1
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Middlemiss S, Blandenet M, Roberts DM, McMahon A, Grimshaw J, Edwards JM, Sun Z, Whitley KD, Blu T, Strahl H, Holden S. Molecular motor tug-of-war regulates elongasome cell wall synthesis dynamics in Bacillus subtilis. Nat Commun 2024; 15:5411. [PMID: 38926336 PMCID: PMC11208587 DOI: 10.1038/s41467-024-49785-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 06/18/2024] [Indexed: 06/28/2024] Open
Abstract
Most rod-shaped bacteria elongate by inserting new cell wall material into the inner surface of the cell sidewall. This is performed by class A penicillin binding proteins (PBPs) and a highly conserved protein complex, the elongasome, which moves processively around the cell circumference and inserts long glycan strands that act as barrel-hoop-like reinforcing structures, thereby giving rise to a rod-shaped cell. However, it remains unclear how elongasome synthesis dynamics and termination events are regulated to determine the length of these critical cell-reinforcing structures. To address this, we developed a method to track individual elongasome complexes around the entire circumference of Bacillus subtilis cells for minutes-long periods using single-molecule fluorescence microscopy. We found that the B. subtilis elongasome is highly processive and that processive synthesis events are frequently terminated by rapid reversal or extended pauses. We found that cellular levels of RodA regulate elongasome processivity, reversal and pausing. Our single-molecule data, together with stochastic simulations, show that elongasome dynamics and processivity are regulated by molecular motor tug-of-war competition between several, likely two, oppositely oriented peptidoglycan synthesis complexes associated with the MreB filament. Altogether these results demonstrate that molecular motor tug-of-war is a key regulator of elongasome dynamics in B. subtilis, which likely also regulates the cell shape via modulation of elongasome processivity.
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Affiliation(s)
- Stuart Middlemiss
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
| | - Matthieu Blandenet
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - David M Roberts
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, UK
| | - Andrew McMahon
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, UK
| | - James Grimshaw
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Joshua M Edwards
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, UK
| | - Zikai Sun
- Department of Electronic Engineering, The Chinese University of Hong Kong, Hong Kong, China
| | - Kevin D Whitley
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Thierry Blu
- Department of Electronic Engineering, The Chinese University of Hong Kong, Hong Kong, China
- Dept of Electrical Engineering, National Taiwan University, Taipei City, Taiwan
| | - Henrik Strahl
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
| | - Séamus Holden
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, UK.
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2
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Perez AJ, Lamanna MM, Bruce KE, Touraev MA, Page JE, Shaw SL, Tsui HCT, Winkler ME. Elongasome core proteins and class A PBP1a display zonal, processive movement at the midcell of Streptococcus pneumoniae. Proc Natl Acad Sci U S A 2024; 121:e2401831121. [PMID: 38875147 PMCID: PMC11194595 DOI: 10.1073/pnas.2401831121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 05/02/2024] [Indexed: 06/16/2024] Open
Abstract
Ovoid-shaped bacteria, such as Streptococcus pneumoniae (pneumococcus), have two spatially separated peptidoglycan (PG) synthase nanomachines that locate zonally to the midcell of dividing cells. The septal PG synthase bPBP2x:FtsW closes the septum of dividing pneumococcal cells, whereas the elongasome located on the outer edge of the septal annulus synthesizes peripheral PG outward. We showed previously by sm-TIRFm that the septal PG synthase moves circumferentially at midcell, driven by PG synthesis and not by FtsZ treadmilling. The pneumococcal elongasome consists of the PG synthase bPBP2b:RodA, regulators MreC, MreD, and RodZ, but not MreB, and genetically associated proteins Class A aPBP1a and muramidase MpgA. Given its zonal location separate from FtsZ, it was of considerable interest to determine the dynamics of proteins in the pneumococcal elongasome. We found that bPBP2b, RodA, and MreC move circumferentially with the same velocities and durations at midcell, driven by PG synthesis. However, outside of the midcell zone, the majority of these elongasome proteins move diffusively over the entire surface of cells. Depletion of MreC resulted in loss of circumferential movement of bPBP2b, and bPBP2b and RodA require each other for localization and circumferential movement. Notably, a fraction of aPBP1a molecules also moved circumferentially at midcell with velocities similar to those of components of the core elongasome, but for shorter durations. Other aPBP1a molecules were static at midcell or diffusing over cell bodies. Last, MpgA displayed nonprocessive, subdiffusive motion that was largely confined to the midcell region and less frequently detected over the cell body.
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Affiliation(s)
- Amilcar J. Perez
- Department of Biology, Indiana University Bloomington, Bloomington, IN47405
| | - Melissa M. Lamanna
- Department of Biology, Indiana University Bloomington, Bloomington, IN47405
| | - Kevin E. Bruce
- Department of Biology, Indiana University Bloomington, Bloomington, IN47405
| | - Marc A. Touraev
- Department of Biology, Indiana University Bloomington, Bloomington, IN47405
| | - Julia E. Page
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA02115
| | - Sidney L. Shaw
- Department of Biology, Indiana University Bloomington, Bloomington, IN47405
| | | | - Malcolm E. Winkler
- Department of Biology, Indiana University Bloomington, Bloomington, IN47405
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3
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Hu M, Dong J, Wang H, Huang J, Geng L, Liu M, Tao C, Liu J, Chen X, Ahmed MBM, Zhao W, Sun X, Guo Y. Novel ratiometric electrochemical aptasensor based on broad-spectrum aptamer recognition for simultaneous detection of penicillin antibiotics in milk. Food Chem 2024; 456:139946. [PMID: 38852450 DOI: 10.1016/j.foodchem.2024.139946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 05/30/2024] [Accepted: 05/31/2024] [Indexed: 06/11/2024]
Abstract
To effectively monitor multi-residues of penicillin antibiotics (PENs) in milk, we developed a novel ratiometric electrochemical aptasensor enabling simultaneous detection of PENs. The aptasensor employed a broad-spectrum aptamer as a recognition element, niobium carbide functionalized with methylene blue (Nb2C-MB) as a reference signal generator, and a ferrocene-labeled aptamer (Fc-Apt) as an output signal. Electrodes were modified with Fe-N-C doped carbon nanotubes (Fe-N-C-CNTs) to amplify detection signals further. During detection, Fc-Apt binding to PENs decreased Fc current intensity (IFc) and increased MB current intensity (IMB). The simultaneous detection of PENs was achieved using IMB/IFc as a quantitative signal. Under optimal conditions, a good linear relationship between IMB/IFc and antibiotic concentration was observed, indicating the aptasensor had a robustness. The limits of detection of aptasensor for four penicillin antibiotics and their mixed targets were 0.093-0.191 nM. This work provides a new approach to multi-residue detection of the same class of antibiotics.
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Affiliation(s)
- Mengjiao Hu
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Jiwei Dong
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Haifang Wang
- Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing 100700, China
| | - Jingcheng Huang
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Lingjun Geng
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Mengyue Liu
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Chong Tao
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Jingjing Liu
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Xiaofeng Chen
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | | | - Wenping Zhao
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Xia Sun
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China.
| | - Yemin Guo
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China.
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4
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Perez AJ, Xiao J. Stay on track - revelations of bacterial cell wall synthesis enzymes and things that go by single-molecule imaging. Curr Opin Microbiol 2024; 79:102490. [PMID: 38821027 PMCID: PMC11162910 DOI: 10.1016/j.mib.2024.102490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 05/08/2024] [Accepted: 05/09/2024] [Indexed: 06/02/2024]
Abstract
In this review, we explore the regulation of septal peptidoglycan (sPG) synthesis in bacterial cell division, a critical process for cell viability and proper morphology. Recent single-molecule imaging studies have revealed the processive movement of the FtsW:bPBP synthase complex along the septum, shedding light on the spatiotemporal dynamics of sPG synthases and their regulators. In diderm bacteria (E. coli and C. crescentus), the movement occurs at two distinct speeds, reflecting active synthesis or inactivity driven by FtsZ-treadmilling. In monoderm bacteria (B. subtilis, S. pneumoniae, and S. aureus), however, these enzymes exhibit only the active sPG-track-coupled processive movement. By comparing the dynamics of sPG synthases in these organisms and that of class-A penicillin-binding proteins in vivo and in vitro, we propose a unifying model for septal cell wall synthesis regulation across species, highlighting the roles of the sPG- and Z-tracks in orchestrating a robust bacterial cell wall constriction process.
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Affiliation(s)
- Amilcar J Perez
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jie Xiao
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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5
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Biba DA, Wolf YI, Koonin EV, Rochman ND. Balance between asymmetric allocation and repair of somatic damage in unicellular life forms as an ancient form of r/K selection. Proc Natl Acad Sci U S A 2024; 121:e2400008121. [PMID: 38787879 PMCID: PMC11145259 DOI: 10.1073/pnas.2400008121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Accepted: 04/24/2024] [Indexed: 05/26/2024] Open
Abstract
Over the course of multiple divisions, cells accumulate diverse nongenetic, somatic damage including misfolded and aggregated proteins and cell wall defects. If the rate of damage accumulation exceeds the rate of dilution through cell growth, a dedicated mitigation strategy is required to prevent eventual population collapse. Strategies for somatic damage control can be divided into two categories, asymmetric allocation and repair, which are not, in principle, mutually exclusive. We explore a mathematical model to identify the optimal strategy, maximizing the total cell number, over a wide range of environmental and physiological conditions. The optimal strategy is primarily determined by extrinsic, damage-independent mortality and the physiological model for damage accumulation that can be either independent (linear) or increasing (exponential) with respect to the prior accumulated damage. Under the linear regime, the optimal strategy is either exclusively repair or asymmetric allocation, whereas under the exponential regime, the optimal strategy is a combination of asymmetry and repair. Repair is preferred when extrinsic mortality is low, whereas at high extrinsic mortality, asymmetric damage allocation becomes the strategy of choice. We hypothesize that at an early stage of life evolution, optimization over repair and asymmetric allocation of somatic damage gave rise to r and K selection strategists.
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Affiliation(s)
- Dmitry A. Biba
- National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, MD20894
- Oak Ridge Institute for Science and Education, Oak Ridge, TN37830
| | - Yuri I. Wolf
- National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, MD20894
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, MD20894
| | - Nash D. Rochman
- National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, MD20894
- Institute for Implementation Science in Population Health, City University of New York, New York, NY10027
- Department of Epidemiology and Biostatistics, Graduate School of Public Health and Health Policy City, University of New York, New York, NY10027
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6
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Rajguru V, Chatterjee S, Garde S, Reddy M. Crosslink cleaving enzymes: the smart autolysins that remodel the bacterial cell wall. Trends Microbiol 2024; 32:494-506. [PMID: 38072724 DOI: 10.1016/j.tim.2023.11.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 11/13/2023] [Accepted: 11/13/2023] [Indexed: 05/12/2024]
Abstract
Peptidoglycan (PG) is a protective mesh-like polymer in bacterial cell walls that enables their survival in almost every ecological niche. PG is formed by crosslinking of several glycan strands through short peptides, conferring a characteristic structure and elasticity, distinguishing it from other polymeric exoskeletons. The significance of PG crosslink formation has been known for decades, as some of the most widely used antibiotics, namely β-lactams, target the enzymes that catalyze this step. However, the importance of crosslink hydrolysis in PG biology remained largely underappreciated. Recent advances demonstrate the functions of crosslink cleavage in diverse physiological processes, including an indispensable role in PG expansion during the cell cycle, thereby making crosslink cleaving enzymes an untapped target for novel drugs. Here, we elaborate on the fundamental roles of crosslink-specific endopeptidases and their regulation across the bacterial kingdom.
