐like structure. Growing and dividing cells expand their PG layer using inner‐membrane anchored PG synthases, including Penicillin‐binding proteins (PBPs), which participate in dynamic protein complexes to facilitate cell wall growth. In Escherichia coli, and presumably other Gram‐negative bacteria, growth of the mainly single layered PG is regulated by outer membrane‐anchored lipoproteins. The lipoprotein LpoB is required to activate PBP1B, which is a major, bi‐functional PG synthase with glycan chain polymerising (glycosyltransferase) and peptide cross‐linking (transpeptidase) activities. In this work we show how the binding of LpoB to the regulatory UB2H domain of PBP1B activates both activities. Binding induces structural changes in the UB2H domain, which transduce to the two catalytic domains by distinct allosteric pathways. We also show how an additional regulator protein, CpoB, is able to selectively modulate the TPase activation by LpoB without interfering with GTase activation.
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Affiliation(s)
- Alexander J F Egan
- The Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK
| | - Roberto Maya-Martinez
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CNRS, CEA, 71 avenue des Martyrs, 38000, Grenoble, France
| | - Isabel Ayala
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CNRS, CEA, 71 avenue des Martyrs, 38000, Grenoble, France
| | - Catherine M Bougault
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CNRS, CEA, 71 avenue des Martyrs, 38000, Grenoble, France
| | - Manuel Banzhaf
- European Molecular Biology Laboratory Heidelberg, Genome Biology Unit, Meyerhofstraße 1, 69117, Heidelberg, Germany.,Institute of Microbiology & Infection and School of Biosciences, University of Birmingham, Edgbaston, Birmingham , B15 2TT, UK
| | - Eefjan Breukink
- Bijvoet Center for Biomolecular Research, Department of Biochemistry of Membranes, University of Utrecht, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Waldemar Vollmer
- The Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK
| | - Jean-Pierre Simorre
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CNRS, CEA, 71 avenue des Martyrs, 38000, Grenoble, France
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68
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Boosting Secretion of Extracellular Protein by Escherichia coli via Cell Wall Perturbation. Appl Environ Microbiol 2018; 84:AEM.01382-18. [PMID: 30097440 DOI: 10.1128/aem.01382-18] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 07/20/2018] [Indexed: 01/16/2023] Open
Abstract
Escherichia coli is one of the most widely used host microorganisms for recombinant protein expression and metabolic engineering, but it cannot efficiently secrete recombinant proteins to extracellular space. Here, extracellular protein secretion was enhanced in E. coli by deleting two d,d-carboxypeptidase genes (dacA and dacB, single and double deletions) to perturb the cell wall peptidoglycan network. Deletion of dacA and dacB enhanced the accumulation of intracellular soluble peptidoglycan in E. coli and affected cell morphology, resulting in a more irregular cell shape and the appearance of transparent bulges. Deletion of dacA and dacB appears to disrupt the normal rigid structure, presumably due to perturbation and destruction of the cell wall peptidoglycan network. The extracellular green fluorescent protein (GFP) fluorescence intensity of deletion mutants was increased by >2.0-fold compared with that of control cells, and that of the double deletion mutant was increased by 2.7-fold. Extracellular recombinant fibroblast growth factor receptor 2 (FGFR2) and collagen E4 secretion in deletion mutants was also enhanced compared with that in the control cells. Additionally, the extracellular recombinant amylase activity of single-deletion mutants BL21 ΔdacA pETDuet-amyk and BL21 ΔdacB pETDuet-amyk was increased 2.5- and 3.1-fold, respectively. The extracellular distribution of α-galactosidase by deletion mutants was also increased by >2.0-fold. Deletion of dacA and dacB increased outer membrane permeability, which could explain the enhanced extracellular protein secretion.IMPORTANCE Cell surface structure stabilization is important for extracellular secretion of proteins in Escherichia coli As the main constituent of the cell wall, peptidoglycan contributes to cell structure robustness and stability. Here, we perturbed the peptidoglycan network by deleting dacA and dacB genes encoding d,d-carboxypeptidase enzymes to improve extracellular protein secretion. This new strategy could enhance the capacity of E. coli as a microbial cell factory for extracellular secretion of proteins and chemicals.
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69
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Sychantha D, Brott AS, Jones CS, Clarke AJ. Mechanistic Pathways for Peptidoglycan O-Acetylation and De-O-Acetylation. Front Microbiol 2018; 9:2332. [PMID: 30327644 PMCID: PMC6174289 DOI: 10.3389/fmicb.2018.02332] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 09/11/2018] [Indexed: 12/22/2022] Open
Abstract
The post-synthetic O-acetylation of the essential component of bacterial cell walls, peptidoglycan (PG), is performed by many pathogenic bacteria to help them evade the lytic action of innate immunity responses. Occurring at the C-6 hydroxyl of N-acetylmuramoyl residues, this modification to the glycan backbone of PG sterically blocks the activity of lysozymes. As such, the enzyme responsible for this modification in Gram-positive bacteria is recognized as a virulence factor. With Gram-negative bacteria, the O-acetylation of PG provides a means of control of their autolysins at the substrate level. In this review, we discuss the pathways for PG O-acetylation and de-O-acetylation and the structure and function relationship of the O-acetyltransferases and O-acetylesterases that catalyze these reactions. The current understanding of their mechanisms of action is presented and the prospects of targeting these systems for the development of novel therapeutics are explored.
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Affiliation(s)
| | | | | | - Anthony J. Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
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70
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Geiger T, Pazos M, Lara-Tejero M, Vollmer W, Galán JE. Peptidoglycan editing by a specific LD-transpeptidase controls the muramidase-dependent secretion of typhoid toxin. Nat Microbiol 2018; 3:1243-1254. [PMID: 30250245 DOI: 10.1038/s41564-018-0248-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 08/20/2018] [Indexed: 01/26/2023]
Abstract
Protein secretion mechanisms are essential for the virulence of most bacterial pathogens. Typhoid toxin is an essential virulence factor for Salmonella Typhi, the cause of typhoid fever in humans. This toxin is unique in that it is only produced within mammalian cells, and it must be trafficked to the extracellular space before intoxicating target cells. An essential and poorly understood aspect of this transport pathway is the secretion of typhoid toxin from the bacterium into the S. Typhi-containing vacuole. We show here that typhoid toxin secretion requires its translocation to the trans side of the peptidoglycan layer at the bacterial poles for subsequent release through the outer membrane. This translocation process depends on a specialized muramidase, the activity of which requires the localized editing of peptidoglycan by a specific ld-transpeptidase. These studies describe a protein export mechanism that is probably conserved in other bacterial species.
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Affiliation(s)
- Tobias Geiger
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Manuel Pazos
- The Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK
| | - Maria Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Waldemar Vollmer
- The Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA.
