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Jang H, Kim CM, Ha HJ, Hong E, Park HH. Interdomain flexibility and putative active site was revealed by crystal structure of MltG from Acinetobacter baumannii. Biochem Biophys Res Commun 2024; 727:150318. [PMID: 38945066 DOI: 10.1016/j.bbrc.2024.150318] [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: 06/23/2024] [Revised: 06/24/2024] [Accepted: 06/26/2024] [Indexed: 07/02/2024]
Abstract
MltG, positioned within the inner membrane of bacteria, functions as a lytic transglycosylase (LT) essential for integrating into the cell wall by cleaving the newly synthesized glycan strand, emphasizing its critical involvement in bacterial cell wall biosynthesis and remodeling. Current study reported the first structure of MltG family of LT. We have elucidated the structure of MltG from Acinetobacter baumannii (abMltG), a formidable superbug renowned for its remarkable antibiotic resistance. Our structural and biochemical investigations unveiled the presence of a flexible peptidoglycan (PG)-binding domain (PGD) within MltG family, which exists as a monomer in solution. Furthermore, we delineated the putative active site of abMltG via a combination of structural analysis and sequence comparison. This discovery enhances our comprehension of the transglycosylation process mediated by the MltG family, offering insights that could inform the development of novel antibiotics tailored to combat A. baumannii.
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Affiliation(s)
- Hyunseok Jang
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea; Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Chang Min Kim
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Hyun Ji Ha
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea; Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Eunmi Hong
- New Drug Development Center, Daegu-Gyeongbuk Medical Innovation Foundation, Daegu, 41061, Republic of Korea
| | - Hyun Ho Park
- College of Pharmacy, Chung-Ang University, Seoul, 06974, Republic of Korea; Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul, 06974, Republic of Korea.
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2
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du Preez LL, van der Walt E, Valverde A, Rothmann C, Neser FWC, Cason ED. A metagenomic survey of the fecal microbiome of the African savanna elephant (Loxodonta africana). Anim Genet 2024; 55:621-643. [PMID: 38923598 DOI: 10.1111/age.13458] [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: 03/08/2024] [Revised: 06/06/2024] [Accepted: 06/06/2024] [Indexed: 06/28/2024]
Abstract
The African savanna elephant (Loxodonta africana) is the largest terrestrial animal on Earth and is found primarily in Southern and Eastern Africa. It is a hindgut, colonic fermenter and subsists on a diet of raw plant materials found in its grazing area. In this study the bacterial, archaeal and fungal populations of seven African savanna elephant fecal metagenomes were first characterized using amplicon sequencing. On the genus level it was observed that the p-1088-a5 gut group in the bacteriome, Methanocorpusulum and Methanobrevibacter in the archaeome and Alternaria, Aurobasidium, Didymella and Preussia in the mycome, predominated. Subsequently, metagenomic shotgun sequencing was employed to identify possible functional pathways and carbohydrate-active enzymes (CAZymes). Carbohydrate catabolic pathways represented the main degradation pathways, and the fecal metagenome was enriched in the glycohydroside (GH) class of CAZymes. Additionally, the top GH families identified - GH43, GH2, GH13 and GH3 - are known to be associated with cellulytic, hemicellulytic and pectolytic activities. Finally, the CAZymes families identified in the African savanna elephant were compared with those found in the Asian elephant and it was demonstrated that there is a unique repository of CAZymes that could be leveraged in the biotechnological context such as the degradation of lignocellulose for the production of second-generation biofuels and energy.
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Affiliation(s)
- Louis Lategan du Preez
- Department of Animal Science, University of the Free State, Bloemfontein, Free State, South Africa
| | - Elzette van der Walt
- Department of Microbiology and Biochemistry, University of the Free State, Bloemfontein, Free State, South Africa
| | - Angel Valverde
- Department of Microbiology and Biochemistry, University of the Free State, Bloemfontein, Free State, South Africa
- Instituto de Recursos Naturales y Agrobiología de Salamanca, Consejo Superior de Investigaciones Científicas, Salamanca, Spain
| | - Christopher Rothmann
- Department of Animal Science, University of the Free State, Bloemfontein, Free State, South Africa
- Department of Microbiology and Biochemistry, University of the Free State, Bloemfontein, Free State, South Africa
| | | | - Errol Duncan Cason
- Department of Animal Science, University of the Free State, Bloemfontein, Free State, South Africa
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Miguel-Ruano V, Feltzer R, Batuecas MT, Ramachandran B, El-Araby AM, Avila-Cobian LF, De Benedetti S, Mobashery S, Hermoso JA. Structural characterization of lytic transglycosylase MltD of Pseudomonas aeruginosa, a target for the natural product bulgecin A. Int J Biol Macromol 2024; 267:131420. [PMID: 38583835 PMCID: PMC11327851 DOI: 10.1016/j.ijbiomac.2024.131420] [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: 01/02/2024] [Revised: 04/01/2024] [Accepted: 04/04/2024] [Indexed: 04/09/2024]
Abstract
Natural product bulgecin A potentiates the activity of β-lactam antibiotics by inhibition of three lytic transglycosylases in Pseudomonas aeruginosa, of which MltD is one. MltD exhibits both endolytic and exolytic reactions in the turnover of the cell-wall peptidoglycan and tolerates the presence or absence of stem peptides in its substrates. The present study reveals structural features of the multimodular MltD, presenting a catalytic module and four cell-wall-binding LysM modules that account for these attributes. Three X-ray structures are reported herein for MltD that disclose one unpredicted LysM module tightly attached to the catalytic domain, whereas the other LysM modules are mobile, and connected to the catalytic domain through long flexible linkers. The formation of crystals depended on the presence of bulgecin A. The expansive active-site cleft is highlighted by the insertion of a helical region, a hallmark of the family 1D of lytic transglycosylases, which was mapped out in a ternary complex of MltD:bulgecinA:chitotetraose, revealing at the minimum the presence of eight subsites (from -4 to +4, with the seat of reaction at subsites -1 and + 1) for binding of sugars of the substrate for the endolytic reaction. The mechanism of the exolytic reaction is revealed in one of the structures, showing how the substrate's terminal anhydro-NAM moiety could be sequestered at subsite +2. Our results provide the structural insight for both the endolytic and exolytic activities of MltD during cell-wall-turnover events.
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Affiliation(s)
- Vega Miguel-Ruano
- Department of Crystallography and Structural Biology, Instituto de Química-Física "Blas Cabrera", Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Rhona Feltzer
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - María T Batuecas
- Department of Crystallography and Structural Biology, Instituto de Química-Física "Blas Cabrera", Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Balajee Ramachandran
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Amr M El-Araby
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Luis F Avila-Cobian
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Stefania De Benedetti
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
| | - Juan A Hermoso
- Department of Crystallography and Structural Biology, Instituto de Química-Física "Blas Cabrera", Consejo Superior de Investigaciones Científicas, Madrid, Spain.
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Liu X, den Blaauwen T. NlpI-Prc Proteolytic Complex Mediates Peptidoglycan Synthesis and Degradation via Regulation of Hydrolases and Synthases in Escherichia coli. Int J Mol Sci 2023; 24:16355. [PMID: 38003545 PMCID: PMC10671308 DOI: 10.3390/ijms242216355] [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: 10/16/2023] [Revised: 11/09/2023] [Accepted: 11/13/2023] [Indexed: 11/26/2023] Open
Abstract
Balancing peptidoglycan (PG) synthesis and degradation with precision is essential for bacterial growth, yet our comprehension of this intricate process remains limited. The NlpI-Prc proteolytic complex plays a crucial but poorly understood role in the regulation of multiple enzymes involved in PG metabolism. In this paper, through fluorescent D-amino acid 7-hydroxycoumarincarbonylamino-D-alanine (HADA) labeling and immunolabeling assays, we have demonstrated that the NlpI-Prc complex regulates the activity of PG transpeptidases and subcellular localization of PBP3 under certain growth conditions. PBP7 (a PG hydrolase) and MltD (a lytic transglycosylase) were confirmed to be negatively regulated by the NlpI-Prc complex by an in vivo degradation assay. The endopeptidases, MepS, MepM, and MepH, have consistently been demonstrated as redundantly essential "space makers" for nascent PG insertion. However, we observed that the absence of NlpI-Prc complex can alleviate the lethality of the mepS mepM mepH mutant. A function of PG lytic transglycosylases MltA and MltD as "space makers" was proposed through multiple gene deletions. These findings unveil novel roles for NlpI-Prc in the regulation of both PG synthesis and degradation, shedding light on the previously undiscovered function of lytic transglycosylases as "space makers" in PG expansion.
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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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Ashy RA, Jalal RS, Sonbol HS, Alqahtani MD, Sefrji FO, Alshareef SA, Alshehrei FM, Abuauf HW, Baz L, Tashkandi MA, Hakeem IJ, Refai MY, Abulfaraj AA. Functional annotation of rhizospheric phageome of the wild plant species Moringa oleifera. Front Microbiol 2023; 14:1166148. [PMID: 37260683 PMCID: PMC10227523 DOI: 10.3389/fmicb.2023.1166148] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 04/10/2023] [Indexed: 06/02/2023] Open
Abstract
Introduction The study aims to describe phageome of soil rhizosphere of M.oleifera in terms of the genes encoding CAZymes and other KEGG enzymes. Methods Genes of the rhizospheric virome of the wild plant species Moringa oleifera were investigated for their ability to encode useful CAZymes and other KEGG (Kyoto Encyclopedia of Genes and Genomes) enzymes and to resist antibiotic resistance genes (ARGs) in the soil. Results Abundance of these genes was higher in the rhizospheric microbiome than in the bulk soil. Detected viral families include the plant viral family Potyviridae as well as the tailed bacteriophages of class Caudoviricetes that are mainly associated with bacterial genera Pseudomonas, Streptomyces and Mycobacterium. Viral CAZymes in this soil mainly belong to glycoside hydrolase (GH) families GH43 and GH23. Some of these CAZymes participate in a KEGG pathway with actions included debranching and degradation of hemicellulose. Other actions include biosynthesizing biopolymer of the bacterial cell wall and the layered cell wall structure of peptidoglycan. Other CAZymes promote plant physiological activities such as cell-cell recognition, embryogenesis and programmed cell death (PCD). Enzymes of other pathways help reduce the level of soil H2O2 and participate in the biosynthesis of glycine, malate, isoprenoids, as well as isoprene that protects plant from heat stress. Other enzymes act in promoting both the permeability of bacterial peroxisome membrane and carbon fixation in plants. Some enzymes participate in a balanced supply of dNTPs, successful DNA replication and mismatch repair during bacterial cell division. They also catalyze the release of signal peptides from bacterial membrane prolipoproteins. Phages with the most highly abundant antibiotic resistance genes (ARGs) transduce species of bacterial genera Pseudomonas, Streptomyces, and Mycobacterium. Abundant mechanisms of antibiotic resistance in the rhizosphere include "antibiotic efflux pump" for ARGs soxR, OleC, and MuxB, "antibiotic target alteration" for parY mutant, and "antibiotic inactivation" for arr-1. Discussion These ARGs can act synergistically to inhibit several antibiotics including tetracycline, penam, cephalosporin, rifamycins, aminocoumarin, and oleandomycin. The study highlighted the issue of horizontal transfer of ARGs to clinical isolates and human gut microbiome.