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Affiliation(s)
- Vaidehi Rajguru
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, 500007, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Stuti Chatterjee
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, 500007, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Shambhavi Garde
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, 500007, India
| | - Manjula Reddy
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, 500007, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
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7
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Perez AJ, Lamanna MM, Bruce KE, Touraev MA, Page JE, Shaw SL, Tsui HCT, Winkler ME. Elongasome core proteins and class A PBP1a display zonal, processive movement at the midcell of Streptococcus pneumoniae. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.10.575112. [PMID: 38328058 PMCID: PMC10849506 DOI: 10.1101/2024.01.10.575112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Ovoid-shaped bacteria, such as Streptococcus pneumoniae (pneumococcus), have two spatially separated peptidoglycan (PG) synthase nanomachines that locate zonally to the midcell of dividing cells. The septal PG synthase bPBP2x:FtsW closes the septum of dividing pneumococcal cells, whereas the elongasome located on the outer edge of the septal annulus synthesizes peripheral PG outward. We showed previously by sm-TIRFm that the septal PG synthase moves circumferentially at midcell, driven by PG synthesis and not by FtsZ treadmilling. The pneumococcal elongasome consists of the PG synthase bPBP2b:RodA, regulators MreC, MreD, and RodZ, but not MreB, and genetically associated proteins Class A aPBP1a and muramidase MpgA. Given its zonal location separate from FtsZ, it was of considerable interest to determine the dynamics of proteins in the pneumococcal elongasome. We found that bPBP2b, RodA, and MreC move circumferentially with the same velocities and durations at midcell, driven by PG synthesis. However, outside of the midcell zone, the majority of these elongasome proteins move diffusively over the entire surface of cells. Depletion of MreC resulted in loss of circumferential movement of bPBP2b, and bPBP2b and RodA require each other for localization and circumferential movement. Notably, a fraction of aPBP1a molecules also moved circumferentially at midcell with velocities similar to those of components of the core elongasome, but for shorter durations. Other aPBP1a molecules were static at midcell or diffusing over cell bodies. Last, MpgA displayed non-processive, subdiffusive motion that was largely confined to the midcell region and less frequently detected over the cell body.
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8
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Hu M, Yue F, Dong J, Tao C, Bai M, Liu M, Zhai S, Chen S, Liu W, Qi G, Vrublevsky I, Sun X, Guo Y. Screening of broad-spectrum aptamer and development of electrochemical aptasensor for simultaneous detection of penicillin antibiotics in milk. Talanta 2024; 269:125508. [PMID: 38070284 DOI: 10.1016/j.talanta.2023.125508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 11/29/2023] [Accepted: 11/30/2023] [Indexed: 01/05/2024]
Abstract
Penicillin antibiotics (PENs) play an important role in killing pathogenic bacteria. However, the residues of various penicillin antibiotics in milk gradually accumulate in the human body with the increase of milk intake, which causes direct harm to the human body. Aptamers can be used as recognition element of sensors. It is great significance to use broad-spectrum aptamers for simultaneous detection of PENs. In this study, we reported the screening and identification of DNA aptamers for PENs. The aptamers were screened by graphene oxide-systematic evolution of ligands by exponential enrichment (GO-SELEX). The broad-spectrum aptamers with high affinity and specificity were successfully obtained after 13 rounds of screening. The affinity and specificity of candidate aptamers were analyzed by a GO fluorescence competition method. Further sequence analysis revealed that a truncated 47 nt aptamer (P-11-1) had a higher affinity than the original 79 nt aptamer. The truncated aptamer P-11-1 was used as a recognition element, and an electrochemical aptasensor was prepared using gold nanoparticles (AuNPs) combined with ferroferric oxide-multi walled carbon nanotube (Fe3O4-MWCNTs) complex. The results showed that the developed aptasensor achieved the simultaneous detection of PENs in milk samples across a concentration range of 2 nM-10,000 nM, achieving a limit of detection of 0.667 nM. This methodology provided a simple and sensitive new thinking for antibiotic multi-residue detection.
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Affiliation(s)
- Mengjiao Hu
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Fengling Yue
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Jiwei Dong
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Chong Tao
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Mengyuan Bai
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Mengyue Liu
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Shengxi Zhai
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Shihao Chen
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Wenzheng Liu
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Guangyu Qi
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China
| | - Igor Vrublevsky
- Department of Information Security, Belarusian State University of Informatics and Radioelectronics, Minsk 220013, Belarus
| | - Xia Sun
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China.
| | - Yemin Guo
- College of Agricultural Engineering and Food Science, Shandong University of Technology, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Shandong Provincial Engineering Research Center of Vegetable Safety and Quality Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China; Zibo City Key Laboratory of Agricultural Product Safety Traceability, No. 266 Xincun Xilu, Zibo, Shandong 255049, China.
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9
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Cheng T, Boneca IG. The shapeshifting Helicobacter pylori: From a corkscrew to a ball. Mol Microbiol 2024; 121:260-274. [PMID: 38173305 DOI: 10.1111/mmi.15218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 12/08/2023] [Accepted: 12/17/2023] [Indexed: 01/05/2024]
Abstract
There is growing evidence that bacterial morphology is closely related to their lifestyle. The helical Helicobacter pylori relies on its unique shape for survival and efficient colonization of the human stomach. Yet, they have been observed to transform into another distinctive morphology, the spherical coccoid. Despite being hypothesized to be involved in the persistence and transmission of this species, years of effort in deciphering the roles of the coccoid form remain fruitless since contrasting observations regarding its lifestyle were reported. Here, we discuss the two forms of H. pylori with a focus on the coccoid form, the molecular mechanism behind its morphological transformation, and experimental approaches to further develop our understanding of this phenomenon. We also propose a putative mechanism of the coccoid formation in H. pylori through induction of a type-I toxin-antitoxin (TA) system recently shown to influence the morphology of this species.
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Affiliation(s)
- Thimoro Cheng
- Institut Pasteur, Université Paris Cité, Unité Biologie et génétique de la paroi bactérienne, Paris, France
| | - Ivo Gomperts Boneca
- Institut Pasteur, Université Paris Cité, Unité Biologie et génétique de la paroi bactérienne, Paris, France
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10
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Shrestha S, Taib N, Gribaldo S, Shen A. Diversification of division mechanisms in endospore-forming bacteria revealed by analyses of peptidoglycan synthesis in Clostridioides difficile. Nat Commun 2023; 14:7975. [PMID: 38042849 PMCID: PMC10693644 DOI: 10.1038/s41467-023-43595-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 11/14/2023] [Indexed: 12/04/2023] Open
Abstract
The bacterial enzymes FtsW and FtsI, encoded in the highly conserved dcw gene cluster, are considered to be universally essential for the synthesis of septal peptidoglycan (PG) during cell division. Here, we show that the pathogen Clostridioides difficile lacks a canonical FtsW/FtsI pair, and its dcw-encoded PG synthases have undergone a specialization to fulfill sporulation-specific roles, including synthesizing septal PG during the sporulation-specific mode of cell division. Although these enzymes are directly regulated by canonical divisome components during this process, dcw-encoded PG synthases and their divisome regulators are dispensable for cell division during normal growth. Instead, C. difficile uses a bifunctional class A penicillin-binding protein as the core divisome PG synthase, revealing a previously unreported role for this class of enzymes. Our findings support that the emergence of endosporulation in the Firmicutes phylum facilitated the functional repurposing of cell division factors. Moreover, they indicate that C. difficile, and likely other clostridia, assemble a distinct divisome that therefore may represent a unique target for therapeutic interventions.
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Affiliation(s)
- Shailab Shrestha
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
- Program in Molecular Microbiology, Tufts University Graduate School of Biomedical Sciences, Boston, MA, USA
| | - Najwa Taib
- Institut Pasteur, Université Paris Cité, Evolutionary Biology of the Microbial Cell Unit, Paris, France
- Institut Pasteur, Université Paris Cité, Bioinformatics and Biostatistics Hub, F-75015, Paris, France
| | - Simonetta Gribaldo
- Institut Pasteur, Université Paris Cité, Evolutionary Biology of the Microbial Cell Unit, Paris, France
| | - Aimee Shen
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA.
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11
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Biba DA, Wolf YI, Koonin EV, Rochman ND. Unicellular life balances asymmetric allocation and repair of somatic damage representing the origin of r/K selection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.21.568103. [PMID: 38076808 PMCID: PMC10705550 DOI: 10.1101/2023.11.21.568103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
Over the course of multiple divisions, cells accumulate diverse non-genetic, somatic damage including misfolded and aggregated proteins and cell wall defects. If the rate of damage accumulation exceeds the rate of dilution through cell growth, a dedicated mitigation strategy is required to prevent eventual population collapse. Strategies for somatic damage control can be divided into two categories, asymmetric allocation and repair, which are not, in principle, mutually exclusive. Through mathematical modelling, we identify the optimal strategy, maximizing the total cell number, over a wide range of environmental and physiological conditions. The optimal strategy is primarily determined by extrinsic (damage-independent) mortality and the physiological model for damage accumulation that can be either independent (linear) or increasing (exponential) with respect to the prior accumulated damage. Under the linear regime, the optimal strategy is either exclusively repair or asymmetric allocation whereas under the exponential regime, the optimal strategy is mixed. Repair is preferred when extrinsic mortality is low, whereas at high extrinsic mortality, asymmetric damage allocation becomes the strategy of choice. We hypothesize that optimization over somatic damage repair and asymmetric allocation in early cellular life forms gave rise to the r and K selection strategies.
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Affiliation(s)
- Dmitry A. Biba
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
- Oak Ridge Institute for Science and Education, Oak Ridge, TN, USA
| | - Yuri I. Wolf
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Nash D. Rochman
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
- Institute for Implementation Science in Population Health (ISPH), City University of New York (CUNY), New York, NY, USA
- Department of Epidemiology and Biostatistics, Graduate School of Public Health and Health Policy, City University of New York (CUNY), New York, NY, USA
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12
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Gupta R, Singh M, Pathania R. Chemical genetic approaches for the discovery of bacterial cell wall inhibitors. RSC Med Chem 2023; 14:2125-2154. [PMID: 37974958 PMCID: PMC10650376 DOI: 10.1039/d3md00143a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Accepted: 08/10/2023] [Indexed: 11/19/2023] Open
Abstract
Antimicrobial resistance (AMR) in bacterial pathogens is a worldwide health issue. The innovation gap in discovering new antibiotics has remained a significant hurdle in combating the AMR problem. Currently, antibiotics target various vital components of the bacterial cell envelope, nucleic acid and protein biosynthesis machinery and metabolic pathways essential for bacterial survival. The critical role of the bacterial cell envelope in cell morphogenesis and integrity makes it an attractive drug target. While a significant number of in-clinic antibiotics target peptidoglycan biosynthesis, several components of the bacterial cell envelope have been overlooked. This review focuses on various antibacterial targets in the bacterial cell wall and the strategies employed to find their novel inhibitors. This review will further elaborate on combining forward and reverse chemical genetic approaches to discover antibacterials that target the bacterial cell envelope.
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Affiliation(s)
- Rinki Gupta
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee Roorkee - 247 667 Uttarakhand India
| | - Mangal Singh
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee Roorkee - 247 667 Uttarakhand India
| | - Ranjana Pathania
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee Roorkee - 247 667 Uttarakhand India
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13
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Goudin A, Ferat JL, Possoz C, Barre FX, Galli E. Recovery of Vibrio cholerae polarized cellular organization after exit from a non-proliferating spheroplast state. PLoS One 2023; 18:e0293276. [PMID: 37883451 PMCID: PMC10602287 DOI: 10.1371/journal.pone.0293276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 10/10/2023] [Indexed: 10/28/2023] Open
Abstract
Vibrio cholerae, the causative agent of cholera epidemics, is a rod-shaped bacterium with a highly polarized cellular organization. It can survive harmful growth conditions by entering a non-proliferating spheroplast state, which involves loss of the cell envelope and polarity. How polarized rod organization cells are formed when the spheroplasts exit the non-proliferating state remains largely uncharacterized. To address this question, we investigated how L-arabinose-induced V. cholerae spheroplasts return to growth. We found that de novo morphogenesis started with the elimination of an excess of periplasm, which was immediately followed by cell elongation and the formation of cell branches with a diameter similar to that of normal V. cholerae cells. Periplasm elimination was driven by bifunctional peptidoglycan synthases involved in cell-wall maintenance, the aPBPs. Elongation and branching relied on the MreB-associated monofunctional peptidoglycan synthase PBP2. The cell division monofunctional peptidoglycan synthase FtsI was not involved in any of these processes. However, the FtsK cell division protein specifically targeted the sites of vesicle extrusion. Genetic material was amplified by synchronous waves of DNA replication as periplasmic elimination began. The HubP polarity factor targeted the tip of the branches as they began to form. However, HubP-mediated polarization was not involved in the efficiency of the recovery process. Finally, our results suggest that the positioning of HubP and the activities of the replication terminus organizer of the two V. cholerae chromosomes, MatP, are independent of cell division. Taken together, these results confirm the interest of L-arabinose-induced V. cholerae spheroplasts to study how cell shape is generated and shed light on the de novo establishment of the intracellular organization and cell polarization in V. cholerae.