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71
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Romaniuk JAH, Cegelski L. Peptidoglycan and Teichoic Acid Levels and Alterations in Staphylococcus aureus by Cell-Wall and Whole-Cell Nuclear Magnetic Resonance. Biochemistry 2018; 57:3966-3975. [PMID: 29806458 PMCID: PMC6309457 DOI: 10.1021/acs.biochem.8b00495] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Gram-positive bacteria surround themselves with a multilayered macromolecular cell wall that is essential to cell survival and serves as a major target for antibiotics. The cell wall of Staphylococcus aureus is composed of two major structural components, peptidoglycan (PG) and wall teichoic acid (WTA), together creating a heterogeneous and insoluble matrix that poses a challenge to quantitative compositional analysis. Here, we present 13C cross polarization magic angle spinning solid-state nuclear magnetic resonance (NMR) spectra of intact cell walls, purified PG, and purified WTA. The spectra reveal the clear molecular differences in the two polymers and enable quantification of PG and WTA in isolated cell walls, an attractive alternative to estimating teichoic acid content from a phosphate analysis of completely pyrolyzed cell walls. Furthermore, we discovered that unique PG and WTA spectral signatures could be identified in whole-cell NMR spectra and used to compare PG and WTA levels among intact bacterial cell samples. The distinguishing whole-cell 13C NMR contributions associated with PG include the GlcNAc-MurNAc sugar carbons and glycyl α-carbons. WTA contributes carbons from the phosphoribitol backbone. Distinguishing 15N spectral signatures include glycyl amide nitrogens in PG and the esterified d-alanyl amine nitrogens in WTA. 13C NMR analysis was performed with samples at natural abundance and included 10 whole-cell sample comparisons. Changes consistent with altered PG and WTA content were detected in whole-cell spectra of bacteria harvested at different growth times and in cells treated with tunicamycin. This use of whole-cell NMR provides quantitative parameters of composition in the context of whole-cell activity.
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Affiliation(s)
| | - Lynette Cegelski
- Stanford University, Department of Chemistry, 380 Roth Way, Stanford CA 94305
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72
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Dik DA, Fisher JF, Mobashery S. Cell-Wall Recycling of the Gram-Negative Bacteria and the Nexus to Antibiotic Resistance. Chem Rev 2018; 118:5952-5984. [PMID: 29847102 PMCID: PMC6855303 DOI: 10.1021/acs.chemrev.8b00277] [Citation(s) in RCA: 121] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The importance of the cell wall to the viability of the bacterium is underscored by the breadth of antibiotic structures that act by blocking key enzymes that are tasked with cell-wall creation, preservation, and regulation. The interplay between cell-wall integrity, and the summoning forth of resistance mechanisms to deactivate cell-wall-targeting antibiotics, involves exquisite orchestration among cell-wall synthesis and remodeling and the detection of and response to the antibiotics through modulation of gene regulation by specific effectors. Given the profound importance of antibiotics to the practice of medicine, the assertion that understanding this interplay is among the most fundamentally important questions in bacterial physiology is credible. The enigmatic regulation of the expression of the AmpC β-lactamase, a clinically significant and highly regulated resistance response of certain Gram-negative bacteria to the β-lactam antibiotics, is the exemplar of this challenge. This review gives a current perspective to this compelling, and still not fully solved, 35-year enigma.
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Affiliation(s)
- David A. Dik
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Jed F. Fisher
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame, Indiana 46556, United States
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73
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Bonnet J, Durmort C, Mortier-Barrière I, Campo N, Jacq M, Moriscot C, Straume D, Berg KH, Håvarstein L, Wong YS, Vernet T, Di Guilmi AM. Nascent teichoic acids insertion into the cell wall directs the localization and activity of the major pneumococcal autolysin LytA. ACTA ACUST UNITED AC 2018; 2:24-37. [PMID: 32743129 PMCID: PMC7389264 DOI: 10.1016/j.tcsw.2018.05.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 05/17/2018] [Accepted: 05/18/2018] [Indexed: 12/14/2022]
Abstract
Peptidoglycan which sustains bacterial growth is targeted by b-lactam antibiotics. Spread of antibiotic resistance requires the development of new antibacterial drugs. The cell wall of Gram-positive bacteria carries teichoic acids and virulence factors. Function and surface localization of virulence factors are regulated by teichoic acids. Anti-bacterial strategy should target the localization of surface virulence factors.
The bacterial cell wall is in part composed of the peptidoglycan (PG) layer that maintains the cell shape and sustains the basic cellular processes of growth and division. The cell wall of Gram-positive bacteria also carries teichoic acids (TAs). In this work, we investigated how TAs contribute to the structuration of the PG network through the modulation of PG hydrolytic enzymes in the context of the Gram-positive Streptococcus pneumoniae bacterium. Pneumococcal TAs are decorated by phosphorylcholine residues which serve as anchors for the Choline-Binding Proteins, some of them acting as PG hydrolases, like the major autolysin LytA. Their binding is non covalent and reversible, a property that allows easy manipulation of the system. In this work, we show that the release of LytA occurs independently from its amidase activity. Furthermore, LytA fused to GFP was expressed in pneumococcal cells and showed different localization patterns according to the growth phase. Importantly, we demonstrate that TAs modulate the enzymatic activity of LytA since a low level of TAs present at the cell surface triggers LytA sensitivity in growing pneumococcal cells. We previously developed a method to label nascent TAs in live cells revealing that the insertion of TAs into the cell wall occurs at the mid-cell. In conclusion, we demonstrate that nascent TAs inserted in the cell wall at the division site are the specific receptors of LytA, tuning in this way the positioning of LytA at the appropriate place at the cell surface.
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Affiliation(s)
- J Bonnet
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
| | - C Durmort
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
| | - I Mortier-Barrière
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, UPS, F-31000 Toulouse, France
| | - N Campo
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, UPS, F-31000 Toulouse, France
| | - M Jacq
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
| | - C Moriscot
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
| | - D Straume
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Aas, Norway
| | - K H Berg
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Aas, Norway
| | - L Håvarstein
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Aas, Norway
| | - Y-S Wong
- Département de Pharmacochimie Moléculaire (DPM), Univ. Grenoble Alpes, UMR 5063 CNRS, ICMG FR 2607, 38 041 Grenoble, France
| | - T Vernet
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
| | - A M Di Guilmi
- Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
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74
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Caveney NA, Li FK, Strynadka NC. Enzyme structures of the bacterial peptidoglycan and wall teichoic acid biogenesis pathways. Curr Opin Struct Biol 2018; 53:45-58. [PMID: 29885610 DOI: 10.1016/j.sbi.2018.05.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/08/2018] [Accepted: 05/16/2018] [Indexed: 01/08/2023]
Abstract
The bacterial cell wall is a complex polymeric structure with essential roles in defence, survival and pathogenesis. Common to both Gram-positive and Gram-negative bacteria is the mesh-like peptidoglycan sacculus that surrounds the outer leaflet of the cytoplasmic membrane. Recent crystallographic studies of enzymes that comprise the peptidoglycan biosynthetic pathway have led to significant new understanding of all stages. These include initial multi-step cytosolic formation of sugar-pentapeptide precursors, transfer of the precursors to activated polyprenyl lipids at the membrane inner leaflet and flippase mediated relocalization of the resulting lipid II precursors to the outer leaflet where glycopolymerization and subsequent peptide crosslinking are finalized. Additional, species-specific enzymes allow customized peptidoglycan modifications and biosynthetic regulation that are important to bacterial virulence and survival. These studies have reinforced the unique and specific catalytic mechanisms at play in cell wall biogenesis and expanded the atomic foundation to develop novel, structure guided, antibacterial agents.
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Affiliation(s)
- Nathanael A Caveney
- University of British Columbia, Biochemistry and Molecular Biology and the Center for Blood Research, Rm 4350 Life Sciences Center, 2350 Health Sciences Mall, Vancouver V6T 1Z3 Canada
| | - Franco Kk Li
- University of British Columbia, Biochemistry and Molecular Biology and the Center for Blood Research, Rm 4350 Life Sciences Center, 2350 Health Sciences Mall, Vancouver V6T 1Z3 Canada
| | - Natalie Cj Strynadka
- University of British Columbia, Biochemistry and Molecular Biology and the Center for Blood Research, Rm 4350 Life Sciences Center, 2350 Health Sciences Mall, Vancouver V6T 1Z3 Canada.