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Affiliation(s)
- Ruba A. Ashy
- Department of Biology, College of Science, University of Jeddah, Jeddah, Saudi Arabia
| | - Rewaa S. Jalal
- Department of Biology, College of Science, University of Jeddah, Jeddah, Saudi Arabia
| | - Hana S. Sonbol
- Department of Biology, College of Sciences, Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia
| | - Mashael D. Alqahtani
- Department of Biology, College of Sciences, Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia
| | - Fatmah O. Sefrji
- Department of Biology, College of Science, Taibah University, Al-Madinah Al-Munawwarah, Saudi Arabia
| | - Sahar A. Alshareef
- Department of Biology, College of Science and Arts at Khulis, University of Jeddah, Jeddah, Saudi Arabia
| | - Fatimah M. Alshehrei
- Department of Biology, Jumum College University, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Haneen W. Abuauf
- Department of Biology, Faculty of Applied Science, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Lina Baz
- Department of Biochemistry, Faculty of Science, King AbdulAziz University, Jeddah, Saudi Arabia
| | - Manal A. Tashkandi
- Department of Biochemistry, College of Science, University of Jeddah, Jeddah, Saudi Arabia
| | - Israa J. Hakeem
- Department of Biochemistry, College of Science, University of Jeddah, Jeddah, Saudi Arabia
| | - Mohammed Y. Refai
- Department of Biochemistry, College of Science, University of Jeddah, Jeddah, Saudi Arabia
| | - Aala A. Abulfaraj
- Biological Sciences Department, College of Science & Arts, King AbdulAziz University, Rabigh, Saudi Arabia
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6
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Alrafaie AM, Stafford GP. Enterococcal bacteriophage: A survey of the tail associated lysin landscape. Virus Res 2023; 327:199073. [PMID: 36787848 DOI: 10.1016/j.virusres.2023.199073] [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: 10/12/2022] [Revised: 02/05/2023] [Accepted: 02/10/2023] [Indexed: 02/16/2023]
Abstract
Bacteriophages are viruses that exclusively infect bacteria which require local degradation of cell barriers. This degradation is accomplished by various lysins located mainly within the phage tail structure. In this paper we surveyed and analysed the genomes of 506 isolated bacteriophage and prophage infecting or harboured within the genomes of the medically important Enterococcus faecalis and faecium. We highlight and characterise the major features of the genomes of phage in the morphological groups podovirus, siphovirus and myovirus, and explore their categorisation according to the new ICTV classifications, with a focus on putative extracellular lysins chiefly within tail modules. Our analysis reveals a range of potential cell-wall targeting enzyme domains that are part of tail, tape measure or other predicted base structures of these phages or prophages. These largely fall into protein domains targeting pentapeptide or glycosidic linkages within peptidoglycan but also potentially the enterococcal polysaccharide antigen (EPA) and wall teichoic acids of these species (i.e., Pectinesterases and Phosphodiesterases). Notably, there is a great variety of domain architectures that reveal the diversity of evolutionary solutions to attack the Enterococcus cell wall. Despite this variety, most phage and prophage possess a putative endopeptidase (70%), reflecting the ubiquity of this cell surface barrier. We also identified a predicted lytic transglycosylase domain belonging to the glycosyl hydrolase (GH) family 23 and present exclusively within tape measure proteins. Our data also reveal distinct features of the genomes of podo-, sipho- and myo-type viruses that most likely relate to their size and complexity. Overall, we lay a foundation for expression of recombinant TAL proteins and engineering of enterococcal and other phage that will be invaluable for researchers in this field.
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Affiliation(s)
- Alhassan M Alrafaie
- Integrated BioSciences, School of Clinical Dentistry, University of Sheffield, Sheffield, United Kingdom; Department of Medical Laboratory Sciences, College of Applied Medical Sciences in Al-Kharj, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia.
| | - Graham P Stafford
- Integrated BioSciences, School of Clinical Dentistry, University of Sheffield, Sheffield, United Kingdom.
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Gao P, Fan K, Zhang G, Yin X, Jia C, Tian H. Coal-mining subsidence changed distribution of the microbiomes and their functional genes in a farmland. J Basic Microbiol 2023; 63:542-557. [PMID: 36646520 DOI: 10.1002/jobm.202200582] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/19/2022] [Accepted: 01/02/2023] [Indexed: 01/18/2023]
Abstract
Land subsidence is a serious geological event, and can trigger severe environmental and ecological issues. In this study, the influences of coal-mining subsidence on distribution of farmland microbiomes and their functional genes were investigated by 16 S ribosomal RNA (rRNA) gene and metagenome sequencing. The results showed the existence of a core microbiome, which determined the community compositions across the subsidence farmland. Subsidence decreased the relative abundances of dominant Streptomyces, Nocardioides, and Rhizophagus, but increased the relative abundances of dominant Bradyrhizobium, Rhizobium, and Trichoderma. Subsidence also decreased the relative abundances of genes related to carbon metabolism, Quorum sensing, aminoacyl-transfer RNA (tRNA) biosynthesis, and oxidative phosphorylation, and increased the relative abundances of genes related to two-component system and bacterial chemotaxis. Furthermore, subsidence weakened the biosynthesis of organic carbons by decreasing the relative abundances of genes encoding glycosyl transferases, and strengthened decomposition of degradable organic carbons of the microbiomes and auxiliary activities by increasing the relative abundances of genes encoding glycoside hydrolases and polysaccharide lyases. The concentrations of total phosphorus, Mg2+ , and Ca2+ at the lower areas were significantly higher than those at the upper areas, indicating an associated loss of soil nutrients. Canonical correspondence analysis showed that soil moisture, pH, and the concentrations of NH4 + and Ca2+ were the main factors affecting the distribution of the microbiomes and their functional genes. Collectively, this study shows that coal-mining subsidence alters soil physicochemical properties and distribution of farmland microbiomes and their functional genes.
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Affiliation(s)
- Peike Gao
- College of Life Sciences, Qufu Normal University, Qufu, Shandong, China
| | - Keyan Fan
- College of Life Sciences, Qufu Normal University, Qufu, Shandong, China
| | - Guoquan Zhang
- Technology Innovation Center of Restoration and Reclamation in Mining induced Subsidence Land, Ministry of Natural Resources, China.,Shandong Provincial Lunan Geology and Exploration Institute (Shandong Provincial Bureau of Geology and Mineral Resources No.2 Geological Brigade), Jining, Shandong, China
| | - Xiaohui Yin
- College of Life Sciences, Qufu Normal University, Qufu, Shandong, China
| | - Chuanxing Jia
- College of Life Sciences, Qufu Normal University, Qufu, Shandong, China.,Technology Innovation Center of Restoration and Reclamation in Mining induced Subsidence Land, Ministry of Natural Resources, China
| | - Huimei Tian
- College of Forestry, Shandong Agricultural University, Tai'an, Shandong, China
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Dede B, Hansen CT, Neuholz R, Schnetger B, Kleint C, Walker S, Bach W, Amann R, Meyerdierks A. Niche differentiation of sulfur-oxidizing bacteria (SUP05) in submarine hydrothermal plumes. THE ISME JOURNAL 2022; 16:1479-1490. [PMID: 35082431 PMCID: PMC9123188 DOI: 10.1038/s41396-022-01195-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 01/03/2022] [Accepted: 01/10/2022] [Indexed: 11/09/2022]
Abstract
Hydrothermal plumes transport reduced chemical species and metals into the open ocean. Despite their considerable spatial scale and impact on biogeochemical cycles, niche differentiation of abundant microbial clades is poorly understood. Here, we analyzed the microbial ecology of two bathy- (Brothers volcano; BrV-cone and northwest caldera; NWC) and a mesopelagic (Macauley volcano; McV) plumes on the Kermadec intra-oceanic arc in the South Pacific Ocean. The microbial community structure, determined by a combination of 16S rRNA gene, fluorescence in situ hybridization and metagenome analysis, was similar to the communities observed in other sulfur-rich plumes. This includes a dominance of the vent characteristic SUP05 clade (up to 22% in McV and 51% in BrV). In each of the three plumes analyzed, the community was dominated by a different yet uncultivated chemoautotrophic SUP05 species, here, provisionally named, Candidatus Thioglobus vadi (McV), Candidatus Thioglobus vulcanius (BrV-cone) and Candidatus Thioglobus plumae (BrV-NWC). Statistical analyses, genomic potential and mRNA expression profiles suggested a SUP05 niche partitioning based on sulfide and iron concentration as well as water depth. A fourth SUP05 species was present at low frequency throughout investigated plume samples and may be capable of heterotrophic or mixotrophic growth. Taken together, we propose that small variations in environmental parameters and depth drive SUP05 niche partitioning in hydrothermal plumes.
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Affiliation(s)
- Bledina Dede
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Christian T Hansen
- MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Rene Neuholz
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
- Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM), Group: Quality Assurance and Cyber-Physical Systems, Bremen, Germany
| | - Bernhard Schnetger
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Charlotte Kleint
- MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
- Department of Physics and Earth Sciences, Jacobs University Bremen, Bremen, Germany
| | - Sharon Walker
- National Oceanic and Atmospheric Administration, Pacific Marine Environmental Laboratory, Seattle, WA, USA
| | - Wolfgang Bach
- MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
- Geoscience Department, University of Bremen, Bremen, Germany
| | - Rudolf Amann
- Max Planck Institute for Marine Microbiology, Bremen, Germany
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Hernández R, Chaib De Mares M, Jimenez H, Reyes A, Caro-Quintero A. Functional and Phylogenetic Characterization of Bacteria in Bovine Rumen Using Fractionation of Ruminal Fluid. Front Microbiol 2022; 13:813002. [PMID: 35401437 PMCID: PMC8992543 DOI: 10.3389/fmicb.2022.813002] [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: 11/11/2021] [Accepted: 02/01/2022] [Indexed: 01/08/2023] Open
Abstract
Cattle productivity depends on our ability to fully understand and manipulate the fermentation process of plant material that occurs in the bovine rumen, which ultimately leads to the improvement of animal health and increased productivity with a reduction in environmental impact. An essential step in this direction is the phylogenetic and functional characterization of the microbial species composing the ruminal microbiota. To address this challenge, we separated a ruminal fluid sample by size and density using a sucrose density gradient. We used the full sample and the smallest fraction (5%), allowing the enrichment of bacteria, to assemble metagenome-assembled genomes (MAGs). We obtained a total of 16 bacterial genomes, 15 of these enriched in the smallest fraction of the gradient. According to the recently proposed Genome Taxonomy Database (GTDB) taxonomy, these MAGs belong to Bacteroidota, Firmicutes_A, Firmicutes, Proteobacteria, and Spirochaetota phyla. Fifteen MAGs were novel at the species level and four at the genus level. The functional characterization of these MAGs suggests differences from what is currently known from the genomic potential of well-characterized members from this complex environment. Species of the phyla Bacteroidota and Spirochaetota show the potential for hydrolysis of complex polysaccharides in the plant cell wall and toward the production of B-complex vitamins and protein degradation in the rumen. Conversely, the MAGs belonging to Firmicutes and Alphaproteobacteria showed a reduction in several metabolic pathways; however, they have genes for lactate fermentation and the presence of hydrolases and esterases related to chitin degradation. Our results demonstrate that the separation of the rumen microbial community by size and density reduced the complexity of the ruminal fluid sample and enriched some poorly characterized ruminal bacteria allowing exploration of their genomic potential and their functional role in the rumen ecosystem.