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Affiliation(s)
- Anthony Goudin
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | - Jean-Luc Ferat
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | - Christophe Possoz
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | - François-Xavier Barre
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | - Elisa Galli
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
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14
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Midonet C, Bisset S, Shlosman I, Cava F, Rudner DZ, Bernhardt TG. MacP bypass variants of Streptococcus pneumoniae PBP2a suggest a conserved mechanism for the activation of bifunctional cell wall synthases. mBio 2023; 14:e0239023. [PMID: 37847021 PMCID: PMC10746261 DOI: 10.1128/mbio.02390-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 09/06/2023] [Indexed: 10/18/2023] Open
Abstract
The peptidoglycan (PG) layer protects bacteria from osmotic lysis and defines their shape. The class A penicillin-binding proteins (aPBPs) are PG synthases that possess both glycan polymerization and crosslinking activities needed for PG biogenesis. In Gram-negative bacteria, aPBPs require activation by outer membrane lipoproteins, which are thought to stimulate their cognate synthase by inducing conformational changes that promote polymerase function. How aPBPs are controlled in Gram-positive bacteria is less clear. One of the few known regulators is MacP in Streptococcus pneumoniae (Sp). MacP is required for the activity of Sp PBP2a, but its mode of action has been obscure. We therefore selected for PBP2a variants capable of functioning in the absence of MacP. Amino acid substitutions that bypassed the MacP requirement for PBP2a function in vivo also activated its polymerase activity in vitro. Many of these changes mapped to the interface between the transmembrane (TM) helix and polymerase domain in a model PBP2a structure. This region is conformationally flexible in the experimentally determined structures of aPBPs and undergoes a structural transition upon binding the substrate-mimicking drug moenomycin. Our findings suggest that MacP promotes PG polymerization by altering the TM-polymerase domain interface in PBP2a and that this mechanism for aPBP activation may be broadly conserved. Furthermore, Sp cells expressing an activated PBP2a variant displayed heterogeneous shapes, highlighting the importance of proper aPBP regulation in cell morphogenesis.IMPORTANCEClass A penicillin-binding proteins (aPBPs) play critical roles in bacterial cell wall biogenesis. As the targets of penicillin, they are among the most important drug targets in history. Although the biochemical activities of these enzymes have been well studied, little is known about how they are regulated in cells to control when and where peptidoglycan is made. In this report, we isolate variants of the Streptococcus pneumoniae enzyme PBP2a that function in cells without MacP, a partner normally required for its activity. The amino acid substitutions activate the cell wall synthase activity of PBP2a, and their location in a model structure suggests an activation mechanism for this enzyme that is shared with aPBPs from distantly related organisms with distinct activators.
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Affiliation(s)
- Caroline Midonet
- Department of Microbiology, Harvard Medical School, Blavatnik Institute, Boston, Massachusetts, USA
| | - Sean Bisset
- Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Irina Shlosman
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, Massachusetts, USA
| | - Felipe Cava
- Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Center for Microbial Research (UCMR), Umea, Sweden
- Department of Molecular Biology, Science for Life Laboratory (SciLifeLab), Umeå University, Umeå, Sweden
| | - David Z. Rudner
- Department of Microbiology, Harvard Medical School, Blavatnik Institute, Boston, Massachusetts, USA
| | - Thomas G. Bernhardt
- Department of Microbiology, Harvard Medical School, Blavatnik Institute, Boston, Massachusetts, USA
- Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
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15
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Kado T, Akbary Z, Motooka D, Sparks IL, Melzer ES, Nakamura S, Rojas ER, Morita YS, Siegrist MS. A cell wall synthase accelerates plasma membrane partitioning in mycobacteria. eLife 2023; 12:e81924. [PMID: 37665120 PMCID: PMC10547480 DOI: 10.7554/elife.81924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Accepted: 09/02/2023] [Indexed: 09/05/2023] Open
Abstract
Lateral partitioning of proteins and lipids shapes membrane function. In model membranes, partitioning can be influenced both by bilayer-intrinsic factors like molecular composition and by bilayer-extrinsic factors such as interactions with other membranes and solid supports. While cellular membranes can departition in response to bilayer-intrinsic or -extrinsic disruptions, the mechanisms by which they partition de novo are largely unknown. The plasma membrane of Mycobacterium smegmatis spatially and biochemically departitions in response to the fluidizing agent benzyl alcohol, then repartitions upon fluidizer washout. By screening for mutants that are sensitive to benzyl alcohol, we show that the bifunctional cell wall synthase PonA2 promotes membrane partitioning and cell growth during recovery from benzyl alcohol exposure. PonA2's role in membrane repartitioning and regrowth depends solely on its conserved transglycosylase domain. Active cell wall polymerization promotes de novo membrane partitioning and the completed cell wall polymer helps to maintain membrane partitioning. Our work highlights the complexity of membrane-cell wall interactions and establishes a facile model system for departitioning and repartitioning cellular membranes.
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Affiliation(s)
- Takehiro Kado
- Department of Microbiology, University of Massachusetts AmherstAmherstUnited States
| | - Zarina Akbary
- Department of Biology, New York UniversityNew YorkUnited States
| | - Daisuke Motooka
- Department of Infection Metagenomics, Research Institute for Microbial Diseases, Osaka UniversityOsakaJapan
| | - Ian L Sparks
- Department of Microbiology, University of Massachusetts AmherstAmherstUnited States
| | - Emily S Melzer
- Department of Microbiology, University of Massachusetts AmherstAmherstUnited States
| | - Shota Nakamura
- Department of Infection Metagenomics, Research Institute for Microbial Diseases, Osaka UniversityOsakaJapan
| | - Enrique R Rojas
- Department of Biology, New York UniversityNew YorkUnited States
| | - Yasu S Morita
- Department of Microbiology, University of Massachusetts AmherstAmherstUnited States
- Molecular and Cellular Graduate Program, University of Massachusetts AmherstAmherstUnited States
| | - M Sloan Siegrist
- Department of Microbiology, University of Massachusetts AmherstAmherstUnited States
- Molecular and Cellular Graduate Program, University of Massachusetts AmherstAmherstUnited States
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16
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Zhang H, Venkatesan S, Ng E, Nan B. Coordinated peptidoglycan synthases and hydrolases stabilize the bacterial cell wall. Nat Commun 2023; 14:5357. [PMID: 37660104 PMCID: PMC10475089 DOI: 10.1038/s41467-023-41082-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 08/21/2023] [Indexed: 09/04/2023] Open
Abstract
Peptidoglycan (PG) defines cell shape and protects bacteria against osmotic stress. The growth and integrity of PG require coordinated actions between synthases that insert new PG strands and hydrolases that generate openings to allow the insertion. However, the mechanisms of their coordination remain elusive. Moenomycin that inhibits a family of PG synthases known as Class-A penicillin-binding proteins (aPBPs), collapses rod shape despite aPBPs being non-essential for rod-like morphology in the bacterium Myxococcus xanthus. Here, we demonstrate that inhibited PBP1a2, an aPBP, accelerates the degradation of cell poles by DacB, a hydrolytic PG peptidase. Moenomycin promotes the binding between DacB and PG and thus reduces the mobility of DacB through PBP1a2. Conversely, DacB also regulates the distribution and dynamics of aPBPs. Our findings clarify the action of moenomycin and suggest that disrupting the coordination between PG synthases and hydrolases could be more lethal than eliminating individual enzymes.
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Affiliation(s)
- Huan Zhang
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Srutha Venkatesan
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Emily Ng
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Beiyan Nan
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA.
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17
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Shrestha S, Taib N, Gribaldo S, Shen A. Analyses of cell wall synthesis in Clostridioides difficile reveal a diversification in cell division mechanisms in endospore-forming bacteria. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.06.552200. [PMID: 37609260 PMCID: PMC10441361 DOI: 10.1101/2023.08.06.552200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Current models of bacterial cell division assume that the core synthases of the multiprotein divisome complex, FtsW-FtsI, are the primary drivers of septal peptidoglycan (PG) synthesis. These enzymes are typically encoded in the highly conserved division and cell wall (dcw) cluster and are considered to be universally essential for cell division. Here, we combine bioinformatics analyses with functional characterization in the pathogen Clostridioides difficile to show that dcw-encoded PG synthases have undergone a surprising specialization in the sole endospore-forming phylum, Firmicutes, to fulfill sporulation-specific roles. We describe a novel role for these enzymes in synthesizing septal PG during the sporulation-specific mode of cell division in C. difficile. Although these enzymes are directly regulated by canonical divisome components during this process, dcw-encoded PG synthases and their divisome regulators are unexpectedly dispensable for cell division during normal growth. Instead, C. difficile uses its sole bifunctional class A penicillin-binding protein (aPBP) to drive cell division, revealing a previously unreported role for this class of PG synthases as the core divisome enzyme. Collectively, our findings reveal how the emergence of endosporulation in the Firmicutes phylum was a key driver for the functional repurposing of an otherwise universally conserved cellular process such as cell division. Moreover, they indicate that C. difficile, and likely other clostridia, assemble a divisome that differs markedly from previously studied bacteria, thus representing an attractive, unique target for therapeutic purposes.
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Affiliation(s)
- Shailab Shrestha
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
- Program in Molecular Microbiology, Tufts University Graduate School of Biomedical Sciences, Boston, MA, USA
| | - Najwa Taib
- Institut Pasteur, Université de Paris, Unit Evolutionary Biology of the Microbial Cell, Paris, France
- Institut Pasteur, Université Paris Cité, Bioinformatics and Biostatistics Hub, F-75015 Paris, France
| | - Simonetta Gribaldo
- Institut Pasteur, Université de Paris, Unit Evolutionary Biology of the Microbial Cell, Paris, France
| | - Aimee Shen
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
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18
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Choi U, Park SH, Lee HB, Son JE, Lee CR. Coordinated and Distinct Roles of Peptidoglycan Carboxypeptidases DacC and DacA in Cell Growth and Shape Maintenance under Stress Conditions. Microbiol Spectr 2023; 11:e0001423. [PMID: 37098975 PMCID: PMC10269652 DOI: 10.1128/spectrum.00014-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 04/09/2023] [Indexed: 04/27/2023] Open
Abstract
Peptidoglycan (PG) is an essential bacterial architecture pivotal for shape maintenance and adaptation to osmotic stress. Although PG synthesis and modification are tightly regulated under harsh environmental stresses, few related mechanisms have been investigated. In this study, we aimed to investigate the coordinated and distinct roles of the PG dd-carboxypeptidases (DD-CPases) DacC and DacA in cell growth under alkaline and salt stresses and shape maintenance in Escherichia coli. We found that DacC is an alkaline DD-CPase, the enzyme activity and protein stability of which are significantly enhanced under alkaline stress. Both DacC and DacA were required for bacterial growth under alkaline stress, whereas only DacA was required for growth under salt stress. Under normal growth conditions, only DacA was necessary for cell shape maintenance, while under alkaline stress conditions, both DacA and DacC were necessary for cell shape maintenance, but their roles were distinct. Notably, all of these roles of DacC and DacA were independent of ld-transpeptidases, which are necessary for the formation of PG 3-3 cross-links and covalent bonds between PG and the outer membrane lipoprotein Lpp. Instead, DacC and DacA interacted with penicillin-binding proteins (PBPs)-dd-transpeptidases-mostly in a C-terminal domain-dependent manner, and these interactions were necessary for most of their roles. Collectively, our results demonstrate the coordinated and distinct novel roles of DD-CPases in bacterial growth and shape maintenance under stress conditions and provide novel insights into the cellular functions of DD-CPases associated with PBPs. IMPORTANCE Most bacteria have a peptidoglycan architecture for cell shape maintenance and protection against osmotic challenges. Peptidoglycan dd-carboxypeptidases control the amount of pentapeptide substrates, which are used in the formation of 4-3 cross-links by the peptidoglycan synthetic dd-transpeptidases, penicillin-binding proteins (PBPs). Seven dd-carboxypeptidases exist in Escherichia coli, but the physiological significance of their redundancy and their roles in peptidoglycan synthesis are poorly understood. Here, we showed that DacC is an alkaline dd-carboxypeptidase for which both protein stability and enzyme activity are significantly enhanced at high pH. Strikingly, dd-carboxypeptidases DacC and DacA physically interacted with PBPs, and these interactions were necessary for cell shape maintenance as well as growth under alkaline and salt stresses. Thus, cooperation between dd-carboxypeptidases and PBPs may allow E. coli to overcome various stresses and to maintain cell shape.