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75
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Hernández-Rocamora VM, Otten CF, Radkov A, Simorre JP, Breukink E, VanNieuwenhze M, Vollmer W. Coupling of polymerase and carrier lipid phosphatase prevents product inhibition in peptidoglycan synthesis. ACTA ACUST UNITED AC 2018; 2:1-13. [PMID: 30046664 PMCID: PMC6053597 DOI: 10.1016/j.tcsw.2018.04.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 04/13/2018] [Accepted: 04/13/2018] [Indexed: 11/30/2022]
Abstract
Peptidoglycan (PG) is an essential component of the bacterial cell wall that maintains the shape and integrity of the cell. The PG precursor lipid II is assembled at the inner leaflet of the cytoplasmic membrane, translocated to the periplasmic side, and polymerized to glycan chains by membrane anchored PG synthases, such as the class A Penicillin-binding proteins (PBPs). Polymerization of PG releases the diphosphate form of the carrier lipid, undecaprenyl pyrophosphate (C55-PP), which is converted to the monophosphate form by membrane-embedded pyrophosphatases, generating C55-P for a new round of PG precursor synthesis. Here we report that deletion of the C55-PP pyrophosphatase gene pgpB in E. coli increases the susceptibility to cefsulodin, a β-lactam specific for PBP1A, indicating that the cellular function of PBP1B is impaired in the absence of PgpB. Purified PBP1B interacted with PgpB and another C55-PP pyrophosphatase, BacA and both, PgpB and BacA stimulated the glycosyltransferase activity of PBP1B. C55-PP was found to be a potent inhibitor of PBP1B. Our data suggest that the stimulation of PBP1B by PgpB is due to the faster removal and processing of C55-PP, and that PBP1B interacts with C55-PP phosphatases during PG synthesis to couple PG polymerization with the recycling of the carrier lipid and prevent product inhibition by C55-PP.
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Affiliation(s)
- Víctor M Hernández-Rocamora
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK
| | - Christian F Otten
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK
| | - Atanas Radkov
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405-7102, USA
| | - Jean-Pierre Simorre
- Institut de Biologie Structurale, Université Grenoble Alpes, Grenoble, France
| | - Eefjan Breukink
- Membrane Biochemistry and Biophysics, Bijvoet Centre for Biomolecular Research, University of Utrecht, Padualaan 8, 3584 Utrecht, The Netherlands
| | - Michael VanNieuwenhze
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405-7102, USA
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, UK
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76
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Punekar AS, Samsudin F, Lloyd AJ, Dowson CG, Scott DJ, Khalid S, Roper DI. The role of the jaw subdomain of peptidoglycan glycosyltransferases for lipid II polymerization. Cell Surf 2018; 2:54-66. [PMID: 30046666 PMCID: PMC6053601 DOI: 10.1016/j.tcsw.2018.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 06/12/2018] [Accepted: 06/12/2018] [Indexed: 12/27/2022] Open
Abstract
Bacterial peptidoglycan glycosyltransferases (PGT) catalyse the essential polymerization of lipid II into linear glycan chains required for peptidoglycan biosynthesis. The PGT domain is composed of a large head subdomain and a smaller jaw subdomain and can be potently inhibited by the antibiotic moenomycin A (MoeA). We present an X-ray structure of the MoeA-bound Staphylococcus aureus monofunctional PGT enzyme, revealing electron density for a second MoeA bound to the jaw subdomain as well as the PGT donor site. Isothermal titration calorimetry confirms two drug-binding sites with markedly different affinities and positive cooperativity. Hydrophobic cluster analysis suggests that the membrane-interacting surface of the jaw subdomain has structural and physicochemical properties similar to amphipathic cationic α -helical antimicrobial peptides for lipid II recognition and binding. Furthermore, molecular dynamics simulations of the drug-free and -bound forms of the enzyme demonstrate the importance of the jaw subdomain movement for lipid II selection and polymerization process and provide molecular-level insights into the mechanism of peptidoglycan biosynthesis by PGTs.
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Affiliation(s)
- Avinash S. Punekar
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Firdaus Samsudin
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Adrian J. Lloyd
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | | | - David J. Scott
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Leicestershire LE12 5RD, United Kingdom
- ISIS Neutron and Muon Spallation Source and Research Complex at Harwell, Rutherford Appleton Laboratory, Oxfordshire, United Kingdom
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - David I. Roper
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
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77
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den Blaauwen T. Is Longitudinal Division in Rod-Shaped Bacteria a Matter of Swapping Axis? Front Microbiol 2018; 9:822. [PMID: 29867786 PMCID: PMC5952006 DOI: 10.3389/fmicb.2018.00822] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Accepted: 04/11/2018] [Indexed: 01/21/2023] Open
Abstract
The morphology of bacterial species shows a wealth of variation from star-shaped to spherical and rod- to spiral-shaped, to mention a few. Their mode of growth and division is also very diverse and flexible ranging from polar growth and lateral surface increase to midcell expansion and from perpendicular to longitudinal asymmetric division. Gammaproteobacterial rod-shaped species such as Escherchia coli divide perpendicularly and grow in length, whereas the genetically very similar rod-shaped symbiotic Thiosymbion divide longitudinally, and some species even divide asynchronously while growing in width. The ovococcal Streptococcus pneumoniae also lengthens and divides perpendicularly, yet it is genetically very different from E. coli. Are these differences as dramatic as is suggested by visual inspection, or can they all be achieved by subtle variation in the regulation of the same protein complexes that synthesize the cell envelope? Most bacteria rely on the cytoskeletal polymer FtsZ to organize cell division, but only a subset of species use the actin homolog MreB for length growth, although some of them are morphologically not that different. Poles are usually negative determinant for cell division. Curved cell poles can be inert or active with respect to peptidoglycan synthesis, can localize chemotaxis and other sensing proteins or other bacterial equipment, such as pili, depending on the species. But what is actually the definition of a pole? This review discusses the possible common denominators for growth and division of distinct and similar bacterial species.
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Affiliation(s)
- Tanneke den Blaauwen
- Bacterial Cell Biology and Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
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78
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Meyer K, Addy C, Akashi S, Roper DI, Tame JR. The crystal structure and oligomeric form of Escherichia coli l , d -carboxypeptidase A. Biochem Biophys Res Commun 2018; 499:594-599. [DOI: 10.1016/j.bbrc.2018.03.195] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 03/26/2018] [Indexed: 11/16/2022]
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79
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Spidlova P, Stojkova P, Dankova V, Senitkova I, Santic M, Pinkas D, Philimonenko V, Stulik J. Francisella tularensis D-Ala D-Ala Carboxypeptidase DacD Is Involved in Intracellular Replication and It Is Necessary for Bacterial Cell Wall Integrity. Front Cell Infect Microbiol 2018; 8:111. [PMID: 29692981 PMCID: PMC5903032 DOI: 10.3389/fcimb.2018.00111] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/21/2018] [Indexed: 12/16/2022] Open
Abstract
D-alanyl-D-alanine carboxypeptidase, product of dacD gene in Francisella, belongs to penicillin binding proteins (PBPs) and is involved in remodeling of newly synthetized peptidoglycan. In E. coli, PBPs are synthetized in various growth phases and they are able to substitute each other to a certain extent. The DacD protein was found to be accumulated in fraction enriched in membrane proteins from severely attenuated dsbA deletion mutant strain. It has been presumed that the DsbA is not a virulence factor by itself but that its substrates, whose correct folding and topology are dependent on the DsbA oxidoreductase and/or isomerase activities, are the primary virulence factors. Here we demonstrate that Francisella DacD is required for intracellular replication and virulence in mice. The dacD insertion mutant strain showed higher sensitivity to acidic pH, high temperature and high osmolarity when compared to the wild-type. Eventually, transmission electron microscopy revealed differences in mutant bacteria in both the size and defects in outer membrane underlying its SDS and serum sensitivity. Taken together these results suggest DacD plays an important role in Francisella pathogenicity.