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Affiliation(s)
- Ruth Hernández
- Max Planck Tandem Group in Computational Biology, Department of Biological Sciences, Universidad de los Andes, Bogotá, Colombia
| | - Maryam Chaib De Mares
- Max Planck Tandem Group in Computational Biology, Department of Biological Sciences, Universidad de los Andes, Bogotá, Colombia
| | - Hugo Jimenez
- Animal Microbiology Laboratory, Agrodiversity Department, Corporación Colombiana de Investigación Agropecuaria - AGROSAVIA, Bogotá, Colombia
| | - Alejandro Reyes
- Max Planck Tandem Group in Computational Biology, Department of Biological Sciences, Universidad de los Andes, Bogotá, Colombia.,The Edison Family Center for Genome Science and Systems Biology, Washington University School of Medicine, Saint Louis, MO, United States
| | - Alejandro Caro-Quintero
- Departamento de Biología, Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia
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10
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In silico characterization of molecular factors involved in metabolism and pathogenicity of Phytophthora cinnamomi. Mol Biol Rep 2021; 49:1463-1473. [PMID: 34751913 DOI: 10.1007/s11033-021-06901-0] [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: 10/24/2020] [Accepted: 10/29/2021] [Indexed: 10/19/2022]
Abstract
Phytophthora cinnamomi is classified as one of the most devastating plant pathogens in the world. It has a destructive effect on more than 5000 horticultural and forestry species in the world, and especially on Castanea sativa. The genus Phytophthora belongs to the Class Oomycetes, a group of fungus like organisms which provoke plant diseases via motile zoospores. Control of this organism is considered very challenging because of the limited range of effective chemical inhibitors. The development of sustainable control measures for the future management of P. cinnamomi requires in-depth knowledge of the cellular and molecular bases of development and metabolism. The aim of this review was to identify molecular factors associated with the metabolism of P. cinnamomi by studying the genes implicated in fundamental metabolism using tools of bioinformatics. Also, some genes involved in pathogenicity will be cited and characterized, such as genes coding for transglycosylases. Genomic sequences of P. cinnamomi were analyzed using an open reading frame (ORF) finder. The identified ORFs products (proteins) were compared to sequences already described and with known functions present in databases such as NCBI and fungi database. In this way, homologous proteins were found, with the respective specific domains, to proteins involved in the metabolism and pathogenicity of Phytophthora ssp.
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11
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Jang H, Do H, Kim CM, Kim GE, Lee JH, Park HH. Molecular basis of dimerization of lytic transglycosylase revealed by the crystal structure of MltA from Acinetobacter baumannii. IUCRJ 2021; 8:921-930. [PMID: 34804545 PMCID: PMC8562663 DOI: 10.1107/s2052252521008666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 08/18/2021] [Indexed: 06/13/2023]
Abstract
Peptidoglycan digestion by murein-degrading enzymes is a critical process in bacterial cell growth and/or cell division. The membrane-bound lytic murein transglycosylase A (MltA) is a murein-degrading enzyme; it catalyzes the cleavage of the β-1,4-glycosidic linkage between N-acetylmuramic acid and N-acetylglucosamine in peptidoglycans. Although substrate recognition and cleavage by MltA have been examined by previous structural and mutagenesis studies, the overall mechanism of MltA in conjunction with other functionally related molecules on the outer membrane of bacterial cells for peptidoglycan degradation has remained elusive. In this study, the crystal structure of MltA from the virulent human pathogen Acinetobacter baumannii is characterized and presented. The study indicated that MltA from A. baumannii forms homodimers via an extra domain which is specific to this species. Furthermore, the working mechanism of MltA with various functionally related proteins on the bacterial outer membrane was modeled based on the structural and biochemical analysis.
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Affiliation(s)
- Hyunseok Jang
- College of Pharmacy, Chung-Ang University, Seoul 06974, Republic of Korea
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul 06974, Republic of Korea
| | - Hackwon Do
- Unit of Research for Practical Application, Korea Polar Research Institute, Incheon 21990, Republic of Korea
- Department of Polar Sciences, University of Science and Technology, Incheon 21990, Republic of Korea
| | - Chang Min Kim
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul 06974, Republic of Korea
| | - Gi Eob Kim
- College of Pharmacy, Chung-Ang University, Seoul 06974, Republic of Korea
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul 06974, Republic of Korea
| | - Jun Hyuck Lee
- Unit of Research for Practical Application, Korea Polar Research Institute, Incheon 21990, Republic of Korea
- Department of Polar Sciences, University of Science and Technology, Incheon 21990, Republic of Korea
| | - Hyun Ho Park
- College of Pharmacy, Chung-Ang University, Seoul 06974, Republic of Korea
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul 06974, Republic of Korea
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12
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Xu H, Hu B, Flesher DA, Liu J, Motaleb MA. BB0259 Encompasses a Peptidoglycan Lytic Enzyme Function for Proper Assembly of Periplasmic Flagella in Borrelia burgdorferi. Front Microbiol 2021; 12:692707. [PMID: 34659138 PMCID: PMC8517470 DOI: 10.3389/fmicb.2021.692707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 08/19/2021] [Indexed: 11/18/2022] Open
Abstract
Assembly of the bacterial flagellar rod, hook, and filament requires penetration through the peptidoglycan (PG) sacculus and outer membrane. In most β- and γ-proteobacteria, the protein FlgJ has two functional domains that enable PG hydrolyzing activity to create pores, facilitating proper assembly of the flagellar rod. However, two distinct proteins performing the same functions as the dual-domain FlgJ are proposed in δ- and ε-proteobacteria as well as spirochetes. The Lyme disease spirochete Borrelia burgdorferi genome possesses a FlgJ and a PG lytic SLT enzyme protein homolog (BB0259). FlgJ in B. burgdorferi is crucial for flagellar hook and filament assembly but not for the proper rod assembly reported in other bacteria. However, BB0259 has never been characterized. Here, we use cryo-electron tomography to visualize periplasmic flagella in different bb0259 mutant strains and provide evidence that the E580 residue of BB0259 is essential for PG-hydrolyzing activity. Without the enzyme activity, the flagellar hook fails to penetrate through the pores in the cell wall to complete assembly of an intact periplasmic flagellum. Given that FlgJ and BB0259 interact with each other, they likely coordinate the penetration through the PG sacculus and assembly of a functional flagellum in B. burgdorferi and other spirochetes. Because of its role, we renamed BB0259 as flagellar-specific lytic transglycosylase or LTaseBb.
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Affiliation(s)
- Hui Xu
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
| | - Bo Hu
- Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - David A. Flesher
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, United States
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, United States
| | - Jun Liu
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, United States
- Microbial Sciences Institute, Yale University, West Haven, CT, United States
| | - Md A. Motaleb
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC, United States
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13
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Structural changes in bacteriophage T7 upon receptor-induced genome ejection. Proc Natl Acad Sci U S A 2021; 118:2102003118. [PMID: 34504014 DOI: 10.1073/pnas.2102003118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/29/2021] [Indexed: 12/11/2022] Open
Abstract
Many tailed bacteriophages assemble ejection proteins and a portal-tail complex at a unique vertex of the capsid. The ejection proteins form a transenvelope channel extending the portal-tail channel for the delivery of genomic DNA in cell infection. Here, we report the structure of the mature bacteriophage T7, including the ejection proteins, as well as the structures of the full and empty T7 particles in complex with their cell receptor lipopolysaccharide. Our near-atomic-resolution reconstruction shows that the ejection proteins in the mature T7 assemble into a core, which comprises a fourfold gene product 16 (gp16) ring, an eightfold gp15 ring, and a putative eightfold gp14 ring. The gp15 and gp16 are mainly composed of helix bundles, and gp16 harbors a lytic transglycosylase domain for degrading the bacterial peptidoglycan layer. When interacting with the lipopolysaccharide, the T7 tail nozzle opens. Six copies of gp14 anchor to the tail nozzle, extending the nozzle across the lipopolysaccharide lipid bilayer. The structures of gp15 and gp16 in the mature T7 suggest that they should undergo remarkable conformational changes to form the transenvelope channel. Hydrophobic α-helices were observed in gp16 but not in gp15, suggesting that gp15 forms the channel in the hydrophilic periplasm and gp16 forms the channel in the cytoplasmic membrane.
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14
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Xu J, Xu R, Jia M, Su Y, Zhu W. Metatranscriptomic analysis of colonic microbiota's functional response to different dietary fibers in growing pigs. Anim Microbiome 2021; 3:45. [PMID: 34217374 PMCID: PMC8254964 DOI: 10.1186/s42523-021-00108-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 06/23/2021] [Indexed: 01/30/2023] Open
Abstract
Background Dietary fibers are widely considered to be beneficial to health as they produce nutrients through gut microbial fermentation while facilitating weight management and boosting gut health. To date, the gene expression profiles of the carbohydrate active enzymes (CAZymes) that respond to different types of fibers (raw potato starch, RPS; inulin, INU; pectin, PEC) in the gut microbes of pigs are not well understood. Therefore, we investigated the functional response of colonic microbiota to different dietary fibers in pigs through metatranscriptomic analysis. Results The results showed that the microbial composition and CAZyme structure of the three experimental groups changed significantly compared with the control group (CON). Based on a comparative analysis with the control diet, RPS increased the abundance of Parabacteroides, Ruminococcus, Faecalibacterium and Alloprevotella but decreased Sutterella; INU increased the relative abundance of Fusobacterium and Rhodococcus but decreased Bacillus; and PEC increased the relative abundance of the Streptococcus and Bacteroidetes groups but decreased Clostridium, Clostridioides, Intestinibacter, Gemmiger, Muribaculum and Vibrio. The gene expression of CAZymes GH8, GH14, GH24, GH38, GT14, GT31, GT77 and GT91 downregulated but that of GH77, GH97, GT3, GT10 and GT27 upregulated in the RPS diet group; the gene expression of AA4, AA7, GH14, GH15, GH24, GH26, GH27, GH38, GH101, GT26, GT27 and GT38 downregulated in the INU group; and the gene expression of PL4, AA1, GT32, GH18, GH37, GH101 and GH112 downregulated but that of CE14, AA3, AA12, GH5, GH102 and GH103 upregulated in the PEC group. Compared with the RPS and INU groups, the composition of colonic microbiota in the PEC group exhibited more diverse changes with the variation of CAZymes and Streptococcus as the main contributor to CBM61, which greatly promoted the digestion of pectin. Conclusion The results of this exploratory study provided a comprehensive overview of the effects of different fibers on nutrient digestibility, gut microbiota and CAZymes in pig colon, which will furnish new insights into the impacts of the use of dietary fibers on animal and human health. Supplementary Information The online version contains supplementary material available at 10.1186/s42523-021-00108-1.