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Affiliation(s)
- Umji Choi
- Department of Biological Sciences, Myongji University, Yongin, Gyeonggido, Republic of Korea
| | - Si Hyoung Park
- Department of Biological Sciences, Myongji University, Yongin, Gyeonggido, Republic of Korea
| | - Han Byeol Lee
- Department of Biological Sciences, Myongji University, Yongin, Gyeonggido, Republic of Korea
| | - Ji Eun Son
- Department of Biological Sciences, Myongji University, Yongin, Gyeonggido, Republic of Korea
| | - Chang-Ro Lee
- Department of Biological Sciences, Myongji University, Yongin, Gyeonggido, Republic of Korea
- The Natural Science Research Institute, Myongji University, Yongin, Gyeonggido, Republic of Korea
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19
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Shlosman I, Fivenson EM, Gilman MSA, Sisley TA, Walker S, Bernhardt TG, Kruse AC, Loparo JJ. Allosteric activation of cell wall synthesis during bacterial growth. Nat Commun 2023; 14:3439. [PMID: 37301887 PMCID: PMC10257715 DOI: 10.1038/s41467-023-39037-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 05/25/2023] [Indexed: 06/12/2023] Open
Abstract
The peptidoglycan (PG) cell wall protects bacteria against osmotic lysis and determines cell shape, making this structure a key antibiotic target. Peptidoglycan is a polymer of glycan chains connected by peptide crosslinks, and its synthesis requires precise spatiotemporal coordination between glycan polymerization and crosslinking. However, the molecular mechanism by which these reactions are initiated and coupled is unclear. Here we use single-molecule FRET and cryo-EM to show that an essential PG synthase (RodA-PBP2) responsible for bacterial elongation undergoes dynamic exchange between closed and open states. Structural opening couples the activation of polymerization and crosslinking and is essential in vivo. Given the high conservation of this family of synthases, the opening motion that we uncovered likely represents a conserved regulatory mechanism that controls the activation of PG synthesis during other cellular processes, including cell division.
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Affiliation(s)
- Irina Shlosman
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Elayne M Fivenson
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Morgan S A Gilman
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Tyler A Sisley
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Suzanne Walker
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Thomas G Bernhardt
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, 02115, USA
- Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts, 02115, USA
| | - Andrew C Kruse
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, 02115, USA.
| | - Joseph J Loparo
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, 02115, USA.
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20
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Kawai Y, Errington J. Dissecting the roles of peptidoglycan synthetic and autolytic activities in the walled to L-form bacterial transition. Front Microbiol 2023; 14:1204979. [PMID: 37333659 PMCID: PMC10272550 DOI: 10.3389/fmicb.2023.1204979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 05/10/2023] [Indexed: 06/20/2023] Open
Abstract
Bacterial cells are surrounded by a peptidoglycan (PG) wall, which is a crucial target for antibiotics. It is well known that treatment with cell wall-active antibiotics occasionally converts bacteria to a non-walled "L-form" state that requires the loss of cell wall integrity. L-forms may have an important role in antibiotic resistance and recurrent infection. Recent work has revealed that inhibition of de novo PG precursor synthesis efficiently induces the L-form conversion in a wide range of bacteria, but the molecular mechanisms remain poorly understood. Growth of walled bacteria requires the orderly expansion of the PG layer, which involves the concerted action not just of synthases but also degradative enzymes called autolysins. Most rod-shaped bacteria have two complementary systems for PG insertion, the Rod and aPBP systems. Bacillus subtilis has two major autolysins, called LytE and CwlO, which are thought to have partially redundant functions. We have dissected the functions of autolysins, relative to the Rod and aPBP systems, during the switch to L-form state. Our results suggest that when de novo PG precursor synthesis is inhibited, residual PG synthesis occurs specifically via the aPBP pathway, and that this is required for continued autolytic activity by LytE/CwlO, resulting in cell bulging and efficient L-form emergence. The failure of L-form generation in cells lacking aPBPs was rescued by enhancing the Rod system and in this case, emergence specifically required LytE but was not associated with cell bulging. Our results suggest that two distinct pathways of L-form emergence exist depending on whether PG synthesis is being supported by the aPBP or RodA PG synthases. This work provides new insights into mechanisms of L-form generation, and specialisation in the roles of essential autolysins in relation to the recently recognised dual PG synthetic systems of bacteria.
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Kim K, Wang T, Ma HR, Şimşek E, Li B, Andreani V, You L. Mapping single‐cell responses to population‐level dynamics during antibiotic treatment. Mol Syst Biol 2023; 19:e11475. [PMCID: PMC10333910 DOI: 10.15252/msb.202211475] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 04/24/2023] [Accepted: 04/25/2023] [Indexed: 12/08/2023] Open
Abstract
Treatment of sensitive bacteria with beta‐lactam antibiotics often leads to two salient population‐level features: a transient increase in total population biomass before a subsequent decline, and a linear correlation between growth and killing rates. However, it remains unclear how these population‐level responses emerge from collective single‐cell responses. During beta‐lactam treatment, it is well‐recognized that individual cells often exhibit varying degrees of filamentation before lysis. We show that the cumulative probability of cell lysis increases sigmoidally with the extent of filamentation and that this dependence is characterized by unique parameters that are specific to bacterial strain, antibiotic dose, and growth condition. Modeling demonstrates how the single‐cell lysis probabilities can give rise to population‐level biomass dynamics, which were experimentally validated. This mapping provides insights into how the population biomass time‐kill curve emerges from single cells and allows the representation of both single‐ and population‐level responses with universal parameters.
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Affiliation(s)
- Kyeri Kim
- Department of Biomedical EngineeringDuke UniversityDurhamNCUSA
- Center for Quantitative BiodesignDuke UniversityDurhamNCUSA
| | - Teng Wang
- Department of Biomedical EngineeringDuke UniversityDurhamNCUSA
- Center for Quantitative BiodesignDuke UniversityDurhamNCUSA
| | - Helena R Ma
- Department of Biomedical EngineeringDuke UniversityDurhamNCUSA
- Center for Quantitative BiodesignDuke UniversityDurhamNCUSA
| | - Emrah Şimşek
- Department of Biomedical EngineeringDuke UniversityDurhamNCUSA
- Center for Quantitative BiodesignDuke UniversityDurhamNCUSA
| | - Boyan Li
- Integrated Science Program, Yuanpei CollegePeking UniversityBeijingChina
| | - Virgile Andreani
- Biomedical Engineering DepartmentBoston UniversityBostonMAUSA
- Biological Design CenterBoston UniversityBostonMAUSA
| | - Lingchong You
- Department of Biomedical EngineeringDuke UniversityDurhamNCUSA
- Center for Quantitative BiodesignDuke UniversityDurhamNCUSA
- Center for Genomic and Computational BiologyDuke UniversityDurhamNCUSA
- Department of Molecular Genetics and MicrobiologyDuke University School of MedicineDurhamNCUSA
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22
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Simon F, Tinevez JY, van Teeffelen S. ExTrack characterizes transition kinetics and diffusion in noisy single-particle tracks. J Cell Biol 2023; 222:e202208059. [PMID: 36880553 PMCID: PMC9997658 DOI: 10.1083/jcb.202208059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 12/01/2022] [Accepted: 01/27/2023] [Indexed: 03/08/2023] Open
Abstract
Single-particle tracking microscopy is a powerful technique to investigate how proteins dynamically interact with their environment in live cells. However, the analysis of tracks is confounded by noisy molecule localization, short tracks, and rapid transitions between different motion states, notably between immobile and diffusive states. Here, we propose a probabilistic method termed ExTrack that uses the full spatio-temporal information of tracks to extract global model parameters, to calculate state probabilities at every time point, to reveal distributions of state durations, and to refine the positions of bound molecules. ExTrack works for a wide range of diffusion coefficients and transition rates, even if experimental data deviate from model assumptions. We demonstrate its capacity by applying it to slowly diffusing and rapidly transitioning bacterial envelope proteins. ExTrack greatly increases the regime of computationally analyzable noisy single-particle tracks. The ExTrack package is available in ImageJ and Python.
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Affiliation(s)
- François Simon
- Département de Microbiologie, Infectiologie, et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, Quebec, Canada
- Microbial Morphogenesis and Growth Lab, Institut Pasteur, Université de Paris Cité, Paris, France
| | - Jean-Yves Tinevez
- Image Analysis Hub, Institut Pasteur, Université de Paris Cité, Paris, France
| | - Sven van Teeffelen
- Département de Microbiologie, Infectiologie, et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, Quebec, Canada
- Microbial Morphogenesis and Growth Lab, Institut Pasteur, Université de Paris Cité, Paris, France
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23
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Simon F, Tinevez JY, van Teeffelen S. ExTrack characterizes transition kinetics and diffusion in noisy single-particle tracks. J Cell Biol 2023; 222:e202208059. [PMID: 36880553 PMCID: PMC9997658 DOI: 10.1083/jcb.202208059 10.1101/2022.07.13.499913] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 12/01/2022] [Accepted: 01/27/2023] [Indexed: 03/23/2024] Open
Abstract
Single-particle tracking microscopy is a powerful technique to investigate how proteins dynamically interact with their environment in live cells. However, the analysis of tracks is confounded by noisy molecule localization, short tracks, and rapid transitions between different motion states, notably between immobile and diffusive states. Here, we propose a probabilistic method termed ExTrack that uses the full spatio-temporal information of tracks to extract global model parameters, to calculate state probabilities at every time point, to reveal distributions of state durations, and to refine the positions of bound molecules. ExTrack works for a wide range of diffusion coefficients and transition rates, even if experimental data deviate from model assumptions. We demonstrate its capacity by applying it to slowly diffusing and rapidly transitioning bacterial envelope proteins. ExTrack greatly increases the regime of computationally analyzable noisy single-particle tracks. The ExTrack package is available in ImageJ and Python.
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Affiliation(s)
- François Simon
- Département de Microbiologie, Infectiologie, et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, Quebec, Canada
- Microbial Morphogenesis and Growth Lab, Institut Pasteur, Université de Paris Cité, Paris, France
| | - Jean-Yves Tinevez
- Image Analysis Hub, Institut Pasteur, Université de Paris Cité, Paris, France
| | - Sven van Teeffelen
- Département de Microbiologie, Infectiologie, et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, Quebec, Canada
- Microbial Morphogenesis and Growth Lab, Institut Pasteur, Université de Paris Cité, Paris, France
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24
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Willdigg JR, Patel Y, Helmann JD. A Decrease in Fatty Acid Synthesis Rescues Cells with Limited Peptidoglycan Synthesis Capacity. mBio 2023; 14:e0047523. [PMID: 37017514 PMCID: PMC10128001 DOI: 10.1128/mbio.00475-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 03/13/2023] [Indexed: 04/06/2023] Open
Abstract
Proper synthesis and maintenance of a multilayered cell envelope are critical for bacterial fitness. However, whether mechanisms exist to coordinate synthesis of the membrane and peptidoglycan layers is unclear. In Bacillus subtilis, synthesis of peptidoglycan (PG) during cell elongation is mediated by an elongasome complex acting in concert with class A penicillin-binding proteins (aPBPs). We previously described mutant strains limited in their capacity for PG synthesis due to a loss of aPBPs and an inability to compensate by upregulation of elongasome function. Growth of these PG-limited cells can be restored by suppressor mutations predicted to decrease membrane synthesis. One suppressor mutation leads to an altered function repressor, FapR*, that functions as a super-repressor and leads to decreased transcription of fatty acid synthesis (FAS) genes. Consistent with fatty acid limitation mitigating cell wall synthesis defects, inhibition of FAS by cerulenin also restored growth of PG-limited cells. Moreover, cerulenin can counteract the inhibitory effect of β-lactams in some strains. These results imply that limiting PG synthesis results in impaired growth, in part, due to an imbalance of PG and cell membrane synthesis and that B. subtilis lacks a robust physiological mechanism to reduce membrane synthesis when PG synthesis is impaired. IMPORTANCE Understanding how a bacterium coordinates cell envelope synthesis is essential to fully appreciate how bacteria grow, divide, and resist cell envelope stresses, such as β-lactam antibiotics. Balanced synthesis of the peptidoglycan cell wall and the cell membrane is critical for cells to maintain shape and turgor pressure and to resist external cell envelope threats. Using Bacillus subtilis, we show that cells deficient in peptidoglycan synthesis can be rescued by compensatory mutations that decrease the synthesis of fatty acids. Further, we show that inhibiting fatty acid synthesis with cerulenin is sufficient to restore growth of cells deficient in peptidoglycan synthesis. Understanding the coordination of cell wall and membrane synthesis may provide insights relevant to antimicrobial treatment.