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Affiliation(s)
- Petra Spidlova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Pavla Stojkova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Vera Dankova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Iva Senitkova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
| | - Marina Santic
- Department of Microbiology and Parasitology, Medical Faculty, University of Rijeka, Rijeka, Croatia
| | - Dominik Pinkas
- Microscopy Center, Institute of Molecular Genetics ASCR v.v.i., Electron Microscopy Core Facility, Prague, Czechia
| | - Vlada Philimonenko
- Microscopy Center, Institute of Molecular Genetics ASCR v.v.i., Electron Microscopy Core Facility, Prague, Czechia
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics ASCR v.v.i., Prague, Czechia
| | - Jiri Stulik
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
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80
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Adediran SA, Sarkar KS, Pratt RF. Kinetic Evidence for a Second Ligand Binding Site on Streptococcus pneumoniae Penicillin-Binding Protein 2x. Biochemistry 2018; 57:1758-1766. [PMID: 29485264 DOI: 10.1021/acs.biochem.7b01209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
High molecular mass penicillin-binding proteins (PBPs, DD-peptidases) of class B, such as Streptococcus pneumoniae PBP2x, catalyze the cross-linking of peptidoglycan in bacterial cell wall biosynthesis and are thus important antibiotic targets. Despite their importance in this regard, structure-function studies of ligands of these enzymes have been impeded by the absence of useful substrates. In vitro, these enzymes do not catalyze peptide hydrolysis or aminolysis, their in vivo reaction, but some, such as PBP2x, do catalyze these reactions of certain thioesters such as PhCH2CONHCH2COSCH(D-Me)CO2- (2). We have now prepared several peptidoglycan-mimetic thioesters that we expected to more closely resemble the natural substrates of these enzymes. To our surprise, however, these compounds, although indeed substrates of PBP2x, did not, unlike 2, appear to form an acyl-enzyme intermediate during hydrolysis, and their turnover was inhibited by certain peptides and N-acylamino acids much more weakly than that of 2. An inhibitor of this type, N-benzyloxycarbonyl-d-glutamic acid, also quenched the fluorescence of PBP2x that had been labeled at the DD-peptidase active site by 6-dansylamidopenicillanic acid. These results were interpreted in terms of a model where the peptidoglycan-mimetic thioesters preferentially bound to and hydrolyzed at a site other than the classical DD-peptidase active site. This second site is likely to represent part of an extended binding site that accommodates a peptidoglycan substrate or regulator in vivo. Such a site may be a target for future inhibitor/antibiotic design.
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Affiliation(s)
- S A Adediran
- Department of Chemistry , Wesleyan University , Lawn Avenue , Middletown , Connecticut 06459 , United States
| | - Kumar Subarno Sarkar
- Department of Chemistry , Wesleyan University , Lawn Avenue , Middletown , Connecticut 06459 , United States
| | - R F Pratt
- Department of Chemistry , Wesleyan University , Lawn Avenue , Middletown , Connecticut 06459 , United States
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81
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Egan AJF. Bacterial outer membrane constriction. Mol Microbiol 2018; 107:676-687. [DOI: 10.1111/mmi.13908] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 01/02/2018] [Accepted: 01/03/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Alexander J. F. Egan
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences; Newcastle University, Baddiley-Clarke Building; Newcastle upon Tyne UK
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82
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Figueroa-Cuilan WM, Brown PJB. Cell Wall Biogenesis During Elongation and Division in the Plant Pathogen Agrobacterium tumefaciens. Curr Top Microbiol Immunol 2018; 418:87-110. [PMID: 29808336 DOI: 10.1007/82_2018_92] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
A great diversity of bacterial cell shapes can be found in nature, suggesting that cell wall biogenesis is regulated both spatially and temporally. Although Agrobacterium tumefaciens has a rod-shaped morphology, the mechanisms underlying cell growth are strikingly different than other well-studied rod-shaped bacteria including Escherichia coli. Technological advances, such as the ability to deplete essential genes and the development of fluorescent D-amino acids, have enabled recent advances in our understanding of cell wall biogenesis during cell elongation and division of A. tumefaciens. In this review, we address how the field has evolved over the years by providing a historical overview of cell elongation and division in rod-shaped bacteria. Next, we summarize the current understanding of cell growth and cell division processes in A. tumefaciens. Finally, we highlight the need for further research to answer key questions related to the regulation of cell wall biogenesis in A. tumefaciens.
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Affiliation(s)
| | - Pamela J B Brown
- Division of Biological Sciences, University of Missouri, Columbia, MO, USA.
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83
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Otten C, Brilli M, Vollmer W, Viollier PH, Salje J. Peptidoglycan in obligate intracellular bacteria. Mol Microbiol 2018; 107:142-163. [PMID: 29178391 PMCID: PMC5814848 DOI: 10.1111/mmi.13880] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2017] [Indexed: 01/08/2023]
Abstract
Peptidoglycan is the predominant stress-bearing structure in the cell envelope of most bacteria, and also a potent stimulator of the eukaryotic immune system. Obligate intracellular bacteria replicate exclusively within the interior of living cells, an osmotically protected niche. Under these conditions peptidoglycan is not necessarily needed to maintain the integrity of the bacterial cell. Moreover, the presence of peptidoglycan puts bacteria at risk of detection and destruction by host peptidoglycan recognition factors and downstream effectors. This has resulted in a selective pressure and opportunity to reduce the levels of peptidoglycan. In this review we have analysed the occurrence of genes involved in peptidoglycan metabolism across the major obligate intracellular bacterial species. From this comparative analysis, we have identified a group of predicted 'peptidoglycan-intermediate' organisms that includes the Chlamydiae, Orientia tsutsugamushi, Wolbachia and Anaplasma marginale. This grouping is likely to reflect biological differences in their infection cycle compared with peptidoglycan-negative obligate intracellular bacteria such as Ehrlichia and Anaplasma phagocytophilum, as well as obligate intracellular bacteria with classical peptidoglycan such as Coxiella, Buchnera and members of the Rickettsia genus. The signature gene set of the peptidoglycan-intermediate group reveals insights into minimal enzymatic requirements for building a peptidoglycan-like sacculus and/or division septum.