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Affiliation(s)
- Jie Xu
- Laboratory of Gastrointestinal Microbiology, Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095, China.,National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing, 210095, China
| | - Rongying Xu
- Laboratory of Gastrointestinal Microbiology, Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095, China.,National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing, 210095, China
| | - Menglan Jia
- Laboratory of Gastrointestinal Microbiology, Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095, China.,National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yong Su
- Laboratory of Gastrointestinal Microbiology, Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095, China. .,National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Weiyun Zhu
- Laboratory of Gastrointestinal Microbiology, Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095, China.,National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, Nanjing, 210095, China
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15
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Basit A, Qadir S, Qureshi S, Rehman SU. Cloning and expression analysis of fused holin-endolysin from RL bacteriophage; Exhibits broad activity against multi drug resistant pathogens. Enzyme Microb Technol 2021; 149:109846. [PMID: 34311883 DOI: 10.1016/j.enzmictec.2021.109846] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 06/02/2021] [Accepted: 06/06/2021] [Indexed: 01/20/2023]
Abstract
Antibiotic resistance has become a major risk to community health over last few years because of antibiotics overuse around the globe and lack of new antibiotics development. Phages and their lytic enzymes are considered as an effective alternative of antibiotics to control drug resistant bacterial pathogens. Endolysins prove to be a promising class of antibacterials due to their specificity and less chances of resistance development in bacterial pathogens. Though large number of endolysins has been reported against gram positive bacteria, very few reported against gram negative bacteria due to the presence of outer membrane, which acts as physical barrier against endolysin attack to peptidoglycan. In the current study, we have expressed endolysin (RL_Lys) and holin fused at the N terminus of endolysin (RL_Hlys) from RL phage infecting multi drug resistant (MDR) Pseudomonas aeruginosa. Both endolysin variants were found active against wide range of MDR strains P. aeruginosa, Klebsella pneumonia, Salmonella Sp. and Methicillin Resistant Staphylococcus aureus (MRSA). Broth reduction assay showed that RL_Hlys is more active than RL_Lys due to presence of holin, which assist the endolysin access towards cell wall. The protein ligand docking and molecular dynamic simulation results showed that C- terminus region of endolysin play vital role in cell wall binding and even in the absence of holin, hydrolyze a broad range of gram negative bacterial pathogens. The significant activity of RL-Lys and RL_Hlys against a broad range of MDR gram negative and positive bacterial pathogens makes them good candidates for antibiotic alternatives.
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Affiliation(s)
- Abdul Basit
- Institute of Microbiology and Molecular Genetics, University of the Punjab, Lahore, 54590, Pakistan.
| | - Sania Qadir
- Institute of Microbiology and Molecular Genetics, University of the Punjab, Lahore, 54590, Pakistan.
| | - Sara Qureshi
- Institute of Microbiology and Molecular Genetics, University of the Punjab, Lahore, 54590, Pakistan.
| | - Shafiq Ur Rehman
- Institute of Microbiology and Molecular Genetics, University of the Punjab, Lahore, 54590, Pakistan.
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16
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Garde S, Chodisetti PK, Reddy M. Peptidoglycan: Structure, Synthesis, and Regulation. EcoSal Plus 2021; 9:eESP-0010-2020. [PMID: 33470191 PMCID: PMC11168573 DOI: 10.1128/ecosalplus.esp-0010-2020] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Indexed: 02/06/2023]
Abstract
Peptidoglycan is a defining feature of the bacterial cell wall. Initially identified as a target of the revolutionary beta-lactam antibiotics, peptidoglycan has become a subject of much interest for its biology, its potential for the discovery of novel antibiotic targets, and its role in infection. Peptidoglycan is a large polymer that forms a mesh-like scaffold around the bacterial cytoplasmic membrane. Peptidoglycan synthesis is vital at several stages of the bacterial cell cycle: for expansion of the scaffold during cell elongation and for formation of a septum during cell division. It is a complex multifactorial process that includes formation of monomeric precursors in the cytoplasm, their transport to the periplasm, and polymerization to form a functional peptidoglycan sacculus. These processes require spatio-temporal regulation for successful assembly of a robust sacculus to protect the cell from turgor and determine cell shape. A century of research has uncovered the fundamentals of peptidoglycan biology, and recent studies employing advanced technologies have shed new light on the molecular interactions that govern peptidoglycan synthesis. Here, we describe the peptidoglycan structure, synthesis, and regulation in rod-shaped bacteria, particularly Escherichia coli, with a few examples from Salmonella and other diverse organisms. We focus on the pathway of peptidoglycan sacculus elongation, with special emphasis on discoveries of the past decade that have shaped our understanding of peptidoglycan biology.
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Affiliation(s)
- Shambhavi Garde
- These authors contributed equally
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India 500007
| | - Pavan Kumar Chodisetti
- These authors contributed equally
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India 500007
| | - Manjula Reddy
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India 500007
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17
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Cai Y, Chen H, Yuan R, Wang F, Chen Z, Zhou B. Metagenomic analysis of soil microbial community under PFOA and PFOS stress. ENVIRONMENTAL RESEARCH 2020; 188:109838. [PMID: 32798955 DOI: 10.1016/j.envres.2020.109838] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/29/2020] [Accepted: 06/15/2020] [Indexed: 06/11/2023]
Abstract
Perfluorinated compounds (PFCs) contamination of soil has attracted global attention in recent years but influences of PFCs on microorganisms in the soil environment have not been fully described. In this study, the effects of perfluorooctane sulphonate (PFOS) and perfluoroctanoic acid (PFOA) on bacterial communities were determined by Illumina Miseq sequencing and Illumina Hiseq Xten. The stimulation of PFCs pollutants on soil bacterial richness and community diversity were observed. Sequencing information indicated that Proteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, Firmicutes, and Gemmatimonadetes were the dominant bacterial phyla. Two genera, Bacillus and Sphingomonas, exhibited adverse responses toward PFCs pollution. Carbohydrate-active enzymes (CAZy), Kyoto Encyclopedia of Genes and Genomes (KEGG) and NCBI databases were used to elucidate the proteins and function action of soil microbial to PFCs pollution. Pathways such as Carbohydrate metabolism, Global and overview maps and Membrane transport in the soil microbes were affected by PFCs stress. CAZy analysis revealed that glycosyl transferases (GTs) in PFCs-polluted soils showed more active, while glycoside hydrolases (GHs) were inhibited severely.
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Affiliation(s)
- Yanping Cai
- Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Huilun Chen
- Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China.
| | - Rongfang Yuan
- Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Fei Wang
- Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Zhongbing Chen
- Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 16500, Prague, Czech Republic
| | - Beihai Zhou
- Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, 100083, China.
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18
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Bharadwaj VS, Knott BC, Ståhlberg J, Beckham GT, Crowley MF. The hydrolysis mechanism of a GH45 cellulase and its potential relation to lytic transglycosylase and expansin function. J Biol Chem 2020; 295:4477-4487. [PMID: 32054684 DOI: 10.1074/jbc.ra119.011406] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 02/12/2020] [Indexed: 11/06/2022] Open
Abstract
Family 45 glycoside hydrolases (GH45) are endoglucanases that are integral to cellulolytic secretomes, and their ability to break down cellulose has been successfully exploited in textile and detergent industries. In addition to their industrial relevance, understanding the molecular mechanism of GH45-catalyzed hydrolysis is of fundamental importance because of their structural similarity to cell wall-modifying enzymes such as bacterial lytic transglycosylases (LTs) and expansins present in bacteria, plants, and fungi. Our understanding of the catalytic itinerary of GH45s has been incomplete because a crystal structure with substrate spanning the -1 to +1 subsites is currently lacking. Here we constructed and validated a putative Michaelis complex in silico and used it to elucidate the hydrolytic mechanism in a GH45, Cel45A from the fungus Humicola insolens, via unbiased simulation approaches. These molecular simulations revealed that the solvent-exposed active-site architecture results in lack of coordination for the hydroxymethyl group of the substrate at the -1 subsite. This lack of coordination imparted mobility to the hydroxymethyl group and enabled a crucial hydrogen bond with the catalytic acid during and after the reaction. This suggests the possibility of a nonhydrolytic reaction mechanism when the catalytic base aspartic acid is missing, as is the case in some LTs (murein transglycosylase A) and expansins. We calculated reaction free energies and demonstrate the thermodynamic feasibility of the hydrolytic and nonhydrolytic reaction mechanisms. Our results provide molecular insights into the hydrolysis mechanism in HiCel45A, with possible implications for elucidating the elusive catalytic mechanism in LTs and expansins.
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Affiliation(s)
- Vivek S Bharadwaj
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401
| | - Brandon C Knott
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401
| | - Jerry Ståhlberg
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P. O. Box 7015, 750 07 Uppsala, Sweden
| | - Gregg T Beckham
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, Colorado 80401
| | - Michael F Crowley
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401
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19
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Williams AH, Wheeler R, Deghmane AE, Santecchia I, Schaub RE, Hicham S, Moya Nilges M, Malosse C, Chamot-Rooke J, Haouz A, Dillard JP, Robins WP, Taha MK, Gomperts Boneca I. Defective lytic transglycosylase disrupts cell morphogenesis by hindering cell wall de- O-acetylation in Neisseria meningitidis. eLife 2020; 9:e51247. [PMID: 32022687 PMCID: PMC7083599 DOI: 10.7554/elife.51247] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 02/04/2020] [Indexed: 12/17/2022] Open
Abstract
Lytic transglycosylases (LT) are enzymes involved in peptidoglycan (PG) remodeling. However, their contribution to cell-wall-modifying complexes and their potential as antimicrobial drug targets remains unclear. Here, we determined a high-resolution structure of the LT, an outer membrane lipoprotein from Neisseria species with a disordered active site helix (alpha helix 30). We show that deletion of the conserved alpha-helix 30 interferes with the integrity of the cell wall, disrupts cell division, cell separation, and impairs the fitness of the human pathogen Neisseria meningitidis during infection. Additionally, deletion of alpha-helix 30 results in hyperacetylated PG, suggesting this LtgA variant affects the function of the PG de-O-acetylase (Ape 1). Our study revealed that Ape 1 requires LtgA for optimal function, demonstrating that LTs can modulate the activity of their protein-binding partner. We show that targeting specific domains in LTs can be lethal, which opens the possibility that LTs are useful drug-targets.