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Affiliation(s)
| | - Yesha Patel
- Department of Microbiology, Cornell University, Ithaca, New York, USA
| | - John D. Helmann
- Department of Microbiology, Cornell University, Ithaca, New York, USA
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25
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Galinier A, Delan-Forino C, Foulquier E, Lakhal H, Pompeo F. Recent Advances in Peptidoglycan Synthesis and Regulation in Bacteria. Biomolecules 2023; 13:biom13050720. [PMID: 37238589 DOI: 10.3390/biom13050720] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 04/17/2023] [Accepted: 04/21/2023] [Indexed: 05/28/2023] Open
Abstract
Bacteria must synthesize their cell wall and membrane during their cell cycle, with peptidoglycan being the primary component of the cell wall in most bacteria. Peptidoglycan is a three-dimensional polymer that enables bacteria to resist cytoplasmic osmotic pressure, maintain their cell shape and protect themselves from environmental threats. Numerous antibiotics that are currently used target enzymes involved in the synthesis of the cell wall, particularly peptidoglycan synthases. In this review, we highlight recent progress in our understanding of peptidoglycan synthesis, remodeling, repair, and regulation in two model bacteria: the Gram-negative Escherichia coli and the Gram-positive Bacillus subtilis. By summarizing the latest findings in this field, we hope to provide a comprehensive overview of peptidoglycan biology, which is critical for our understanding of bacterial adaptation and antibiotic resistance.
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Affiliation(s)
- Anne Galinier
- Laboratoire de Chimie Bactérienne, UMR 7283, Institut de Microbiologie de la Méditerranée, CNRS/Aix-Marseille Univ, 31 Chemin Joseph Aiguier, 13009 Marseille, France
| | - Clémentine Delan-Forino
- Laboratoire de Chimie Bactérienne, UMR 7283, Institut de Microbiologie de la Méditerranée, CNRS/Aix-Marseille Univ, 31 Chemin Joseph Aiguier, 13009 Marseille, France
| | - Elodie Foulquier
- Laboratoire de Chimie Bactérienne, UMR 7283, Institut de Microbiologie de la Méditerranée, CNRS/Aix-Marseille Univ, 31 Chemin Joseph Aiguier, 13009 Marseille, France
| | - Hakima Lakhal
- Laboratoire de Chimie Bactérienne, UMR 7283, Institut de Microbiologie de la Méditerranée, CNRS/Aix-Marseille Univ, 31 Chemin Joseph Aiguier, 13009 Marseille, France
| | - Frédérique Pompeo
- Laboratoire de Chimie Bactérienne, UMR 7283, Institut de Microbiologie de la Méditerranée, CNRS/Aix-Marseille Univ, 31 Chemin Joseph Aiguier, 13009 Marseille, France
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26
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Nguyen HTV, Chen X, Parada C, Luo AC, Shih O, Jeng US, Huang CY, Shih YL, Ma C. Structure of the heterotrimeric membrane protein complex FtsB-FtsL-FtsQ of the bacterial divisome. Nat Commun 2023; 14:1903. [PMID: 37019934 PMCID: PMC10076392 DOI: 10.1038/s41467-023-37543-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 03/21/2023] [Indexed: 04/07/2023] Open
Abstract
The synthesis of the cell-wall peptidoglycan during bacterial cell division is mediated by a multiprotein machine, called the divisome. The essential membrane protein complex of FtsB, FtsL and FtsQ (FtsBLQ) is at the heart of the divisome assembly cascade in Escherichia coli. This complex regulates the transglycosylation and transpeptidation activities of the FtsW-FtsI complex and PBP1b via coordination with FtsN, the trigger for the onset of constriction. Yet the underlying mechanism of FtsBLQ-mediated regulation is largely unknown. Here, we report the full-length structure of the heterotrimeric FtsBLQ complex, which reveals a V-shaped architecture in a tilted orientation. Such a conformation could be strengthened by the transmembrane and the coiled-coil domains of the FtsBL heterodimer, as well as an extended β-sheet of the C-terminal interaction site involving all three proteins. This trimeric structure may also facilitate interactions with other divisome proteins in an allosteric manner. These results lead us to propose a structure-based model that delineates the mechanism of the regulation of peptidoglycan synthases by the FtsBLQ complex.
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Affiliation(s)
- Hong Thuy Vy Nguyen
- Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan
- Chemical Biology and Molecular Biophysics program, Taiwan International Graduate Program, Academia Sinica, Taipei, 115, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, Taipei, 10617, Taiwan
| | - Xiaorui Chen
- Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan
| | - Claudia Parada
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115, Taiwan
| | - An-Chi Luo
- Institute of Biochemical Sciences, National Taiwan University, Taipei, 10617, Taiwan
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115, Taiwan
| | - Orion Shih
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - U-Ser Jeng
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu, 30044, Taiwan
| | - Chia-Ying Huang
- Paul Scherrer Institute, Forschungsstrasse 111, Villigen-PSI, 5232, Switzerland
| | - Yu-Ling Shih
- Institute of Biochemical Sciences, National Taiwan University, Taipei, 10617, Taiwan.
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115, Taiwan.
| | - Che Ma
- Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan.
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27
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Abstract
Most bacteria have cell wall peptidoglycan surrounding their plasma membranes. The essential cell wall provides a scaffold for the envelope, protection against turgor pressure and is a proven drug target. Synthesis of the cell wall involves reactions that span cytoplasmic and periplasmic compartments. Bacteria carry out the last steps of cell wall synthesis along their plasma membrane. The plasma membrane in bacteria is heterogeneous and contains membrane compartments. Here, I outline findings that highlight the emerging notion that plasma membrane compartments and the cell wall peptidoglycan are functionally intertwined. I start by providing models of cell wall synthesis compartmentalization within the plasma membrane in mycobacteria, Escherichia coli, and Bacillus subtilis. Then, I revisit literature that supports a role for the plasma membrane and its lipids in modulating enzymatic reactions that synthesize cell wall precursors. I also elaborate on what is known about bacterial lateral organization of the plasma membrane and the mechanisms by which organization is established and maintained. Finally, I discuss the implications of cell wall partitioning in bacteria and highlight how targeting plasma membrane compartmentalization serves as a way to disrupt cell wall synthesis in diverse species.
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Affiliation(s)
- Alam García-Heredia
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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28
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Deletion of pbpC Enhances Bacterial Pathogenicity on Tomato by Affecting Biofilm Formation, Exopolysaccharides Production, and Exoenzyme Activities in Clavibacter michiganensis. Int J Mol Sci 2023; 24:ijms24065324. [PMID: 36982399 PMCID: PMC10049144 DOI: 10.3390/ijms24065324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 02/14/2023] [Accepted: 03/07/2023] [Indexed: 03/18/2023] Open
Abstract
Penicillin-binding proteins (PBPs) are considered essential for bacterial peptidoglycan biosynthesis and cell wall assembly. Clavibacter michiganensis is a representative Gram-positive bacterial species that causes bacterial canker in tomato. pbpC plays a significant role in maintaining cell morphological characteristics and stress responses in C. michiganensis. The current study demonstrated that the deletion of pbpC commonly enhances bacterial pathogenicity in C. michiganensis and revealed the mechanisms through which this occurs. The expression of interrelated virulence genes, including celA, xysA, xysB, and pelA, were significantly upregulated in △pbpC mutants. Compared with those in wild-type strains, exoenzyme activities, the formation of biofilm, and the production of exopolysaccharides (EPS) were significantly increased in △pbpC mutants. It is noteworthy that EPS were responsible for the enhancement in bacterial pathogenicity, with the degree of necrotic tomato stem cankers intensifying with the injection of a gradient of EPS from C. michiganensis. These findings highlight new insights into the role of pbpC affecting bacterial pathogenicity, with an emphasis on EPS, advancing the current understanding of phytopathogenic infection strategies for Gram-positive bacteria.
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Li R, Tao J, Huang D, Zhou W, Gao L, Wang X, Chen H, Huang H. Investigating the effects of biodegradable microplastics and copper ions on probiotic (Bacillus amyloliquefaciens): Toxicity and application. JOURNAL OF HAZARDOUS MATERIALS 2023; 443:130081. [PMID: 36367472 DOI: 10.1016/j.jhazmat.2022.130081] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 09/13/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
Currently, microplastic pollution is more serious and complicates the toxic effects of other co-existing pollutants in the environment. However, the effect and mechanism of biodegradable plastics on the growth and metabolism of probiotic remain unclear. This work selected Bacillus amyloliquefaciens as model bacterium for a three-day exposure experiment to probe the issues. The results showed that 100 mg/L polylactic acid microplastics (PLA MPs) (3-4 mm, flake shape) caused oxidative damage to cell membranes, disrupted cell wall composition and inhibited cell growth by 21.2-27.5 %. The toxicity was not simply additive or synergistic effects when PLA MPs (100 mg/L) and copper ions (10 mg/L) coexisted. PLA MPs did not significantly increase the toxicity of copper to bacteria, instead triggered some mechanisms to resist the toxicity of copper. The bacteria formed spores to resist PLA MPs, while the copper ions toxicity was weaken by chelation and efflux. It is worth noting that copper ions instead increased the expression of genes related fengycin and iturin then improving the bacteriostatic activity of the probiotic. This paper deeply analyzes the toxicity mechanism of combined pollution on Bacillus amyloliquefacien, and also provides new perspective for helping to inhibit pathogenic bacteria under biodegradable microplastics and metal stress.
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Affiliation(s)
- Ruijin Li
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Jiaxi Tao
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Danlian Huang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China.
| | - Wei Zhou
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Lan Gao
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Xinya Wang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Haojie Chen
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
| | - Hai Huang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082, PR China
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PBP1A Directly Interacts with the Divisome Complex to Promote Septal Peptidoglycan Synthesis in Acinetobacter baumannii. J Bacteriol 2022; 204:e0023922. [PMID: 36317921 PMCID: PMC9765026 DOI: 10.1128/jb.00239-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The class A penicillin-binding proteins (aPBPs), PBP1A and PBP1B, are major peptidoglycan synthases that synthesize more than half of the peptidoglycan per generation in Escherichia coli. Whereas aPBPs have distinct roles in peptidoglycan biosynthesis during growth (i.e., elongation and division), they are semiredundant; disruption of either is rescued by the other to maintain envelope homeostasis and promote proper growth. Acinetobacter baumannii is a nosocomial pathogen that has a high propensity to overcome antimicrobial treatment. A. baumannii contains both PBP1A and PBP1B (encoded by mrcA and mrcB, respectively), but only mrcA deletion decreased fitness and contributed to colistin resistance through inactivation of lipooligosaccharide biosynthesis, indicating that PBP1B was not functionally redundant with the PBP1A activity. While previous studies suggested a distinct role for PBP1A in division, it was unknown whether its role in septal peptidoglycan biosynthesis was direct. Here, we show that A. baumannii PBP1A has a direct role in division through interactions with divisome components. PBP1A localizes to septal sites during growth, where it interacts with the transpeptidase PBP3, an essential division component that regulates daughter cell formation. PBP3 overexpression was sufficient to rescue the division defect in ΔmrcA A. baumannii; however, PBP1A overexpression was not sufficient to rescue the septal defect when PBP3 was inhibited, suggesting that their activity is not redundant. Overexpression of a major dd-carboxypeptidase, PBP5, also restored the canonical A. baumannii coccobacilli morphology in ΔmrcA cells. Together, these data support a direct role for PBP1A in A. baumannii division and highlights its role as a septal peptidoglycan synthase. IMPORTANCE Peptidoglycan biosynthesis is a validated target of β-lactam antibiotics, and it is critical that we understand essential processes in multidrug-resistant pathogens such as Acinetobacter baumannii. While model systems such as Escherichia coli have shown that PBP1A is associated with side wall peptidoglycan synthesis, we show herein that A. baumannii PBP1A directly interacts with the divisome component PBP3 to promote division, suggesting a unique role for the enzyme in this highly drug-resistant nosocomial pathogen. A. baumannii demonstrated unanticipated resistance and tolerance to envelope-targeting antibiotics, which may be driven by rewired peptidoglycan machinery and may underlie therapeutic failure during antibiotic treatment.