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Affiliation(s)
- Christian Otten
- The Centre for Bacterial Cell BiologyInstitute for Cell and Molecular Biosciences, Newcastle UniversityNewcastle upon TyneNE2 4AXUK
| | - Matteo Brilli
- Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE)University of Padova. Agripolis ‐ V.le dell'Università, 16 | 35020 Legnaro PadovaItaly
- Present address:
Department of BiosciencesUniversity of Milan, via Celoria 26(MI)Italy
| | - Waldemar Vollmer
- The Centre for Bacterial Cell BiologyInstitute for Cell and Molecular Biosciences, Newcastle UniversityNewcastle upon TyneNE2 4AXUK
| | - Patrick H. Viollier
- Department of Microbiology and Molecular MedicineInstitute of Genetics & Genomics in Geneva (iGE3), University of GenevaGenevaSwitzerland
| | - Jeanne Salje
- Nuffield Department of Medicine, Centre for Tropical Medicine and Global HealthUniversity of OxfordOxfordUK
- Mahidol‐Oxford Tropical Medicine Research UnitMahidol UniversityBangkokThailand
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84
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Pazos M, Otten C, Vollmer W. Bacterial Cell Wall Precursor Phosphatase Assays Using Thin-layer Chromatography (TLC) and High Pressure Liquid Chromatography (HPLC). Bio Protoc 2018; 8:e2761. [PMID: 29651453 DOI: 10.21769/bioprotoc.2761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Peptidoglycan encases the bacterial cytoplasmic membrane to protect the cell from lysis due to the turgor. The final steps of peptidoglycan synthesis require a membrane-anchored substrate called lipid II, in which the peptidoglycan subunit is linked to the carrier lipid undecaprenol via a pyrophosphate moiety. Lipid II is the target of glycopeptide antibiotics and several antimicrobial peptides, and is degraded by 'attacking' enzymes involved in bacterial competition to induce lysis. Here we describe two protocols using thin-layer chromatography (TLC) and high pressure liquid chromatography (HPLC), respectively, to assay the digestion of lipid II by phosphatases such as Colicin M or the LXG toxin protein TelC from Streptococcus intermedius. The TLC method can also monitor the digestion of undecaprenyl (pyro)phosphate, whereas the HPLC method allows to separate the di-, mono- or unphosphorylated disaccharide pentapeptide products of lipid II.
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Affiliation(s)
- Manuel Pazos
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK
| | - Christian Otten
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK
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85
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Radeck J, Lautenschläger N, Mascher T. The Essential UPP Phosphatase Pair BcrC and UppP Connects Cell Wall Homeostasis during Growth and Sporulation with Cell Envelope Stress Response in Bacillus subtilis. Front Microbiol 2017; 8:2403. [PMID: 29259598 PMCID: PMC5723303 DOI: 10.3389/fmicb.2017.02403] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 11/20/2017] [Indexed: 12/03/2022] Open
Abstract
The bacterial cell wall separates the cell from its surrounding and protects it from environmental stressors. Its integrity is maintained by a highly regulated process of cell wall biosynthesis. The membrane-located lipid II cycle provides cell wall building blocks that are assembled inside the cytoplasm to the outside for incorporation. Its carrier molecule, undecaprenyl phosphate (UP), is then recycled by dephosphorylation from undecaprenyl pyrophosphate (UPP). In Bacillus subtilis, this indispensable reaction is catalyzed by the UPP phosphatases BcrC and UppP. Here, we study the physiological function of both phosphatases with respect to morphology, cell wall homeostasis and the resulting cell envelope stress response (CESR). We demonstrate that uppP and bcrC represent a synthetic lethal gene pair, which encodes an essential physiological function. Accordingly, cell growth and morphology were severely impaired during exponential growth if the overall UPP phosphatase level was limiting. UppP, but not BcrC, was crucial for normal sporulation. Expression of bcrC, but not uppP, was upregulated in the presence of cell envelope stress conditions caused by bacitracin if UPP phosphatase levels were limited. This homeostatic feedback renders BcrC more important during growth than UppP, particularly in defense against cell envelope stress.
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Affiliation(s)
- Jara Radeck
- Institute of Microbiology, Technische Universität Dresden, Dresden, Germany
| | | | - Thorsten Mascher
- Institute of Microbiology, Technische Universität Dresden, Dresden, Germany
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86
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Hou Z, Shankar YV, Liu Y, Ding F, Subramanion JL, Ravikumar V, Zamudio-Vázquez R, Keogh D, Lim H, Tay MYF, Bhattacharjya S, Rice SA, Shi J, Duan H, Liu XW, Mu Y, Tan NS, Tam KC, Pethe K, Chan-Park MB. Nanoparticles of Short Cationic Peptidopolysaccharide Self-Assembled by Hydrogen Bonding with Antibacterial Effect against Multidrug-Resistant Bacteria. ACS APPLIED MATERIALS & INTERFACES 2017; 9:38288-38303. [PMID: 29028315 DOI: 10.1021/acsami.7b12120] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Cationic antimicrobial peptides (AMPs) and polymers are active against many multidrug-resistant (MDR) bacteria, but only a limited number of these compounds are in clinical use due to their unselective toxicity. The typical strategy for achieving selective antibacterial efficacy with low mammalian cell toxicity is through balancing the ratio of cationicity to hydrophobicity. Herein, we report a cationic nanoparticle self-assembled from chitosan-graft-oligolysine (CSM5-K5) chains with ultralow molecular weight (1450 Da) that selectively kills bacteria. Further, hydrogen bonding rather than the typical hydrophobic interaction causes the polymer chains to be aggregated together in water into small nanoparticles (with about 37 nm hydrodynamic radius) to concentrate the cationic charge of the lysine. When complexed with bacterial membrane, these cationic nanoparticles synergistically cluster anionic membrane lipids and produce a greater membrane perturbation and antibacterial effect than would be achievable by the same quantity of charge if dispersed in individual copolymer molecules in solution. The small zeta potential (+15 mV) and lack of hydrophobicity of the nanoparticles impedes the insertion of the copolymer into the cell bilayer to improve biocompatibility. In vivo study (using a murine excisional wound model) shows that CSM5-K5 suppresses the growth of methicillin-resistant Staphylococcus aureus (MRSA) bacteria by 4.0 orders of magnitude, an efficacy comparable to that of the last resort MRSA antibiotic vancomycin; it is also noninflammatory with little/no activation of neutrophils (CD11b and Ly6G immune cells). This study demonstrates a promising new class of cationic polymers-short cationic peptidopolysaccharides-that effectively attack MDR bacteria due to the synergistic clustering of, rather than insertion into, bacterial anionic lipids by the concentrated polymers in the resulting hydrogen-bonding-stabilized cationic nanoparticles.