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Affiliation(s)
- Allison Hillary Williams
- Unité Biologie et Génétique de la Paroi Bactérienne, Institut Pasteur; Groupe Avenir, INSERM 75015ParisFrance
| | - Richard Wheeler
- Unité Biologie et Génétique de la Paroi Bactérienne, Institut Pasteur; Groupe Avenir, INSERM 75015ParisFrance
- Tumour Immunology and Immunotherapy, Institut Gustave RoussyVillejuifFrance
| | | | - Ignacio Santecchia
- Unité Biologie et Génétique de la Paroi Bactérienne, Institut Pasteur; Groupe Avenir, INSERM 75015ParisFrance
- Universté Paris Descartes, Sorbonne Paris CitéParisFrance
| | - Ryan E Schaub
- Department of Medical Microbiology and Immunology, University of Wisconsin-MadisonMadisonUnited States
| | - Samia Hicham
- Unité Biologie et Génétique de la Paroi Bactérienne, Institut Pasteur; Groupe Avenir, INSERM 75015ParisFrance
| | - Maryse Moya Nilges
- Unité Technologie et Service BioImagerie Ultrastructural, Institut PasteurParisFrance
| | - Christian Malosse
- Unité Technologie et Service Spectrométrie de Masse pour la Biologie, Institut Pasteur; UMR 3528, CNRS 75015ParisFrance
| | - Julia Chamot-Rooke
- Unité Technologie et Service Spectrométrie de Masse pour la Biologie, Institut Pasteur; UMR 3528, CNRS 75015ParisFrance
| | - Ahmed Haouz
- Plate-forme de Cristallographie-C2RT, Institut Pasteur; UMR3528, CNRS 75015ParisFrance
| | - Joseph P Dillard
- Department of Medical Microbiology and Immunology, University of Wisconsin-MadisonMadisonUnited States
| | - William P Robins
- Department of Microbiology, Harvard Medical SchoolBostonUnited States
| | | | - Ivo Gomperts Boneca
- Unité Biologie et Génétique de la Paroi Bactérienne, Institut Pasteur; Groupe Avenir, INSERM 75015ParisFrance
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20
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Anderson EM, Sychantha D, Brewer D, Clarke AJ, Geddes-McAlister J, Khursigara CM. Peptidoglycomics reveals compositional changes in peptidoglycan between biofilm- and planktonic-derived Pseudomonas aeruginosa. J Biol Chem 2019; 295:504-516. [PMID: 31771981 DOI: 10.1074/jbc.ra119.010505] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 11/25/2019] [Indexed: 12/14/2022] Open
Abstract
Peptidoglycan (PG) is a critical component of the bacterial cell wall and is composed of a repeating β-1,4-linked disaccharide of N-acetylglucosamine and N-acetylmuramic acid appended with a highly conserved stem peptide. In Gram-negative bacteria, PG is assembled in the cytoplasm and exported into the periplasm where it undergoes considerable maturation, modification, or degradation depending on the growth phase or presence of environmental stressors. These modifications serve important functions in diverse processes, including PG turnover, cell elongation/division, and antibiotic resistance. Conventional methods for analyzing PG composition are complex and time-consuming. We present here a streamlined MS-based method that combines differential analysis with statistical 1D annotation approaches to quantitatively compare PGs produced in planktonic- and biofilm-cultured Pseudomonas aeruginosa We identified a core assembly of PG that is present in high abundance and that does not significantly differ between the two growth states. We also identified an adaptive PG assembly that is present in smaller amounts and fluctuates considerably between growth states in response to physiological changes. Biofilm-derived adaptive PG exhibited significant changes compared with planktonic-derived PG, including amino acid substitutions of the stem peptide and modifications that indicate changes in the activity of amidases, deacetylases, and lytic transglycosylases. The results of this work also provide first evidence of de-N-acetylated muropeptides from P. aeruginosa The method developed here offers a robust and reproducible workflow for accurately determining PG composition in samples that can be used to assess global PG fluctuations in response to changing growth conditions or external stimuli.
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Affiliation(s)
- Erin M Anderson
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1, Canada
| | - David Sychantha
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1, Canada
| | - Dyanne Brewer
- Mass Spectrometry Facility, University of Guelph, Ontario N1G 2W1, Canada
| | - Anthony J Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1, Canada
| | - Jennifer Geddes-McAlister
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1, Canada; Mass Spectrometry Facility, University of Guelph, Ontario N1G 2W1, Canada.
| | - Cezar M Khursigara
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1, Canada; Mass Spectrometry Facility, University of Guelph, Ontario N1G 2W1, Canada.
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21
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Origin of a Core Bacterial Gene via Co-option and Detoxification of a Phage Lysin. Curr Biol 2019; 29:1634-1646.e6. [PMID: 31080080 DOI: 10.1016/j.cub.2019.04.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 02/12/2019] [Accepted: 04/10/2019] [Indexed: 11/23/2022]
Abstract
Temperate phages constitute a potentially beneficial genetic reservoir for bacterial innovation despite being selfish entities encoding an infection cycle inherently at odds with bacterial fitness. These phages integrate their genomes into the bacterial host during infection, donating new but deleterious genetic material: the phage genome encodes toxic genes, such as lysins, that kill the bacterium during the phage infection cycle. Remarkably, some bacteria have exploited the destructive properties of phage genes for their own benefit by co-opting them as toxins for functions related to bacterial warfare, virulence, and secretion. However, do toxic phage genes ever become raw material for functional innovation? Here, we report on a toxic phage gene whose product has lost its toxicity and has become a domain of a core cellular factor, SpmX, throughout the bacterial order Caulobacterales. Using a combination of phylogenetics, bioinformatics, structural biology, cell biology, and biochemistry, we have investigated the origin and function of SpmX and determined that its occurrence is the result of the detoxification of a phage peptidoglycan hydrolase gene. We show that the retained, attenuated activity of the phage-derived domain plays an important role in proper cell morphology and developmental regulation in representatives of this large bacterial clade. To our knowledge, this is the first observation of a phage gene domestication event in which a toxic phage gene has been co-opted for core cellular function at the root of a large bacterial clade.
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22
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Vermassen A, Leroy S, Talon R, Provot C, Popowska M, Desvaux M. Cell Wall Hydrolases in Bacteria: Insight on the Diversity of Cell Wall Amidases, Glycosidases and Peptidases Toward Peptidoglycan. Front Microbiol 2019; 10:331. [PMID: 30873139 PMCID: PMC6403190 DOI: 10.3389/fmicb.2019.00331] [Citation(s) in RCA: 179] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 02/08/2019] [Indexed: 11/13/2022] Open
Abstract
The cell wall (CW) of bacteria is an intricate arrangement of macromolecules, at least constituted of peptidoglycan (PG) but also of (lipo)teichoic acids, various polysaccharides, polyglutamate and/or proteins. During bacterial growth and division, there is a constant balance between CW degradation and biosynthesis. The CW is remodeled by bacterial hydrolases, whose activities are carefully regulated to maintain cell integrity or lead to bacterial death. Each cell wall hydrolase (CWH) has a specific role regarding the PG: (i) cell wall amidase (CWA) cleaves the amide bond between N-acetylmuramic acid and L-alanine residue at the N-terminal of the stem peptide, (ii) cell wall glycosidase (CWG) catalyses the hydrolysis of the glycosidic linkages, whereas (iii) cell wall peptidase (CWP) cleaves amide bonds between amino acids within the PG chain. After an exhaustive overview of all known conserved catalytic domains responsible for CWA, CWG, and CWP activities, this review stresses that the CWHs frequently display a modular architecture combining multiple and/or different catalytic domains, including some lytic transglycosylases as well as CW binding domains. From there, direct physiological and collateral roles of CWHs in bacterial cells are further discussed.
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Affiliation(s)
- Aurore Vermassen
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
| | - Sabine Leroy
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
| | - Régine Talon
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
| | | | - Magdalena Popowska
- Department of Applied Microbiology, Faculty of Biology, Institute of Microbiology, University of Warsaw, Warsaw, Poland
| | - Mickaël Desvaux
- Université Clermont Auvergne, INRA, MEDiS, Clermont-Ferrand, France
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23
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Biochemical and Phylogenetic Study of SltF, a Flagellar Lytic Transglycosylase from Rhodobacter sphaeroides. J Bacteriol 2018; 200:JB.00397-18. [PMID: 30061356 DOI: 10.1128/jb.00397-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 07/27/2018] [Indexed: 11/20/2022] Open
Abstract
In this work, we have characterized the soluble lytic transglycosylase (SltF) from Rhodobacter sphaeroides that interacts with the scaffolding protein FlgJ in the periplasm to open space at the cell wall peptidoglycan heteropolymer for the emerging rod. The characterization of the genetic context of flgJ and sltF in alphaproteobacteria shows that these two separate genes coexist frequently in a flagellar gene cluster. Two domains of unknown function in SltF were studied, and the results show that the deletion of a 17-amino-acid segment near the N terminus does not show a recognizable phenotype, whereas the deletion of 47 and 95 amino acids of the C terminus of SltF disrupts the interaction with FlgJ without affecting the transglycosylase catalytic activity of SltF. These mutant proteins are unable to support swimming, indicating that the physical interaction between SltF and FlgJ is central for flagellar formation. In a maximum likelihood tree of representative lytic transglycosylases, all of the flagellar SltF proteins cluster in subfamily 1F. From this analysis, it was also revealed that the lytic transglycosylases related to the type III secretion systems present in pathogens cluster with the closely related flagellar transglycosylases.IMPORTANCE Flagellar biogenesis is a highly orchestrated event where the flagellar structure spans the bacterial cell envelope. The rod diameter of approximately 4 nm is larger than the estimated pore size of the peptidoglycan layer; hence, its insertion requires the localized and controlled lysis of the cell wall. We found that a 47-residue domain of the C terminus of the lytic transglycosylase (LT) SltF of R. sphaeroides is involved in the recognition of the rod chaperone FlgJ. We also found that in many alphaproteobacteria, the flagellar cluster includes a homolog of SltF and FlgJ, indicating that association of an LT with the flagellar machinery is ancestral. A maximum likelihood tree shows that family 1 of LTs segregates into seven subfamilies.