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31
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Schulz LM, Rothe P, Halbedel S, Gründling A, Rismondo J. Imbalance of peptidoglycan biosynthesis alters the cell surface charge of Listeria monocytogenes. Cell Surf 2022; 8:100085. [PMID: 36304571 PMCID: PMC9593813 DOI: 10.1016/j.tcsw.2022.100085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 10/19/2022] [Accepted: 10/19/2022] [Indexed: 02/09/2023] Open
Abstract
The bacterial cell wall is composed of a thick layer of peptidoglycan and cell wall polymers, which are either embedded in the membrane or linked to the peptidoglycan backbone and referred to as lipoteichoic acid (LTA) and wall teichoic acid (WTA), respectively. Modifications of the peptidoglycan or WTA backbone can alter the susceptibility of the bacterial cell towards cationic antimicrobials and lysozyme. The human pathogen Listeria monocytogenes is intrinsically resistant towards lysozyme, mainly due to deacetylation and O-acetylation of the peptidoglycan backbone via PgdA and OatA. Recent studies identified additional factors, which contribute to the lysozyme resistance of this pathogen. One of these is the predicted ABC transporter, EslABC. An eslB mutant is hyper-sensitive towards lysozyme, likely due to the production of thinner and less O-acetylated peptidoglycan. Using a suppressor screen, we show here that suppression of eslB phenotypes could be achieved by enhancing peptidoglycan biosynthesis, reducing peptidoglycan hydrolysis or alterations in WTA biosynthesis and modification. The lack of EslB also leads to a higher negative surface charge, which likely stimulates the activity of peptidoglycan hydrolases and lysozyme. Based on our results, we hypothesize that the portion of cell surface exposed WTA is increased in the eslB mutant due to the thinner peptidoglycan layer and that latter one could be caused by an impairment in UDP-N-acetylglucosamine (UDP-GlcNAc) production or distribution.
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Affiliation(s)
- Lisa Maria Schulz
- Department of General Microbiology, Institute of Microbiology and Genetics, GZMB, Georg-August University Göttingen, Grisebachstr. 8, 37077 Göttingen, Germany
| | - Patricia Rothe
- FG11, Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Burgstraße 37, 38855 Wernigerode, Germany
| | - Sven Halbedel
- FG11, Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Burgstraße 37, 38855 Wernigerode, Germany
- Institute for Medical Microbiology and Hospital Hygiene, Otto von Guericke University Magdeburg, Leipziger Straße 44, 39120 Magdeburg, Germany
| | - Angelika Gründling
- Section of Molecular Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom
| | - Jeanine Rismondo
- Department of General Microbiology, Institute of Microbiology and Genetics, GZMB, Georg-August University Göttingen, Grisebachstr. 8, 37077 Göttingen, Germany
- Section of Molecular Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, United Kingdom
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Costigan R, Stoakes E, Floto RA, Parkhill J, Grant AJ. Development and validation of a CRISPR interference system for gene regulation in Campylobacter jejuni. BMC Microbiol 2022; 22:238. [PMID: 36199015 PMCID: PMC9533551 DOI: 10.1186/s12866-022-02645-4] [Citation(s) in RCA: 3] [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: 04/28/2022] [Accepted: 09/15/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Campylobacter spp. are the leading cause of bacterial food-borne illness in humans worldwide, with Campylobacter jejuni responsible for 80% of these infections. There is an urgent need to understand fundamental C. jejuni biology for the development of new strategies to prevent and treat infections. The range of molecular tools available to regulate gene expression in C. jejuni is limited, which in turn constrains our ability to interrogate the function of essential and conditionally essential genes. We have addressed this by developing and utilising a CRISPR-based interference system known as CRISPRi in C. jejuni to control gene expression. To achieve this, a catalytically inactive ("dead") cas9 and sgRNA backbone from the Streptococcus pyogenes CRISPRi system was combined with C. jejuni-derived promoters of predetermined expression activities to develop a CRISPRi-based repression tool in C. jejuni strains M1Cam and 81-176. RESULTS The CRISPRi tool was validated through successful repression of the arylsulphatase-encoding gene astA using a range of sgRNA target sequences spanning the astA gene. The tool was also applied to target astA in an M1Cam CRISPR-Cas9 deletion strain, which showed that the presence of an endogenous CRISPR-Cas9 system did not affect the activity of the CRISPRi-based repression tool. The tool was further validated against the hippicurase-encoding gene hipO. Following this, the flagella genes flgR, flaA, flaB and both flaA and flaB were targeted for CRISPRi-based repression, which resulted in varying levels of motility reduction and flagella phenotypes as determined by phenotypical assays and transmission electron microscopy (TEM). CONCLUSIONS This is the first report of a CRISPRi-based tool in C. jejuni, which will provide a valuable resource to the Campylobacter community.
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Affiliation(s)
- Ruby Costigan
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - Emily Stoakes
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - R Andres Floto
- Department of Medicine, MRC-Laboratory of Molecular Biology, Molecular Immunity Unit, University of Cambridge, Cambridge, UK
- University of Cambridge, Centre for AI in Medicine, Cambridge, UK
- Cambridge Centre for Lung Infection, Papworth Hospital, Cambridge, UK
| | - Julian Parkhill
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - Andrew J Grant
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
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Lamanna MM, Manzoor I, Joseph M, Ye ZA, Benedet M, Zanardi A, Ren Z, Wang X, Massidda O, Tsui HT, Winkler ME. Roles of RodZ and class A PBP1b in the assembly and regulation of the peripheral peptidoglycan elongasome in ovoid-shaped cells of Streptococcus pneumoniae D39. Mol Microbiol 2022; 118:336-368. [PMID: 36001060 PMCID: PMC9804626 DOI: 10.1111/mmi.14969] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 07/30/2022] [Accepted: 08/02/2022] [Indexed: 01/17/2023]
Abstract
RodZ of rod-shaped bacteria functions to link MreB filaments to the Rod peptidoglycan (PG) synthase complex that moves circumferentially perpendicular to the long cell axis, creating hoop-like sidewall PG. Ovoid-shaped bacteria, such as Streptococcus pneumoniae (pneumococcus; Spn) that lack MreB, use a different modality for peripheral PG elongation that emanates from the midcell of dividing cells. Yet, S. pneumoniae encodes a RodZ homolog similar to RodZ in rod-shaped bacteria. We show here that the helix-turn-helix and transmembrane domains of RodZ(Spn) are essential for growth at 37°C. ΔrodZ mutations are suppressed by Δpbp1a, mpgA(Y488D), and ΔkhpA mutations that suppress ΔmreC, but not ΔcozE. Consistent with a role in PG elongation, RodZ(Spn) co-localizes with MreC and aPBP1a throughout the cell cycle and forms complexes and interacts with PG elongasome proteins and regulators. Depletion of RodZ(Spn) results in aberrantly shaped, non-growing cells and mislocalization of elongasome proteins MreC, PBP2b, and RodA. Moreover, Tn-seq reveals that RodZ(Spn), but not MreCD(Spn), displays a specific synthetic-viable genetic relationship with aPBP1b, whose function is unknown. We conclude that RodZ(Spn) acts as a scaffolding protein required for elongasome assembly and function and that aPBP1b, like aPBP1a, plays a role in elongasome regulation and possibly peripheral PG synthesis.
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Affiliation(s)
- Melissa M. Lamanna
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
| | - Irfan Manzoor
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
| | - Merrin Joseph
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
| | - Ziyun A. Ye
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
| | - Mattia Benedet
- Department of Cellular, Computational and Integrative Biology (CIBIO)University of TrentoTrentoItaly
| | - Alessia Zanardi
- Department of Cellular, Computational and Integrative Biology (CIBIO)University of TrentoTrentoItaly
| | - Zhongqing Ren
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
| | - Xindan Wang
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
| | - Orietta Massidda
- Department of Cellular, Computational and Integrative Biology (CIBIO)University of TrentoTrentoItaly
| | - Ho‐Ching T. Tsui
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
| | - Malcolm E. Winkler
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
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Lyu Z, Yahashiri A, Yang X, McCausland JW, Kaus GM, McQuillen R, Weiss DS, Xiao J. FtsN maintains active septal cell wall synthesis by forming a processive complex with the septum-specific peptidoglycan synthases in E. coli. Nat Commun 2022; 13:5751. [PMID: 36180460 PMCID: PMC9525312 DOI: 10.1038/s41467-022-33404-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 09/16/2022] [Indexed: 01/06/2023] Open
Abstract
FtsN plays an essential role in promoting the inward synthesis of septal peptidoglycan (sPG) by the FtsWI complex during bacterial cell division. How it achieves this role is unclear. Here we use single-molecule tracking to investigate FtsN's dynamics during sPG synthesis in E. coli. We show that septal FtsN molecules move processively at ~9 nm s-1, the same as FtsWI molecules engaged in sPG synthesis (termed sPG-track), but much slower than the ~30 nm s-1 speed of inactive FtsWI molecules coupled to FtsZ's treadmilling dynamics (termed FtsZ-track). Importantly, processive movement of FtsN is exclusively coupled to sPG synthesis and is required to maintain active sPG synthesis by FtsWI. Our findings indicate that FtsN is part of the FtsWI sPG synthesis complex, and that while FtsN is often described as a "trigger" for the initiation for cell wall constriction, it must remain part of the processive FtsWI complex to maintain sPG synthesis activity.
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Affiliation(s)
- Zhixin Lyu
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
| | - Atsushi Yahashiri
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Xinxing Yang
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
- The Chinese Academy of Sciences Key Laboratory of Innate Immunity and Chronic Disease, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Joshua W McCausland
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
| | - Gabriela M Kaus
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Ryan McQuillen
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
| | - David S Weiss
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA.
| | - Jie Xiao
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA.
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35
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Brunet YR, Habib C, Brogan AP, Artzi L, Rudner DZ. Intrinsically disordered protein regions are required for cell wall homeostasis in Bacillus subtilis. Genes Dev 2022; 36:970-984. [PMID: 36265902 PMCID: PMC9732909 DOI: 10.1101/gad.349895.122] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 10/03/2022] [Indexed: 01/07/2023]
Abstract
Intrinsically disordered protein regions (IDRs) have been implicated in diverse nuclear and cytoplasmic functions in eukaryotes, but their roles in bacteria are less clear. Here, we report that extracytoplasmic IDRs in Bacillus subtilis are required for cell wall homeostasis. The B. subtilis σI transcription factor is activated in response to envelope stress through regulated intramembrane proteolysis (RIP) of its membrane-anchored anti-σ factor, RsgI. Unlike canonical RIP pathways, we show that ectodomain (site-1) cleavage of RsgI is constitutive, but the two cleavage products remain stably associated, preventing intramembrane (site-2) proteolysis. The regulated step in this pathway is their dissociation, which is triggered by impaired cell wall synthesis and requires RsgI's extracytoplasmic IDR. Intriguingly, the major peptidoglycan polymerase PBP1 also contains an extracytoplasmic IDR, and we show that this region is important for its function. Disparate IDRs can replace the native IDRs on both RsgI and PBP1, arguing that these unstructured regions function similarly. Our data support a model in which the RsgI-σI signaling system and PBP1 represent complementary pathways to repair gaps in the PG meshwork. The IDR on RsgI senses these gaps and activates σI, while the IDR on PBP1 directs the synthase to these sites to fortify them.