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Affiliation(s)
| | | | - Yang Liu
- School of Biological Sciences, Nanyang Technological University , 62 Nanyang Drive, Singapore 637551, Singapore
| | | | | | - Vikashini Ravikumar
- Singapore Center for Environmental and Life Sciences (SCELSE) , 60 Nanyang Drive, Singapore 637551, Singapore
| | | | | | - Huiwen Lim
- Lee Kong Chian School of Medicine, Nanyang Technological University , 11 Mandalay Road, Singapore 308232, Singapore
| | - Moon Yue Feng Tay
- Nanyang Technological University Food Technology Centre (NAFTEC), Nanyang Technological University , 62 Nanyang Drive, Singapore 637459, Singapore
| | - Surajit Bhattacharjya
- School of Biological Sciences, Nanyang Technological University , 62 Nanyang Drive, Singapore 637551, Singapore
| | - Scott A Rice
- School of Biological Sciences, Nanyang Technological University , 62 Nanyang Drive, Singapore 637551, Singapore
- Singapore Center for Environmental and Life Sciences (SCELSE) , 60 Nanyang Drive, Singapore 637551, Singapore
| | - Jian Shi
- NUS Centre for Bioimaging Sciences, National University of Singapore , 14 Science Drive 4, Singapore 117557, Singapore
| | | | - Xue-Wei Liu
- Division of Chemistry and Biological Chemistry, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Yuguang Mu
- School of Biological Sciences, Nanyang Technological University , 62 Nanyang Drive, Singapore 637551, Singapore
| | - Nguan Soon Tan
- School of Biological Sciences, Nanyang Technological University , 62 Nanyang Drive, Singapore 637551, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University , 11 Mandalay Road, Singapore 308232, Singapore
| | - Kam C Tam
- Department of Chemical Engineering, Waterloo Institute for Nanotechnology, University of Waterloo , 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Kevin Pethe
- Lee Kong Chian School of Medicine, Nanyang Technological University , 11 Mandalay Road, Singapore 308232, Singapore
| | - Mary B Chan-Park
- School of Biological Sciences, Nanyang Technological University , 62 Nanyang Drive, Singapore 637551, Singapore
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87
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Zheng JJ, Perez AJ, Tsui HCT, Massidda O, Winkler ME. Absence of the KhpA and KhpB (JAG/EloR) RNA-binding proteins suppresses the requirement for PBP2b by overproduction of FtsA in Streptococcus pneumoniae D39. Mol Microbiol 2017; 106:793-814. [PMID: 28941257 DOI: 10.1111/mmi.13847] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2017] [Indexed: 12/11/2022]
Abstract
Suppressor mutations were isolated that obviate the requirement for essential PBP2b in peripheral elongation of peptidoglycan from the midcells of dividing Streptococcus pneumoniae D39 background cells. One suppressor was in a gene encoding a single KH-domain protein (KhpA). ΔkhpA suppresses deletions in most, but not all (mltG), genes involved in peripheral PG synthesis and in the gpsB regulatory gene. ΔkhpA mutations reduce growth rate, decrease cell size, minimally affect shape and induce expression of the WalRK cell-wall stress regulon. Reciprocal co-immunoprecipitations show that KhpA forms a complex in cells with another KH-domain protein (KhpB/JAG/EloR). ΔkhpA and ΔkhpB mutants phenocopy each other exactly, consistent with a direct interaction. RNA-immunoprecipitation showed that KhpA/KhpB bind an overlapping set of RNAs in cells. Phosphorylation of KhpB reported previously does not affect KhpB function in the D39 progenitor background. A chromosome duplication implicated FtsA overproduction in Δpbp2b suppression. We show that cellular FtsA concentration is negatively regulated by KhpA/B at the post-transcriptional level and that FtsA overproduction is necessary and sufficient for suppression of Δpbp2b. However, increased FtsA only partially accounts for the phenotypes of ΔkhpA mutants. Together, these results suggest that multimeric KhpA/B may function as a pleiotropic RNA chaperone controlling pneumococcal cell division.
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Affiliation(s)
- Jiaqi J Zheng
- Department of Biology, Indiana University Bloomington (IUB), Bloomington, IN 47405, USA
| | - Amilcar J Perez
- Department of Biology, Indiana University Bloomington (IUB), Bloomington, IN 47405, USA
| | - Ho-Ching Tiffany Tsui
- Department of Biology, Indiana University Bloomington (IUB), Bloomington, IN 47405, USA
| | - Orietta Massidda
- Dipartimento di Scienze Chirurgiche, Università di Cagliari, 09100 Cagliari, Italy
| | - Malcolm E Winkler
- Department of Biology, Indiana University Bloomington (IUB), Bloomington, IN 47405, USA
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88
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Bonnet J, Durmort C, Jacq M, Mortier-Barrière I, Campo N, VanNieuwenhze MS, Brun YV, Arthaud C, Gallet B, Moriscot C, Morlot C, Vernet T, Di Guilmi AM. Peptidoglycan O-acetylation is functionally related to cell wall biosynthesis and cell division in Streptococcus pneumoniae. Mol Microbiol 2017; 106:832-846. [PMID: 28960579 DOI: 10.1111/mmi.13849] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 09/11/2017] [Accepted: 09/23/2017] [Indexed: 12/12/2022]
Abstract
The peptidoglycan is a rigid matrix required to resist turgor pressure and to maintain the cellular shape. It is formed by linear glycan chains composed of N-acetylmuramic acid-(β-1,4)-N-acetylglucosamine (MurNAc-GlcNAc) disaccharides associated through cross-linked peptide stems. The peptidoglycan is continually remodelled by synthetic and hydrolytic enzymes and by chemical modifications, including O-acetylation of MurNAc residues that occurs in most Gram-positive and Gram-negative bacteria. This modification is a powerful strategy developed by pathogens to resist to lysozyme degradation and thus to escape from the host innate immune system but little is known about its physiological function. In this study, we have investigated to what extend peptidoglycan O-acetylation is involved in cell wall biosynthesis and cell division of Streptococcus pneumoniae. We show that O-acetylation driven by Adr protects the peptidoglycan of dividing cells from cleavage by the major autolysin LytA and occurs at the septal site. Our results support a function for Adr in the formation of robust and mature MurNAc O-acetylated peptidoglycan and infer its role in the division of the pneumococcus.
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Affiliation(s)
- Julie Bonnet
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
| | - Claire Durmort
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
| | - Maxime Jacq
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
| | - Isabelle Mortier-Barrière
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie intégrative (CBI). Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, UPS, F-31000 UMR Toulouse, France
| | - Nathalie Campo
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie intégrative (CBI). Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, UPS, F-31000 UMR Toulouse, France
| | | | - Yves V Brun
- Departments of Biology, Indiana University, Bloomington, IN, USA
| | - Christopher Arthaud
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
| | - Benoit Gallet
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
| | - Christine Moriscot
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
| | - Cécile Morlot
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
| | - Thierry Vernet
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
| | - Anne Marie Di Guilmi
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
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89
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PBP4 Mediates β-Lactam Resistance by Altered Function. Antimicrob Agents Chemother 2017; 61:AAC.00932-17. [PMID: 28807923 DOI: 10.1128/aac.00932-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 08/08/2017] [Indexed: 11/20/2022] Open
Abstract
Penicillin binding protein 4 (PBP4) can provide high-level β-lactam resistance in Staphylococcus aureus A series of missense and promoter mutations associated with pbp4 were detected in strains that displayed high-level resistance. We show here that the missense mutations facilitate the β-lactam resistance mediated by PBP4 and the promoter mutations lead to overexpression of pbp4 Our results also suggest a cooperative interplay among PBPs for β-lactam resistance.
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90
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Caccamo PD, Brun YV. The Molecular Basis of Noncanonical Bacterial Morphology. Trends Microbiol 2017; 26:191-208. [PMID: 29056293 DOI: 10.1016/j.tim.2017.09.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 09/08/2017] [Accepted: 09/28/2017] [Indexed: 01/04/2023]
Abstract
Bacteria come in a wide variety of shapes and sizes. The true picture of bacterial morphological diversity is likely skewed due to an experimental focus on pathogens and industrially relevant organisms. Indeed, most of the work elucidating the genes and molecular processes involved in maintaining bacterial morphology has been limited to rod- or coccal-shaped model systems. The mechanisms of shape evolution, the molecular processes underlying diverse shapes and growth modes, and how individual cells can dynamically modulate their shape are just beginning to be revealed. Here we discuss recent work aimed at advancing our knowledge of shape diversity and uncovering the molecular basis for shape generation in noncanonical and morphologically complex bacteria.