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24
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Yang S, Gao X, Meng J, Zhang A, Zhou Y, Long M, Li B, Deng W, Jin L, Zhao S, Wu D, He Y, Li C, Liu S, Huang Y, Zhang H, Zou L. Metagenomic Analysis of Bacteria, Fungi, Bacteriophages, and Helminths in the Gut of Giant Pandas. Front Microbiol 2018; 9:1717. [PMID: 30108570 PMCID: PMC6080571 DOI: 10.3389/fmicb.2018.01717] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 07/10/2018] [Indexed: 11/13/2022] Open
Abstract
To obtain full details of gut microbiota, including bacteria, fungi, bacteriophages, and helminths, in giant pandas (GPs), we created a comprehensive microbial genome database and used metagenomic sequences to align against the database. We delineated a detailed and different gut microbiota structures of GPs. A total of 680 species of bacteria, 198 fungi, 185 bacteriophages, and 45 helminths were found. Compared with 16S rRNA sequencing, the dominant bacterium phyla not only included Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria but also Cyanobacteria and other eight phyla. Aside from Ascomycota, Basidiomycota, and Glomeromycota, Mucoromycota, and Microsporidia were the dominant fungi phyla. The bacteriophages were predominantly dsDNA Myoviridae, Siphoviridae, Podoviridae, ssDNA Inoviridae, and Microviridae. For helminths, phylum Nematoda was the dominant. In addition to previously described parasites, another 44 species of helminths were found in GPs. Also, differences in abundance of microbiota were found between the captive, semiwild, and wild GPs. A total of 1,739 genes encoding cellulase, β-glucosidase, and cellulose β-1,4-cellobiosidase were responsible for the metabolism of cellulose, and 128,707 putative glycoside hydrolase genes were found in bacteria/fungi. Taken together, the results indicated not only bacteria but also fungi, bacteriophages, and helminths were diverse in gut of giant pandas, which provided basis for the further identification of role of gut microbiota. Besides, metagenomics revealed that the bacteria/fungi in gut of GPs harbor the ability of cellulose and hemicellulose degradation.
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Affiliation(s)
- Shengzhi Yang
- Department of Applied Microbiology, College of Resources, Sichuan Agricultural University, Chengdu, China
| | - Xin Gao
- Department of Nutrition and Food Science, University of Maryland, College Park, College Park, MD, United States
| | - Jianghong Meng
- Department of Nutrition and Food Science, University of Maryland, College Park, College Park, MD, United States
| | - Anyun Zhang
- College of Life Sciences, Sichuan University, Chengdu, China
| | - Yingmin Zhou
- The China Conservation and Research Center for the Giant Panda, Wolong, China
| | - Mei Long
- Department of Applied Microbiology, College of Resources, Sichuan Agricultural University, Chengdu, China
| | - Bei Li
- Department of Applied Microbiology, College of Resources, Sichuan Agricultural University, Chengdu, China
| | - Wenwen Deng
- Department of Applied Microbiology, College of Resources, Sichuan Agricultural University, Chengdu, China
| | - Lei Jin
- Department of Applied Microbiology, College of Resources, Sichuan Agricultural University, Chengdu, China
| | - Siyue Zhao
- Department of Applied Microbiology, College of Resources, Sichuan Agricultural University, Chengdu, China
| | - Daifu Wu
- The China Conservation and Research Center for the Giant Panda, Wolong, China
| | - Yongguo He
- The China Conservation and Research Center for the Giant Panda, Wolong, China
| | - Caiwu Li
- The China Conservation and Research Center for the Giant Panda, Wolong, China
| | - Shuliang Liu
- College of Food Science, Sichuan Agricultural University, Ya’an, China
| | - Yan Huang
- The China Conservation and Research Center for the Giant Panda, Wolong, China
- Key Laboratory of State Forestry and Grassland Administration on Conservation Biology of Rare Animals in The Giant Panda National Park (China Conservation and Research Center of Giant Panda), Wolong, China
| | - Hemin Zhang
- The China Conservation and Research Center for the Giant Panda, Wolong, China
- Key Laboratory of State Forestry and Grassland Administration on Conservation Biology of Rare Animals in The Giant Panda National Park (China Conservation and Research Center of Giant Panda), Wolong, China
| | - Likou Zou
- Department of Applied Microbiology, College of Resources, Sichuan Agricultural University, Chengdu, China
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25
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Dik DA, Fisher JF, Mobashery S. Cell-Wall Recycling of the Gram-Negative Bacteria and the Nexus to Antibiotic Resistance. Chem Rev 2018; 118:5952-5984. [PMID: 29847102 PMCID: PMC6855303 DOI: 10.1021/acs.chemrev.8b00277] [Citation(s) in RCA: 130] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The importance of the cell wall to the viability of the bacterium is underscored by the breadth of antibiotic structures that act by blocking key enzymes that are tasked with cell-wall creation, preservation, and regulation. The interplay between cell-wall integrity, and the summoning forth of resistance mechanisms to deactivate cell-wall-targeting antibiotics, involves exquisite orchestration among cell-wall synthesis and remodeling and the detection of and response to the antibiotics through modulation of gene regulation by specific effectors. Given the profound importance of antibiotics to the practice of medicine, the assertion that understanding this interplay is among the most fundamentally important questions in bacterial physiology is credible. The enigmatic regulation of the expression of the AmpC β-lactamase, a clinically significant and highly regulated resistance response of certain Gram-negative bacteria to the β-lactam antibiotics, is the exemplar of this challenge. This review gives a current perspective to this compelling, and still not fully solved, 35-year enigma.
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Affiliation(s)
- David A. Dik
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Jed F. Fisher
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame, Indiana 46556, United States
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26
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Vijayaraghavan J, Kumar V, Krishnan NP, Kaufhold RT, Zeng X, Lin J, van den Akker F. Structural studies and molecular dynamics simulations suggest a processive mechanism of exolytic lytic transglycosylase from Campylobacter jejuni. PLoS One 2018; 13:e0197136. [PMID: 29758058 PMCID: PMC5951611 DOI: 10.1371/journal.pone.0197136] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 04/26/2018] [Indexed: 11/21/2022] Open
Abstract
The bacterial soluble lytic transglycosylase (LT) breaks down the peptidoglycan (PG) layer during processes such as cell division. We present here crystal structures of the soluble LT Cj0843 from Campylobacter jejuni with and without bulgecin A inhibitor in the active site. Cj0843 has a doughnut shape similar but not identical to that of E. coli SLT70. The C-terminal catalytic domain is preceded by an L-domain, a large helical U-domain, a flexible linker, and a small N-terminal NU-domain. The flexible linker allows the NU-domain to reach over and complete the circular shape, using residues conserved in the Epsilonproteobacteria LT family. The inner surface of the Cj0843 doughnut is mostly positively charged including a pocket that has 8 Arg/Lys residues. Molecular dynamics simulations with PG strands revealed a potential functional role for this pocket in anchoring the negatively charged terminal tetrapeptide of the PG during several steps in the reaction including homing and aligning the PG strand for exolytic cleavage, and subsequent ratcheting of the PG strand to enhance processivity in degrading PG strands.
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Affiliation(s)
- Jagamya Vijayaraghavan
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH, United States of America
| | - Vijay Kumar
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH, United States of America
| | - Nikhil P. Krishnan
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH, United States of America
| | - Ross T. Kaufhold
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH, United States of America
| | - Ximin Zeng
- Institute of agriculture, University of Tennessee, Knoxville, TN, United States of America
| | - Jun Lin
- Institute of agriculture, University of Tennessee, Knoxville, TN, United States of America
| | - Focco van den Akker
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH, United States of America
- * E-mail:
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27
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Williams AH, Wheeler R, Rateau L, Malosse C, Chamot-Rooke J, Haouz A, Taha MK, Boneca IG. A step-by-step in crystallo guide to bond cleavage and 1,6-anhydro-sugar product synthesis by a peptidoglycan-degrading lytic transglycosylase. J Biol Chem 2018; 293:6000-6010. [PMID: 29483188 DOI: 10.1074/jbc.ra117.001095] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 02/12/2018] [Indexed: 01/13/2023] Open
Abstract
Lytic transglycosylases (LTs) are a class of enzymes important for the recycling and metabolism of peptidoglycan (PG). LTs cleave the β-1,4-glycosidic bond between N-acetylmuramic acid (MurNAc) and GlcNAc in the PG glycan strand, resulting in the concomitant formation of 1,6-anhydro-N-acetylmuramic acid and GlcNAc. No LTs reported to date have utilized chitins as substrates, despite the fact that chitins are GlcNAc polymers linked via β-1,4-glycosidic bonds, which are the known site of chemical activity for LTs. Here, we demonstrate enzymatically that LtgA, a non-canonical, substrate-permissive LT from Neisseria meningitidis utilizes chitopentaose ((GlcNAc)5) as a substrate to produce three newly identified sugars: 1,6-anhydro-chitobiose, 1,6-anhydro-chitotriose, and 1,6-anhydro-chitotetraose. Although LTs have been widely studied, their complex reactions have not previously been visualized in the crystalline state because macromolecular PG is insoluble. Here, we visualized the cleavage of the glycosidic bond and the liberation of GlcNAc-derived residues by LtgA, followed by the synthesis of atypical 1,6-anhydro-GlcNAc derivatives. In addition to the newly identified anhydro-chitin products, we identified trapped intermediates, unpredicted substrate rearrangements, sugar distortions, and a conserved crystallographic water molecule bound to the catalytic glutamate of a high-resolution native LT. This study enabled us to propose a revised alternative mechanism for LtgA that could also be applicable to other LTs. Our work contributes to the understanding of the mechanisms of LTs in bacterial cell wall biology.