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Affiliation(s)
- Yannick R. Brunet
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Cameron Habib
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Anna P. Brogan
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Lior Artzi
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - David Z. Rudner
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115, USA
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36
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Melzer ES, Kado T, García-Heredia A, Gupta KR, Meniche X, Morita YS, Sassetti CM, Rego EH, Siegrist MS. Cell Wall Damage Reveals Spatial Flexibility in Peptidoglycan Synthesis and a Nonredundant Role for RodA in Mycobacteria. J Bacteriol 2022; 204:e0054021. [PMID: 35543537 PMCID: PMC9210966 DOI: 10.1128/jb.00540-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 03/06/2022] [Indexed: 12/28/2022] Open
Abstract
Cell wall peptidoglycan is a heteropolymeric mesh that protects the bacterium from internal turgor and external insults. In many rod-shaped bacteria, peptidoglycan synthesis for normal growth is achieved by two distinct pathways: the Rod complex, comprised of MreB, RodA, and a cognate class B penicillin-binding protein (PBP), and the class A PBPs (aPBPs). In contrast to laterally growing bacteria, pole-growing mycobacteria do not encode an MreB homolog and do not require SEDS protein RodA for in vitro growth. However, RodA contributes to the survival of Mycobacterium tuberculosis in some infection models, suggesting that the protein could have a stress-dependent role in maintaining cell wall integrity. Under basal conditions, we find here that the subcellular distribution of RodA largely overlaps that of the aPBP PonA1 and that both RodA and the aPBPs promote polar peptidoglycan assembly. Upon cell wall damage, RodA fortifies Mycobacterium smegmatis against lysis and, unlike aPBPs, contributes to a shift in peptidoglycan assembly from the poles to the sidewall. Neither RodA nor PonA1 relocalize; instead, the redistribution of nascent cell wall parallels that of peptidoglycan precursor synthase MurG. Our results support a model in which mycobacteria balance polar growth and cell-wide repair via spatial flexibility in precursor synthesis and extracellular insertion. IMPORTANCE Peptidoglycan synthesis is a highly successful target for antibiotics. The pathway has been extensively studied in model organisms under laboratory-optimized conditions. In natural environments, bacteria are frequently under attack. Moreover, the vast majority of bacterial species are unlikely to fit a single paradigm of cell wall assembly because of differences in growth mode and/or envelope structure. Studying cell wall synthesis under nonoptimal conditions and in nonstandard species may improve our understanding of pathway function and suggest new inhibition strategies. Mycobacterium smegmatis, a relative of several notorious human and animal pathogens, has an unusual polar growth mode and multilayered envelope. In this work, we challenged M. smegmatis with cell wall-damaging enzymes to characterize the roles of cell wall-building enzymes when the bacterium is under attack.
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Affiliation(s)
- Emily S. Melzer
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA
| | - Takehiro Kado
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA
| | - Alam García-Heredia
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Massachusetts, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | | | - Xavier Meniche
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Yasu S. Morita
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Massachusetts, USA
| | - Christopher M. Sassetti
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - E. Hesper Rego
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - M. Sloan Siegrist
- Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Massachusetts, USA
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37
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Enhancing bioreactor arrays for automated measurements and reactive control with ReacSight. Nat Commun 2022; 13:3363. [PMID: 35690608 PMCID: PMC9188569 DOI: 10.1038/s41467-022-31033-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 05/31/2022] [Indexed: 12/19/2022] Open
Abstract
Small-scale, low-cost bioreactors provide exquisite control of environmental parameters of microbial cultures over long durations. Their use is gaining popularity in quantitative systems and synthetic biology. However, existing setups are limited in their measurement capabilities. Here, we present ReacSight, a strategy to enhance bioreactor arrays for automated measurements and reactive experiment control. ReacSight leverages low-cost pipetting robots for sample collection, handling and loading, and provides a flexible instrument control architecture. We showcase ReacSight capabilities on three applications in yeast. First, we demonstrate real-time optogenetic control of gene expression. Second, we explore the impact of nutrient scarcity on fitness and cellular stress using competition assays. Third, we perform dynamic control of the composition of a two-strain consortium. We combine custom or chi.bio reactors with automated cytometry. To further illustrate ReacSight's genericity, we use it to enhance plate-readers with pipetting capabilities and perform repeated antibiotic treatments on a bacterial clinical isolate.
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38
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Park S, Cho H. The Tol-Pal System Plays an Important Role in Maintaining Cell Integrity During Elongation in Escherichia coli. Front Microbiol 2022; 13:891926. [PMID: 35592005 PMCID: PMC9111525 DOI: 10.3389/fmicb.2022.891926] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/07/2022] [Indexed: 11/13/2022] Open
Abstract
The Tol-Pal system is a transenvelope complex widely conserved among Gram-negative bacteria. It is recruited to the septal ring during cytokinesis, and its inactivation causes pleiotropic phenotypes mainly associated with the division process. From our genetic screen to identify factors required for delaying lysis upon treatment of beta lactams, we discovered that the tol-pal mutant shares similar defects with mutants of the major class A PBP system (PBP1b-LpoB) in terms of lysis prevention. Further phenotypic analyses revealed that the Tol-Pal system plays an important role in maintaining cell integrity not only during septation, but also during cell elongation. Simultaneous inactivation of the Tol-Pal system and the PBP1b-LpoB system leads to lysis during cell elongation as well as during division. Moreover, production of the Lpo activator-bypass PBP1b, but not wild-type PBP1b, partially suppressed the Tol-Pal defect in maintaining cell integrity upon treatment of mecillinam specific for the Rod system, suggesting that the Tol-Pal system is likely to be involved in the activation of aPBP by Lpo factors. Overall, our results indicate that the Tol-Pal system plays an important role in maintaining cell wall integrity during elongation in addition to its multifaceted roles during cytokinesis.
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Affiliation(s)
- Sohee Park
- Department of Biological Sciences, College of Natural Sciences, Sungkyunkwan University, Suwon, South Korea
| | - Hongbaek Cho
- Department of Biological Sciences, College of Natural Sciences, Sungkyunkwan University, Suwon, South Korea
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39
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Lamanna MM, Maurelli AT. What Is Motion? Recent Advances in the Study of Molecular Movement Patterns of the Peptidoglycan Synthesis Machines. J Bacteriol 2022; 204:e0059821. [PMID: 34928180 PMCID: PMC9017339 DOI: 10.1128/jb.00598-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
How proteins move through space and time is a fundamental question in biology. While great strides have been made toward a mechanistic understanding of protein movement, many questions remain. We discuss the biological implications of motion in the context of the peptidoglycan (PG) synthesis machines. We reviewed systems in several bacteria, including Escherichia coli, Bacillus subtilis, and Streptococcus pneumoniae, and present a comprehensive view of our current knowledge regarding movement dynamics. Discrepancies are also addressed because "one size does not fit all". For bacteria to divide, new PG is synthesized and incorporated into the growing cell wall by complex multiprotein nanomachines consisting of PG synthases (transglycosylases [TG] and/or transpeptidases [TP]) as well as a variety of regulators and cytoskeletal factors. Advances in imaging capabilities and labeling methods have revealed that these machines are not static but rather circumferentially transit the cell via directed motion perpendicular to the long axis of model rod-shaped bacteria such as E. coli and B. subtilis. The enzymatic activity of the TG:TPs drives motion in some species while motion is mediated by FtsZ treadmilling in others. In addition, both directed and diffusive motion of the PG synthases have been observed using single-particle tracking technology. Here, we examined the biological role of diffusion regarding transit. Lastly, findings regarding the monofunctional transglycosylases (RodA and FtsW) as well as the Class A PG synthases are discussed. This minireview serves to showcase recent advances, broach mechanistic unknowns, and stimulate future areas of study.
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Affiliation(s)
- Melissa Mae Lamanna
- Department of Environmental & Global Health and Emerging Pathogens Institute, University of Floridagrid.15276.37, Gainesville, Florida, USA
| | - Anthony T. Maurelli
- Department of Environmental & Global Health and Emerging Pathogens Institute, University of Floridagrid.15276.37, Gainesville, Florida, USA
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40
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Interplay between Amoxicillin Resistance and Osmotic Stress in Helicobacter pylori. J Bacteriol 2022; 204:e0004522. [PMID: 35389254 DOI: 10.1128/jb.00045-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rising antibiotic resistance rates are a growing concern for all pathogens, including Helicobacter pylori. We previously examined the association of specific mutations in PBP1 with amoxicillin resistance and fitness in H. pylori and found that V374L and N562Y mutations were associated with resistance, but also resulted in fitness defects. Furthermore, we found that hyperosmotic stress differentially altered the fitness of strains bearing these mutations; survival of the V374L strain was decreased by hyperosmotic stress, but the N562Y strain showed increased cell survival relative to that of wild-type G27. The finding that amoxicillin-resistant strains show environmentally dictated changes in fitness suggests a previously unexplored interaction between amoxicillin resistance and osmotic stress in H. pylori. Here, we further characterized the interaction between osmotic stress and amoxicillin resistance. Wild-type and isogenic PBP1 mutant strains were exposed to amoxicillin, various osmotic stressors, or combined antibiotic and osmotic stress, and viability was monitored. While subinhibitory concentrations of NaCl did not affect H. pylori viability, the combination of NaCl and amoxicillin resulted in synergistic killing; this was true even for the antibiotic-resistant strains. Moreover, similar synergy was found with other beta-lactams, but not with antibiotics that did not target the cell wall. Similar synergistic killing was also demonstrated when KCl was utilized as the osmotic stressor. Conversely, osmolar equivalent concentrations of sucrose antagonized amoxicillin-mediated killing. Taken together, our results support a previously unrecognized interaction between amoxicillin resistance and osmotic stress in H. pylori. These findings have interesting implications for the effectiveness of antibiotic therapy for this pathogen. IMPORTANCE Rising antibiotic resistance rates in H. pylori are associated with increased rates of treatment failure. Understanding how stressors impact antibiotic resistance may shed light on the development of future treatment strategies. Previous studies found that mutations in PBP1 that conferred resistance to amoxicillin were also associated with a decrease in bacterial fitness. The current study demonstrated that osmotic stress can enhance beta lactam-mediated killing of H. pylori. The source of osmotic stress was found to be important for these interactions. Given that relatively little is known about how H. pylori responds to osmotic stress, these findings fill important knowledge gaps on this topic and provide interesting implications for the effectiveness of antibiotic therapy for this pathogen.
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Attaibi M, den Blaauwen T. An Updated Model of the Divisome: Regulation of the Septal Peptidoglycan Synthesis Machinery by the Divisome. Int J Mol Sci 2022; 23:3537. [PMID: 35408901 PMCID: PMC8998562 DOI: 10.3390/ijms23073537] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 02/06/2023] Open
Abstract
The synthesis of a peptidoglycan septum is a fundamental part of bacterial fission and is driven by a multiprotein dynamic complex called the divisome. FtsW and FtsI are essential proteins that synthesize the peptidoglycan septum and are controlled by the regulatory FtsBLQ subcomplex and the activator FtsN. However, their mode of regulation has not yet been uncovered in detail. Understanding this process in detail may enable the development of new compounds to combat the rise in antibiotic resistance. In this review, recent data on the regulation of septal peptidoglycan synthesis is summarized and discussed. Based on structural models and the collected data, multiple putative interactions within FtsWI and with regulators are uncovered. This elaborates on and supports an earlier proposed model that describes active and inactive conformations of the septal peptidoglycan synthesis complex that are stabilized by these interactions. Furthermore, a new model on the spatial organization of the newly synthesized peptidoglycan and the synthesis complex is presented. Overall, the updated model proposes a balance between several allosteric interactions that determine the state of septal peptidoglycan synthesis.
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Affiliation(s)
| | - Tanneke den Blaauwen
- Bacterial Cell Biology and Physiology, Swammerdam Institute for Life Science, University of Amsterdam, 1098 XH Amsterdam, The Netherlands;
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42
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Kumar S, Mollo A, Kahne D, Ruiz N. The Bacterial Cell Wall: From Lipid II Flipping to Polymerization. Chem Rev 2022; 122:8884-8910. [PMID: 35274942 PMCID: PMC9098691 DOI: 10.1021/acs.chemrev.1c00773] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The peptidoglycan (PG) cell wall is an extra-cytoplasmic glycopeptide polymeric structure that protects bacteria from osmotic lysis and determines cellular shape. Since the cell wall surrounds the cytoplasmic membrane, bacteria must add new material to the PG matrix during cell elongation and division. The lipid-linked precursor for PG biogenesis, Lipid II, is synthesized in the inner leaflet of the cytoplasmic membrane and is subsequently translocated across the bilayer so that the PG building block can be polymerized and cross-linked by complex multiprotein machines. This review focuses on major discoveries that have significantly changed our understanding of PG biogenesis in the past decade. In particular, we highlight progress made toward understanding the translocation of Lipid II across the cytoplasmic membrane by the MurJ flippase, as well as the recent discovery of a novel class of PG polymerases, the SEDS (shape, elongation, division, and sporulation) glycosyltransferases RodA and FtsW. Since PG biogenesis is an effective target of antibiotics, these recent developments may lead to the discovery of much-needed new classes of antibiotics to fight bacterial resistance.