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Affiliation(s)
- Paul D Caccamo
- Department of Biology, Indiana University, 1001 E. 3rd St, Bloomington, IN 47405, USA
| | - Yves V Brun
- Department of Biology, Indiana University, 1001 E. 3rd St, Bloomington, IN 47405, USA.
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91
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Meiresonne NY, van der Ploeg R, Hink MA, den Blaauwen T. Activity-Related Conformational Changes in d,d-Carboxypeptidases Revealed by In Vivo Periplasmic Förster Resonance Energy Transfer Assay in Escherichia coli. mBio 2017; 8:e01089-17. [PMID: 28900026 PMCID: PMC5596342 DOI: 10.1128/mbio.01089-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 08/04/2017] [Indexed: 11/20/2022] Open
Abstract
One of the mechanisms of β-lactam antibiotic resistance requires the activity of d,d-carboxypeptidases (d,d-CPases) involved in peptidoglycan (PG) synthesis, making them putative targets for new antibiotic development. The activity of PG-synthesizing enzymes is often correlated with their association with other proteins. The PG layer is maintained in the periplasm between the two membranes of the Gram-negative cell envelope. Because no methods existed to detect in vivo interactions in this compartment, we have developed and validated a Förster resonance energy transfer assay. Using the fluorescent-protein donor-acceptor pair mNeonGreen-mCherry, periplasmic protein interactions were detected in fixed and in living bacteria, in single samples or in plate reader 96-well format. We show that the d,d-CPases PBP5, PBP6a, and PBP6b of Escherichia coli change dimer conformation between resting and active states. Complementation studies and changes in localization suggest that these d,d-CPases are not redundant but that their balanced activity is required for robust PG synthesis.IMPORTANCE The periplasmic space between the outer and the inner membrane of Gram-negative bacteria contains many essential regulatory, transport, and cell wall-synthesizing and -hydrolyzing proteins. To date, no assay is available to determine protein interactions in this compartment. We have developed a periplasmic protein interaction assay for living and fixed bacteria in single samples or 96-well-plate format. Using this assay, we were able to demonstrate conformation changes related to the activity of proteins that could not have been detected by any other living-cell method available. The assay uniquely expands our toolbox for antibiotic screening and mode-of-action studies.
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Affiliation(s)
- Nils Y Meiresonne
- Bacterial Cell Biology and Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - René van der Ploeg
- Bacterial Cell Biology and Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Mark A Hink
- Molecular Cytology and van Leeuwenhoek Centre for Advanced Microscopy, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Tanneke den Blaauwen
- Bacterial Cell Biology and Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
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92
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Abstract
The innate immune system serves as a first line of defense against microbial pathogens. The host innate immune response can be triggered by recognition of conserved non-self-microbial signature molecules by specific host receptor proteins called Toll-like receptors. For bacteria, many of these molecular triggers reside on or are embedded in the bacterial membrane, the interface exposed to the host environment. Lipids are the most abundant component of membranes, and bacteria possess a unique set of lipids that can initiate or modify the host innate immune response. Bacterial lipoproteins, peptidoglycan, and outer membrane molecules lipoteichoic acid and lipopolysaccharide are key modulators of the host immune system. This review article will highlight some of the research emerging at the crossroads of bacterial membranes and innate immunity.
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Affiliation(s)
- Courtney E Chandler
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, 650 W. Baltimore Street, 8th Floor South, Baltimore, MD, 21201, USA
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, 650 W. Baltimore Street, 8th Floor South, Baltimore, MD, 21201, USA
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93
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Robust peptidoglycan growth by dynamic and variable multi-protein complexes. Curr Opin Microbiol 2017; 36:55-61. [DOI: 10.1016/j.mib.2017.01.006] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 01/14/2017] [Accepted: 01/19/2017] [Indexed: 11/19/2022]
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94
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PBP1B Glycosyltransferase and Transpeptidase Activities Play Different Essential Roles during the De Novo Regeneration of Rod Morphology in Escherichia coli. J Bacteriol 2017; 199:JB.00612-16. [PMID: 28096447 DOI: 10.1128/jb.00612-16] [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: 08/30/2016] [Accepted: 01/10/2017] [Indexed: 11/20/2022] Open
Abstract
Peptidoglycan is a vital component of nearly all cell wall-bearing bacteria and is a valuable target for antibacterial therapy. However, despite decades of work, there remain important gaps in understanding how this macromolecule is synthesized and molded into a three-dimensional structure that imparts specific morphologies to individual cells. Here, we investigated the particularly enigmatic area of how peptidoglycan is synthesized and shaped during the first stages of creating cell shape de novo, that is, in the absence of a preexisting template. We found that when lysozyme-induced (LI) spheroplasts of Escherichia coli were allowed to resynthesize peptidoglycan, the cells divided first and then elongated to recreate a normal rod-shaped morphology. Penicillin binding protein 1B (PBP1B) was critical for the first stage of this recovery process. PBP1B synthesized peptidoglycan de novo, and this synthesis required that PBP1B interact with the outer membrane lipoprotein LpoB. Surprisingly, when LpoB was localized improperly to the inner membrane, recovering spheroplasts synthesized peptidoglycan and divided but then propagated as amorphous spheroidal cells, suggesting that the regeneration of a normal rod shape depends on a particular spatial interaction. Similarly, spheroplasts carrying a PBP1B variant lacking transpeptidase activity or those in which PBP1A was overproduced could synthesize new peptidoglycan and divide but then grew as oddly shaped spheroids. We conclude that de novo cell wall synthesis requires the glycosyltransferase activity of PBP1B but that PBP1B transpeptidase activity is needed to assemble cell walls with wild-type morphology.IMPORTANCE Bacterial cell wall peptidoglycan is synthesized and modified by penicillin binding proteins (PBPs), which are targeted by about half of all currently prescribed antibiotics, including penicillin and its derivatives. Because antibiotic resistance is rising, it has become increasingly urgent that we fill the gaps in our knowledge about how PBPs create and assemble this protective wall. We report here that PBP1B plays an essential role in synthesizing peptidoglycan in the absence of a preexisting template: its glycosyltransferase activity is responsible for de novo synthesis, while its transpeptidase activity is required to construct cell walls of a specific shape. These results highlight the importance of this enzyme and distinguish its biological roles from those of other PBPs and peptidoglycan synthases.
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95
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Egan AJF, Cleverley RM, Peters K, Lewis RJ, Vollmer W. Regulation of bacterial cell wall growth. FEBS J 2017; 284:851-867. [PMID: 27862967 DOI: 10.1111/febs.13959] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 10/28/2016] [Accepted: 11/09/2016] [Indexed: 12/19/2022]
Abstract
During growth and propagation, a bacterial cell enlarges and subsequently divides its peptidoglycan (PG) sacculus, a continuous mesh-like layer that encases the cell membrane to confer mechanical strength and morphological robustness. The mechanism of sacculus growth, how it is regulated and how it is coordinated with other cellular processes is poorly understood. In this article, we will discuss briefly the current knowledge of how cell wall synthesis is regulated, on multiple levels, from both sides of the cytoplasmic membrane. According to the current knowledge, cytosolic scaffolding proteins connect PG synthases with cytoskeletal elements, and protein phosphorylation regulates cell wall growth in Gram-positive species. PG-active enzymes engage in multiple protein-protein interactions within PG synthesis multienzyme complexes, and some of the interactions modulate activities. PG synthesis is also regulated by central metabolism, and by PG maturation through the action of PG hydrolytic enzymes. Only now are we beginning to appreciate how these multiple levels of regulating PG synthesis enable the cell to propagate robustly with a defined cell shape under different and variable growth conditions.