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Affiliation(s)
- Allison H Williams
- From the Institut Pasteur, Département de Microbiologie, Unité Biologie et Génétique de la Paroi Bactérienne, 75015 Paris, France, .,INSERM, 75015 Paris, France
| | - Richard Wheeler
- From the Institut Pasteur, Département de Microbiologie, Unité Biologie et Génétique de la Paroi Bactérienne, 75015 Paris, France.,INSERM, 75015 Paris, France.,the Gustave Roussy Comprehensive Cancer Center, Tumour Immunology and Immunotherapy, F-94805 Villejuif, France
| | - Lesly Rateau
- From the Institut Pasteur, Département de Microbiologie, Unité Biologie et Génétique de la Paroi Bactérienne, 75015 Paris, France.,INSERM, 75015 Paris, France
| | - Christian Malosse
- the Institut Pasteur, CNRS USR 2000, Unité des Spectrométrie de Masse Structurale et Proteomique, 75015 Paris, France
| | - Julia Chamot-Rooke
- the Institut Pasteur, CNRS USR 2000, Unité des Spectrométrie de Masse Structurale et Proteomique, 75015 Paris, France
| | - Ahmed Haouz
- the Institut Pasteur, Plate-forme de Cristallographie, CNRS-UMR3528, 75724 Paris, France, and
| | - Muhamed-Kheir Taha
- the Institut Pasteur, Département d'Infection et Epidémiologie, Unité des Infection Bactériennes Invasives, 75015 Paris, France
| | - Ivo Gomperts Boneca
- From the Institut Pasteur, Département de Microbiologie, Unité Biologie et Génétique de la Paroi Bactérienne, 75015 Paris, France, .,INSERM, 75015 Paris, France
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28
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Yin J, Sun Y, Sun Y, Yu Z, Qiu J, Gao H. Deletion of Lytic Transglycosylases Increases Beta-Lactam Resistance in Shewanella oneidensis. Front Microbiol 2018; 9:13. [PMID: 29403465 PMCID: PMC5786531 DOI: 10.3389/fmicb.2018.00013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 01/05/2018] [Indexed: 01/07/2023] Open
Abstract
Production of chromosome-encoded β-lactamases confers resistance to β-lactams in many Gram-negative bacteria. Some inducible β-lactamases, especially the class C β-lactamase AmpC in Enterobacteriaceae, share a common regulatory mechanism, the ampR-ampC paradigm. Induction of ampC is intimately linked to peptidoglycan recycling, and the LysR-type transcriptional regulator AmpR plays a central role in the process. However, our previous studies have demonstrated that the expression of class D β-lactamase gene blaA in Shewanella oneidensis is distinct from the established paradigm since an AmpR homolog is absent and major peptidoglycan recycling enzymes play opposite roles in β-lactamase expression. Given that lytic transglycosylases (LTs), a class of peptidoglycan hydrolases cleaving the β-1,4 glycosidic linkage in glycan strands of peptidoglycan, can disturb peptidoglycan recycling, and thus may affect induction of blaA. In this study, we investigated impacts of such enzymes on susceptibility to β-lactams. Deletion of three LTs (SltY, MltB and MltB2) increased β-lactam resistance, while four other LTs (MltD, MltD2, MltF, and Slt2) seemed dispensable to β-lactam resistance. The double LT mutants ΔmltBΔmltB2 and ΔsltYΔmltB2 had β-lactam resistance stronger than any of the single mutants. Deletion of ampG (encoding permease AmpG) and mrcA (encoding penicillin binding protein 1a, PBP1a) from both double LT mutants further increased the resistance to β-lactams. Notably, all increased β-lactam resistance phenotypes were in accordance with enhanced blaA expression. Although significant, the increase in β-lactamase activity after inactivating LTs is much lower than that produced by PBP1a inactivation. Our data implicate that LTs play important roles in blaA expression in S. oneidensis.
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Affiliation(s)
- Jianhua Yin
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China.,Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, China.,College of Life Sciences, Nanchang University, Nanchang, China
| | - Yiyang Sun
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Yijuan Sun
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Zhiliang Yu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Juanping Qiu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Haichun Gao
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, China
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29
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Abstract
Bacterial endospores possess multiple integument layers, one of which is the cortex peptidoglycan wall. The cortex is essential for the maintenance of spore core dehydration and dormancy and contains structural modifications that differentiate it from vegetative cell peptidoglycan and determine its fate during spore germination. Following the engulfment stage of sporulation, the cortex is synthesized within the intermembrane space surrounding the forespore. Proteins responsible for cortex synthesis are produced in both the forespore and mother cell compartments. While some of these proteins also contribute to vegetative cell wall synthesis, others are sporulation specific. In order for the bacterial endospore to germinate and resume metabolism, the cortex peptidoglycan must first be degraded through the action of germination-specific lytic enzymes. These enzymes are present, yet inactive, in the dormant spore and recognize the muramic-δ-lactam modification present in the cortex. Germination-specific lytic enzymes across Bacillaceae and Clostridiaceae share this specificity determinant, which ensures that the spore cortex is hydrolyzed while the vegetative cell wall remains unharmed. Bacillus species tend to possess two redundant enzymes, SleB and CwlJ, capable of sufficient cortex degradation, while the clostridia have only one, SleC. Additional enzymes are often present that cannot initiate the cortex degradation process, but which can increase the rate of release of small fragments into the medium. Between the two families, the enzymes also differ in the enzymatic activities they possess and the mechanisms acting to restrict their activation until germination has been initiated.
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30
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Dhar S, Kumari H, Balasubramanian D, Mathee K. Cell-wall recycling and synthesis in Escherichia coli and Pseudomonas aeruginosa – their role in the development of resistance. J Med Microbiol 2018; 67:1-21. [DOI: 10.1099/jmm.0.000636] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- Supurna Dhar
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Hansi Kumari
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | | | - Kalai Mathee
- Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
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31
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Noronha MF, Lacerda Júnior GV, Gilbert JA, de Oliveira VM. Taxonomic and functional patterns across soil microbial communities of global biomes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 609:1064-1074. [PMID: 28787780 DOI: 10.1016/j.scitotenv.2017.07.159] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 07/17/2017] [Accepted: 07/18/2017] [Indexed: 05/24/2023]
Affiliation(s)
- Melline Fontes Noronha
- Microbial Resources Division, Multidisciplinary Center for Chemistry, Biology and Agriculture Research (CPQBA), Campinas University, Brazil; Institute of Biology, Campinas University, Brazil.
| | - Gileno Vieira Lacerda Júnior
- Microbial Resources Division, Multidisciplinary Center for Chemistry, Biology and Agriculture Research (CPQBA), Campinas University, Brazil; Institute of Biology, Campinas University, Brazil
| | - Jack A Gilbert
- The Microbiome Center, Department of Surgery, University of Chicago, Chicago, IL, USA; The Microbiome Center, Bioscience Division, Argonne National Laboratory, Lemont, IL, USA
| | - Valéria Maia de Oliveira
- Microbial Resources Division, Multidisciplinary Center for Chemistry, Biology and Agriculture Research (CPQBA), Campinas University, Brazil
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32
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Dik DA, Marous DR, Fisher JF, Mobashery S. Lytic transglycosylases: concinnity in concision of the bacterial cell wall. Crit Rev Biochem Mol Biol 2017. [PMID: 28644060 DOI: 10.1080/10409238.2017.1337705] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The lytic transglycosylases (LTs) are bacterial enzymes that catalyze the non-hydrolytic cleavage of the peptidoglycan structures of the bacterial cell wall. They are not catalysts of glycan synthesis as might be surmised from their name. Notwithstanding the seemingly mundane reaction catalyzed by the LTs, their lytic reactions serve bacteria for a series of astonishingly diverse purposes. These purposes include cell-wall synthesis, remodeling, and degradation; for the detection of cell-wall-acting antibiotics; for the expression of the mechanism of cell-wall-acting antibiotics; for the insertion of secretion systems and flagellar assemblies into the cell wall; as a virulence mechanism during infection by certain Gram-negative bacteria; and in the sporulation and germination of Gram-positive spores. Significant advances in the mechanistic understanding of each of these processes have coincided with the successive discovery of new LTs structures. In this review, we provide a systematic perspective on what is known on the structure-function correlations for the LTs, while simultaneously identifying numerous opportunities for the future study of these enigmatic enzymes.
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Affiliation(s)
- David A Dik
- a Department of Chemistry and Biochemistry , University of Notre Dame , Notre Dame , IN , USA
| | - Daniel R Marous
- a Department of Chemistry and Biochemistry , University of Notre Dame , Notre Dame , IN , USA
| | - Jed F Fisher
- a Department of Chemistry and Biochemistry , University of Notre Dame , Notre Dame , IN , USA
| | - Shahriar Mobashery
- a Department of Chemistry and Biochemistry , University of Notre Dame , Notre Dame , IN , USA
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33
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Dai J. New insights into a hot environment for early life. ENVIRONMENTAL MICROBIOLOGY REPORTS 2017; 9:203-210. [PMID: 28276199 DOI: 10.1111/1758-2229.12528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Investigating the physical-chemical setting of early life is a challenging task. In this contribution, the author attempted to introduce a provocative concept from cosmology - cosmic microwave background (CMB), which is the residual thermal radiation from a hot early Universe - to the field. For this purpose, the author revisited a recently deduced biomarker, the 1,6-anhydro bond of sugars in bacteria. In vitro, the 1,6-anhydro bond of sugars reflects and captures residual thermal radiation in thermochemical processes and therefore is somewhat analogous to CMB. In vivo, the formation process of the 1,6-anhydro bond of sugars on the peptidoglycan of prokaryotic cell wall is parallel to in vitro processes, suggesting that the 1,6-anhydro bond is an ideal CMB-like analogue that suggests a hot setting for early life. The CMB-like 1,6-anhydro bond is involved in the life cycle of viruses and the metabolism of eukaryotes, underlying this notion. From a novel perspective, the application of the concept of the CMB to microbial ecology may give new insights into a hot environment, such as hydrothermal vents, supporting early life and providing hypotheses to test in molecular palaeontology.
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Affiliation(s)
- Jianghong Dai
- School of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, No. 68 Xuefu Road (S), Evergreen Garden, Wuhan, 430023, People's Republic of China
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34
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Lee M, Hesek D, Dik DA, Fishovitz J, Lastochkin E, Boggess B, Fisher JF, Mobashery S. From Genome to Proteome to Elucidation of Reactions for All Eleven Known Lytic Transglycosylases from Pseudomonas aeruginosa. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201611279] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Mijoon Lee
- Department of Chemistry and Biochemistry; University of Notre Dame; Notre Dame IN 46556 USA
| | - Dusan Hesek
- Department of Chemistry and Biochemistry; University of Notre Dame; Notre Dame IN 46556 USA
| | - David A. Dik
- Department of Chemistry and Biochemistry; University of Notre Dame; Notre Dame IN 46556 USA
| | - Jennifer Fishovitz
- Department of Chemistry and Biochemistry; University of Notre Dame; Notre Dame IN 46556 USA
| | - Elena Lastochkin
- Department of Chemistry and Biochemistry; University of Notre Dame; Notre Dame IN 46556 USA
| | - Bill Boggess
- Department of Chemistry and Biochemistry; University of Notre Dame; Notre Dame IN 46556 USA
| | - Jed F. Fisher
- Department of Chemistry and Biochemistry; University of Notre Dame; Notre Dame IN 46556 USA
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry; University of Notre Dame; Notre Dame IN 46556 USA
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Lee M, Hesek D, Dik DA, Fishovitz J, Lastochkin E, Boggess B, Fisher JF, Mobashery S. From Genome to Proteome to Elucidation of Reactions for All Eleven Known Lytic Transglycosylases from Pseudomonas aeruginosa. Angew Chem Int Ed Engl 2017; 56:2735-2739. [PMID: 28128504 DOI: 10.1002/anie.201611279] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 12/09/2016] [Indexed: 11/07/2022]
Abstract
An enzyme superfamily, the lytic transglycosylases (LTs), occupies the space between the two membranes of Gram-negative bacteria. LTs catalyze the non-hydrolytic cleavage of the bacterial peptidoglycan cell-wall polymer. This reaction is central to the growth of the cell wall, for excavating the cell wall for protein insertion, and for monitoring the cell wall so as to initiate resistance responses to cell-wall-acting antibiotics. The nefarious Gram-negative pathogen Pseudomonas aeruginosa encodes eleven LTs. With few exceptions, their substrates and functions are unknown. Each P. aeruginosa LT was expressed as a soluble protein and evaluated with a panel of substrates (both simple and complex mimetics of their natural substrates). Thirty-one distinct products distinguish these LTs with respect to substrate recognition, catalytic activity, and relative exolytic or endolytic ability. These properties are foundational to an understanding of the LTs as catalysts and as antibiotic targets.