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Affiliation(s)
- Sujeet Kumar
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Aurelio Mollo
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Daniel Kahne
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States.,Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, United States.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Natividad Ruiz
- Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, United States
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Abstract
While many mechanisms governing bacterial envelope homeostasis have been identified, others remain poorly understood. To decipher these processes, we previously developed an assay in the Gram-negative model Escherichia coli to identify genes involved in maintenance of envelope integrity. One such gene was ElyC, which was shown to be required for envelope integrity and peptidoglycan synthesis at room temperature. ElyC is predicted to be an integral inner membrane protein with a highly conserved domain of unknown function (DUF218). In this study, and stemming from a further characterization of the role of ElyC in maintaining cell envelope integrity, we serendipitously discovered an unappreciated form of oxidative stress in the bacterial envelope. We found that cells lacking ElyC overproduce hydroxyl radicals (HO•) in their envelope compartment and that HO• overproduction is directly or indirectly responsible for the peptidoglycan synthesis arrest, cell envelope integrity defects, and cell lysis of the ΔelyC mutant. Consistent with these observations, we show that the ΔelyC mutant defect is suppressed during anaerobiosis. HO• is known to cause DNA damage but to our knowledge has not been shown to interfere with peptidoglycan synthesis. Thus, our work implicates oxidative stress as an important stressor in the bacterial cell envelope and opens the door to future studies deciphering the mechanisms that render peptidoglycan synthesis sensitive to oxidative stress. IMPORTANCE Oxidative stress is caused by the production and excessive accumulation of oxygen reactive species. In bacterial cells, oxidative stress mediated by hydroxyl radicals is typically associated with DNA damage in the cytoplasm. Here, we reveal the existence of a pathway for oxidative stress in the envelope of Gram-negative bacteria. Stemming from the characterization of a poorly characterized gene, we found that HO• overproduction specifically in the envelope compartment causes inhibition of peptidoglycan synthesis and eventually bacterial cell lysis.
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44
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Identification of the potential active site of the septal peptidoglycan polymerase FtsW. PLoS Genet 2022; 18:e1009993. [PMID: 34986161 PMCID: PMC8765783 DOI: 10.1371/journal.pgen.1009993] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 01/18/2022] [Accepted: 12/14/2021] [Indexed: 11/19/2022] Open
Abstract
SEDS (Shape, Elongation, Division and Sporulation) proteins are widely conserved peptidoglycan (PG) glycosyltransferases that form complexes with class B penicillin-binding proteins (bPBPs, with transpeptidase activity) to synthesize PG during bacterial cell growth and division. Because of their crucial roles in bacterial morphogenesis, SEDS proteins are one of the most promising targets for the development of new antibiotics. However, how SEDS proteins recognize their substrate lipid II, the building block of the PG layer, and polymerize it into glycan strands is still not clear. In this study, we isolated and characterized dominant-negative alleles of FtsW, a SEDS protein critical for septal PG synthesis during bacterial cytokinesis. Interestingly, most of the dominant-negative FtsW mutations reside in extracellular loops that are highly conserved in the SEDS family. Moreover, these mutations are scattered around a central cavity in a modeled FtsW structure, which has been proposed to be the active site of SEDS proteins. Consistent with this, we found that these mutations blocked septal PG synthesis but did not affect FtsW localization to the division site, interaction with its partners nor its substrate lipid II. Taken together, these results suggest that the residues corresponding to the dominant-negative mutations likely constitute the active site of FtsW, which may aid in the design of FtsW inhibitors. SEDS (Shape, Elongation, Division and Sporulation) proteins are widely conserved peptidoglycan polymerases that play critical roles in cell elongation and cell division in rod-shaped bacteria. However, how they catalyze PG polymerization remains poorly understood. In this study, we isolated and characterized a set of dominant-negative mutations in the SEDS protein FtsW, which synthesizes septal peptidoglycan during cell division in most bacteria. Our results revealed that the dominant-negative mutations disrupt FtsW’s ability to synthesize peptidoglycan, but do not affect its other activities, suggesting that the corresponding amino acids may constitute the active site of FtsW.
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A High-Content Microscopy Screening Identifies New Genes Involved in Cell Width Control in Bacillus subtilis. mSystems 2021; 6:e0101721. [PMID: 34846166 PMCID: PMC8631317 DOI: 10.1128/msystems.01017-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
How cells control their shape and size is a fundamental question of biology. In most bacteria, cell shape is imposed by the peptidoglycan (PG) polymeric meshwork that surrounds the cell. Thus, bacterial cell morphogenesis results from the coordinated action of the proteins assembling and degrading the PG shell. Remarkably, during steady-state growth, most bacteria maintain a defined shape along generations, suggesting that error-proof mechanisms tightly control the process. In the rod-shaped model for the Gram-positive bacterium Bacillus subtilis, the average cell length varies as a function of the growth rate, but the cell diameter remains constant throughout the cell cycle and across growth conditions. Here, in an attempt to shed light on the cellular circuits controlling bacterial cell width, we developed a screen to identify genetic determinants of cell width in B. subtilis. Using high-content screening (HCS) fluorescence microscopy and semiautomated measurement of single-cell dimensions, we screened a library of ∼4,000 single knockout mutants. We identified 13 mutations significantly altering cell diameter, in genes that belong to several functional groups. In particular, our results indicate that metabolism plays a major role in cell width control in B. subtilis. IMPORTANCE Bacterial shape is primarily dictated by the external cell wall, a vital structure that, as such, is the target of countless antibiotics. Our understanding of how bacteria synthesize and maintain this structure is therefore a cardinal question for both basic and applied research. Bacteria usually multiply from generation to generation while maintaining their progenies with rigorously identical shapes. This implies that the bacterial cells constantly monitor and maintain a set of parameters to ensure this perpetuation. Here, our study uses a large-scale microscopy approach to identify at the whole-genome level, in a model bacterium, the genes involved in the control of one of the most tightly controlled cellular parameters, the cell width.
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Purification of infection-associated macropinosomes by magnetic isolation for proteomic characterization. Nat Protoc 2021; 16:5220-5249. [PMID: 34697468 DOI: 10.1038/s41596-021-00610-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 08/03/2021] [Indexed: 02/08/2023]
Abstract
Macropinocytosis refers to the nonselective uptake of extracellular molecules into many different types of eukaryotic cells within large fluid-filled vesicles named macropinosomes. Macropinosomes are relevant for a wide variety of cellular processes, such as antigen sampling in immune cells, homeostasis in the kidney, cell migration or pathogen uptake. Understanding the molecular composition of the different macropinosomes formed during these processes has helped to differentiate their regulations from other endocytic events. Here, we present a magnetic purification protocol that segregates scarce macropinosomes from other endocytic vesicles at a high purity and in a low-cost and unbiased manner. Our protocol takes advantage of moderate-sized magnetic beads of 100 nm in diameter coupled to mass-spectrometry-based proteomic analysis. Passing the cell lysate through a table-top magnet allows the quick retention of the bead-containing macropinosomes. Unlike other cell-fractionation-based methodologies, our protocol minimizes sample loss and production cost without prerequisite knowledge of the macropinosomes and with minimal laboratory experience. We describe a detailed procedure for the isolation of infection-associated macropinosomes during bacterial invasion and the optimization steps to readily adapt it to various studies. The protocol can be performed in 3 d to provide highly purified and enriched macropinosomes for qualitative proteomic composition analysis.
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Unipolar Peptidoglycan Synthesis in the Rhizobiales Requires an Essential Class A Penicillin-Binding Protein. mBio 2021; 12:e0234621. [PMID: 34544272 PMCID: PMC8546619 DOI: 10.1128/mbio.02346-21] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Members of the Rhizobiales are polarly growing bacteria that lack homologs of the canonical Rod complex. To investigate the mechanisms underlying polar cell wall synthesis, we systematically probed the function of cell wall synthesis enzymes in the plant pathogen Agrobacterium tumefaciens. The development of fluorescent d-amino acid dipeptide (FDAAD) probes, which are incorporated into peptidoglycan by penicillin-binding proteins in A. tumefaciens, enabled us to monitor changes in growth patterns in the mutants. Use of these fluorescent cell wall probes and peptidoglycan compositional analysis demonstrate that a single class A penicillin-binding protein is essential for polar peptidoglycan synthesis. Furthermore, we find evidence of an additional mode of cell wall synthesis that requires ld-transpeptidase activity. Genetic analysis and cell wall targeting antibiotics reveal that the mechanism of unipolar growth is conserved in Sinorhizobium and Brucella. This work provides insights into unipolar peptidoglycan biosynthesis employed by the Rhizobiales during cell elongation.
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Briggs NS, Bruce KE, Naskar S, Winkler ME, Roper DI. The Pneumococcal Divisome: Dynamic Control of Streptococcus pneumoniae Cell Division. Front Microbiol 2021; 12:737396. [PMID: 34737730 PMCID: PMC8563077 DOI: 10.3389/fmicb.2021.737396] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 09/15/2021] [Indexed: 12/14/2022] Open
Abstract
Cell division in Streptococcus pneumoniae (pneumococcus) is performed and regulated by a protein complex consisting of at least 14 different protein elements; known as the divisome. Recent findings have advanced our understanding of the molecular events surrounding this process and have provided new understanding of the mechanisms that occur during the division of pneumococcus. This review will provide an overview of the key protein complexes and how they are involved in cell division. We will discuss the interaction of proteins in the divisome complex that underpin the control mechanisms for cell division and cell wall synthesis and remodelling that are required in S. pneumoniae, including the involvement of virulence factors and capsular polysaccharides.
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Affiliation(s)
- Nicholas S. Briggs
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Kevin E. Bruce
- Department of Biology, Indiana University Bloomington, Bloomington, IN, United States
| | - Souvik Naskar
- Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Malcolm E. Winkler
- Department of Biology, Indiana University Bloomington, Bloomington, IN, United States
| | - David I. Roper
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
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Shao L, Liu Y, Tian X, Zou B, Zhao Y, Li X, Dai R. Global proteomic responses of sublethally injured Staphylococcus aureus induced by ohmic heating. Food Control 2021. [DOI: 10.1016/j.foodcont.2021.108106] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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The LpoA activator is required to stimulate the peptidoglycan polymerase activity of its cognate cell wall synthase PBP1a. Proc Natl Acad Sci U S A 2021; 118:2108894118. [PMID: 34429361 PMCID: PMC8536351 DOI: 10.1073/pnas.2108894118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A cell wall made of the heteropolymer peptidoglycan (PG) surrounds most bacterial cells. This essential surface layer is required to prevent lysis from internal osmotic pressure. The class A penicillin-binding proteins (aPBPs) play key roles in building the PG network. These bifunctional enzymes possess both PG glycosyltransferase (PGT) and transpeptidase (TP) activity to polymerize the wall glycans and cross-link them, respectively. In Escherichia coli and other gram-negative bacteria, aPBP function is dependent on outer membrane lipoproteins. The lipoprotein LpoA activates PBP1a and LpoB promotes PBP1b activity. In a purified system, the major effect of LpoA on PBP1a is TP stimulation. However, the relevance of this activation to the cellular function of LpoA has remained unclear. To better understand why PBP1a requires LpoA for its activity in cells, we identified variants of PBP1a from E. coli and Pseudomonas aeruginosa that function in the absence of the lipoprotein. The changes resulting in LpoA bypass map to the PGT domain and the linker region between the two catalytic domains. Purification of the E. coli variants showed that they are hyperactivated for PGT but not TP activity. Furthermore, in vivo analysis found that LpoA is necessary for the glycan synthesis activity of PBP1a in cells. Thus, our results reveal that LpoA exerts a much greater control over the cellular activity of PBP1a than previously appreciated. It not only modulates PG cross-linking but is also required for its cognate synthase to make PG glycans in the first place.
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