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Affiliation(s)
- Alexander J F Egan
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne, UK
| | - Robert M Cleverley
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne, UK
| | - Katharina Peters
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne, UK
| | - Richard J Lewis
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne, UK
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne, UK
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96
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Interplay between Penicillin-binding proteins and SEDS proteins promotes bacterial cell wall synthesis. Sci Rep 2017; 7:43306. [PMID: 28233869 PMCID: PMC5324115 DOI: 10.1038/srep43306] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 01/06/2017] [Indexed: 11/14/2022] Open
Abstract
Bacteria utilize specialized multi-protein machineries to synthesize the essential peptidoglycan (PG) cell wall during growth and division. The divisome controls septal PG synthesis and separation of daughter cells. In E. coli, the lipid II transporter candidate FtsW is thought to work in concert with the PG synthases penicillin-binding proteins PBP3 and PBP1b. Yet, the exact molecular mechanisms of their function in complexes are largely unknown. We show that FtsW interacts with PBP1b and lipid II and that PBP1b, FtsW and PBP3 co-purify suggesting that they form a trimeric complex. We also show that the large loop between transmembrane helices 7 and 8 of FtsW is important for the interaction with PBP3. Moreover, we found that FtsW, but not the other flippase candidate MurJ, impairs lipid II polymerization and peptide cross-linking activities of PBP1b, and that PBP3 relieves these inhibitory effects. All together the results suggest that FtsW interacts with lipid II preventing its polymerization by PBP1b unless PBP3 is also present, indicating that PBP3 facilitates lipid II release and/or its transfer to PBP1b after transport across the cytoplasmic membrane. This tight regulatory mechanism is consistent with the cell’s need to ensure appropriate use of the limited pool of lipid II.
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97
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Vega-Cabrera LA, Pardo-López L. Membrane remodeling and organization: Elements common to prokaryotes and eukaryotes. IUBMB Life 2017; 69:55-62. [DOI: 10.1002/iub.1604] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 12/15/2016] [Indexed: 01/14/2023]
Affiliation(s)
- Luz A. Vega-Cabrera
- Instituto de Biotecnología, Universidad Nacional Autónoma de México; Apdo. Postal 510-3 Cuernavaca Morelos México
| | - Liliana Pardo-López
- Instituto de Biotecnología, Universidad Nacional Autónoma de México; Apdo. Postal 510-3 Cuernavaca Morelos México
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98
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Abstract
As discovered over the past 25 years, the cytoskeletons of bacteria and archaea are complex systems of proteins whose central components are dynamic cytomotive filaments. They perform roles in cell division, DNA partitioning, cell shape determination and the organisation of intracellular components. The protofilament structures and polymerisation activities of various actin-like, tubulin-like and ESCRT-like proteins of prokaryotes closely resemble their eukaryotic counterparts but show greater diversity. Their activities are modulated by a wide range of accessory proteins but these do not include homologues of the motor proteins that supplement filament dynamics to aid eukaryotic cell motility. Numerous other filamentous proteins, some related to eukaryotic IF-proteins/lamins and dynamins etc, seem to perform structural roles similar to those in eukaryotes.
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Affiliation(s)
- Linda A Amos
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
| | - Jan Löwe
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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99
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Abstract
Cytokinesis in E. coli is organized by a cytoskeletal element designated the Z ring. The Z ring is formed at midcell by the coalescence of FtsZ filaments tethered to the membrane by interaction of FtsZ's conserved C-terminal peptide (CCTP) with two membrane-associated proteins, FtsA and ZipA. Although interaction between an FtsZ monomer and either of these proteins is of low affinity, high affinity is achieved through avidity - polymerization linked CCTPs interacting with the membrane tethers. The placement of the Z ring at midcell is ensured by antagonists of FtsZ polymerization that are positioned within the cell and target FtsZ filaments through the CCTP. The placement of the ring is reinforced by a protein network that extends from the terminus (Ter) region of the chromosome to the Z ring. Once the Z ring is established, additional proteins are recruited through interaction with FtsA, to form the divisome. The assembled divisome is then activated by FtsN to carry out septal peptidoglycan synthesis, with a dynamic Z ring serving as a guide for septum formation. As the septum forms, the cell wall is split by spatially regulated hydrolases and the outer membrane invaginates in step with the aid of a transenvelope complex to yield progeny cells.
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Affiliation(s)
- Joe Lutkenhaus
- University of Kansas Medical Center, Kansas City, KS, USA.
| | - Shishen Du
- University of Kansas Medical Center, Kansas City, KS, USA
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100
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van't Veer IL, Leloup NOL, Egan AJF, Janssen BJC, Martin NI, Vollmer W, Breukink E. Site-Specific Immobilization of the Peptidoglycan Synthase PBP1B on a Surface Plasmon Resonance Chip Surface. Chembiochem 2016; 17:2250-2256. [PMID: 27709766 PMCID: PMC5298014 DOI: 10.1002/cbic.201600461] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Indexed: 12/23/2022]
Abstract
Surface plasmon resonance (SPR) is one of the most powerful label-free methods to determine the kinetic parameters of molecular interactions in real time and in a highly sensitive way. Penicillin-binding proteins (PBPs) are peptidoglycan synthesis enzymes present in most bacteria. Established protocols to analyze interactions of PBPs by SPR involve immobilization to an ampicillin-coated chip surface (a β-lactam antibiotic mimicking its substrate), thereby forming a covalent complex with the PBPs transpeptidase (TP) active site. However, PBP interactions measured with a substrate-bound TP domain potentially affect interactions near the TPase active site. Furthermore, in vivo PBPs are anchored in the inner membrane by an N-terminal transmembrane helix, and hence immobilization at the C-terminal TPase domain gives an orientation contrary to the in vivo situation. We designed a new procedure: immobilization of PBP by copper-free click chemistry at an azide incorporated in the N terminus. In a proof-of-principle study, we immobilized Escherichia coli PBP1B on an SPR chip surface and used this for the analysis of the well-characterized interaction of PBP1B with LpoB. The site-specific incorporation of the azide affords control over protein orientation, thereby resulting in a homogeneous immobilization on the chip surface. This method can be used to study topology-dependent interactions of any (membrane) protein.
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Affiliation(s)
- Inge L. van't Veer
- Department of Membrane Biochemistry and BiophysicsUtrecht UniversityPadualaan 83584 CHUtrechtThe Netherlands
| | - Nadia O. L. Leloup
- Crystal and Structural ChemistryUtrecht UniversityPadualaan 83584 CHUtrechtThe Netherlands
| | - Alexander J. F. Egan
- The Centre for Bacterial Cell BiologyNewcastle UniversityRichardson RoadNE2 4AX, Newcastle upon TyneUK
| | - Bert J. C. Janssen
- Crystal and Structural ChemistryUtrecht UniversityPadualaan 83584 CHUtrechtThe Netherlands
| | - Nathaniel I. Martin
- Department of Chemical Biology and Drug DiscoveryUtrecht Institute for Pharmaceutical SciencesUtrecht UniversityUniversiteitsweg 993584 CGUtrechtThe Netherlands
| | - Waldemar Vollmer
- The Centre for Bacterial Cell BiologyNewcastle UniversityRichardson RoadNE2 4AX, Newcastle upon TyneUK
| | - Eefjan Breukink
- Department of Membrane Biochemistry and BiophysicsUtrecht UniversityPadualaan 83584 CHUtrechtThe Netherlands
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