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Affiliation(s)
- Mijoon Lee
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Dusan Hesek
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - David A Dik
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Jennifer Fishovitz
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Elena Lastochkin
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Bill Boggess
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Jed F Fisher
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
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Mehta KK, Paskaleva EE, Wu X, Grover N, Mundra RV, Chen K, Zhang Y, Yang Z, Feng H, Dordick JS, Kane RS. Newly identified bacteriolytic enzymes that target a wide range of clinical isolates of Clostridium difficile. Biotechnol Bioeng 2016; 113:2568-2576. [PMID: 27260850 PMCID: PMC5367918 DOI: 10.1002/bit.26029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 05/23/2016] [Accepted: 05/29/2016] [Indexed: 12/18/2022]
Abstract
Clostridium difficile has emerged as a major cause of infectious diarrhea in hospitalized patients, with increasing mortality rate and annual healthcare costs exceeding $3 billion. Since C. difficile infections are associated with the use of antibiotics, there is an urgent need to develop treatments that can inactivate the bacterium selectively without affecting commensal microflora. Lytic enzymes from bacteria and bacteriophages show promise as highly selective and effective antimicrobial agents. These enzymes often have a modular structure, consisting of a catalytic domain and a binding domain. In the current work, using consensus catalytic domain and cell-wall binding domain sequences as probes, we analyzed in silico the genome of C. difficile, as well as phages infecting C. difficile. We identified two genes encoding cell lytic enzymes with possible activity against C. difficile. We cloned the genes in a suitable expression vector, expressed and purified the protein products, and tested enzyme activity in vitro. These newly identified enzymes were found to be active against C. difficile cells in a dose-dependent manner. We achieved a more than 4-log reduction in the number of viable bacteria within 5 h of application. Moreover, we found that the enzymes were active against a wide range of C. difficile clinical isolates. We also characterized the biocatalytic mechanism by identifying the specific bonds cleaved by these enzymes within the cell wall peptidoglycan. These results suggest a new approach to combating the growing healthcare problem associated with C. difficile infections. Biotechnol. Bioeng. 2016;113: 2568-2576. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Krunal K Mehta
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, 12180, New York
| | - Elena E Paskaleva
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, 12180, New York
| | - Xia Wu
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, 12180, New York
| | - Navdeep Grover
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, 12180, New York
| | - Ruchir V Mundra
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, 12180, New York
| | - Kevin Chen
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, Maryland
| | - Yongrong Zhang
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, Maryland
| | - Zhiyong Yang
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, Maryland
| | - Hanping Feng
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, Maryland
| | - Jonathan S Dordick
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York.
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, 12180, New York.
| | - Ravi S Kane
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 950 Atlantic Drive, Atlanta, 30332, Georgia.
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Schaub RE, Chan YA, Lee M, Hesek D, Mobashery S, Dillard JP. Lytic transglycosylases LtgA and LtgD perform distinct roles in remodeling, recycling and releasing peptidoglycan in Neisseria gonorrhoeae. Mol Microbiol 2016; 102:865-881. [PMID: 27608412 DOI: 10.1111/mmi.13496] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/02/2016] [Indexed: 12/17/2022]
Abstract
Neisseria gonorrhoeae releases peptidoglycan (PG) fragments during infection that provoke a large inflammatory response and, in pelvic inflammatory disease, this response leads to the death and sloughing of ciliated cells of the Fallopian tube. We characterized the biochemical functions and localization of two enzymes responsible for the release of proinflammatory PG fragments. The putative lytic transglycosylases LtgA and LtgD were shown to create the 1,6-anhydromuramyl moieties, and both enzymes were able to digest a small, synthetic tetrasaccharide dipeptide PG fragment into the cognate 1,6-anhydromuramyl-containing reaction products. Degradation of tetrasaccharide PG fragments by LtgA is the first demonstration of a family 1 lytic transglycosylase exhibiting this activity. Pulse-chase experiments in gonococci demonstrated that LtgA produces a larger amount of PG fragments than LtgD, and a vast majority of these fragments are recycled. In contrast, LtgD was necessary for wild-type levels of PG precursor incorporation and produced fragments predominantly released from the cell. Additionally, super-resolution microscopy established that LtgA localizes to the septum, whereas LtgD is localized around the cell. This investigation suggests a model where LtgD produces PG monomers in such a way that these fragments are released, whereas LtgA creates fragments that are mostly taken into the cytoplasm for recycling.
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Affiliation(s)
- Ryan E Schaub
- Department of Medical Microbiology & Immunology, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Yolande A Chan
- Department of Medical Microbiology & Immunology, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Mijoon Lee
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Dusan Hesek
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Shahriar Mobashery
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Joseph P Dillard
- Department of Medical Microbiology & Immunology, University of Wisconsin-Madison, Madison, WI, 53706, USA
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Domínguez-Gil T, Molina R, Alcorlo M, Hermoso JA. Renew or die: The molecular mechanisms of peptidoglycan recycling and antibiotic resistance in Gram-negative pathogens. Drug Resist Updat 2016; 28:91-104. [PMID: 27620957 DOI: 10.1016/j.drup.2016.07.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Antimicrobial resistance is one of the most serious health threats. Cell-wall remodeling processes are tightly regulated to warrant bacterial survival and in some cases are directly linked to antibiotic resistance. Remodeling produces cell-wall fragments that are recycled but can also act as messengers for bacterial communication, as effector molecules in immune response and as signaling molecules triggering antibiotic resistance. This review is intended to provide state-of-the-art information about the molecular mechanisms governing this process and gather structural information of the different macromolecular machineries involved in peptidoglycan recycling in Gram-negative bacteria. The growing body of literature on the 3D structures of the corresponding macromolecules reveals an extraordinary complexity. Considering the increasing incidence and widespread emergence of Gram-negative multidrug-resistant pathogens in clinics, structural information on the main actors of the recycling process paves the way for designing novel antibiotics disrupting cellular communication in the recycling-resistance pathway.
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Affiliation(s)
- Teresa Domínguez-Gil
- Department of Crystallography and Structural Biology, Inst. Química-Física "Rocasolano", CSIC, Serrano 119, 28006 Madrid, Spain
| | - Rafael Molina
- Department of Crystallography and Structural Biology, Inst. Química-Física "Rocasolano", CSIC, Serrano 119, 28006 Madrid, Spain
| | - Martín Alcorlo
- Department of Crystallography and Structural Biology, Inst. Química-Física "Rocasolano", CSIC, Serrano 119, 28006 Madrid, Spain
| | - Juan A Hermoso
- Department of Crystallography and Structural Biology, Inst. Química-Física "Rocasolano", CSIC, Serrano 119, 28006 Madrid, Spain.
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Nocadello S, Minasov G, Shuvalova LS, Dubrovska I, Sabini E, Anderson WF. Crystal Structures of the SpoIID Lytic Transglycosylases Essential for Bacterial Sporulation. J Biol Chem 2016; 291:14915-26. [PMID: 27226615 PMCID: PMC4946911 DOI: 10.1074/jbc.m116.729749] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 05/11/2016] [Indexed: 01/07/2023] Open
Abstract
Bacterial spores are the most resistant form of life known on Earth and represent a serious problem for (i) bioterrorism attack, (ii) horizontal transmission of microbial pathogens in the community, and (iii) persistence in patients and in a nosocomial environment. Stage II sporulation protein D (SpoIID) is a lytic transglycosylase (LT) essential for sporulation. The LT superfamily is a potential drug target because it is active in essential bacterial processes involving the peptidoglycan, which is unique to bacteria. However, the absence of structural information for the sporulation-specific LT enzymes has hindered mechanistic understanding of SpoIID. Here, we report the first crystal structures with and without ligands of the SpoIID family from two community relevant spore-forming pathogens, Bacillus anthracis and Clostridium difficile. The structures allow us to visualize the overall architecture, characterize the substrate recognition model, identify critical residues, and provide the structural basis for catalysis by this new family of enzymes.
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Affiliation(s)
- Salvatore Nocadello
- From the Center for Structural Genomics of Infectious Diseases, Department of Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
| | - George Minasov
- From the Center for Structural Genomics of Infectious Diseases, Department of Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
| | - Ludmilla S Shuvalova
- From the Center for Structural Genomics of Infectious Diseases, Department of Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
| | - Ievgeniia Dubrovska
- From the Center for Structural Genomics of Infectious Diseases, Department of Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
| | - Elisabetta Sabini
- From the Center for Structural Genomics of Infectious Diseases, Department of Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
| | - Wayne F Anderson
- From the Center for Structural Genomics of Infectious Diseases, Department of Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
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Modulation of the Lytic Activity of the Dedicated Autolysin for Flagellum Formation SltF by Flagellar Rod Proteins FlgB and FlgF. J Bacteriol 2016; 198:1847-56. [PMID: 27114466 DOI: 10.1128/jb.00203-16] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 04/21/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED SltF was identified previously as an autolysin required for the assembly of flagella in the alphaproteobacteria, but the nature of its peptidoglycan lytic activity remained unknown. Sequence alignment analyses suggest that it could function as either a muramidase, lytic transglycosylase, or β-N-acetylglucosaminidase. Recombinant SltF from Rhodobacter sphaeroides was purified to apparent homogeneity, and it was demonstrated to function as a lytic transglycosylase based on enzymatic assays involving mass spectrometric analyses. Circular dichroism (CD) analysis determined that it is composed of 83.4% α-structure and 1.48% β-structure and thus is similar to family 1A lytic transglycosylases. However, alignment of apparent SltF homologs identified in the genome database defined a new subfamily of the family 1 lytic transglycosylases. SltF was demonstrated to be endo-acting, cleaving within chains of peptidoglycan, with optimal activity at pH 7.0. Its activity is modulated by two flagellar rod proteins, FlgB and FlgF: FlgB both stabilizes and stimulates SltF activity, while FlgF inhibits it. Invariant Glu57 was confirmed as the sole catalytic acid/base residue of SltF. IMPORTANCE The bacterial flagellum is comprised of a basal body, hook, and helical filament, which are connected by a rod structure. With a diameter of approximately 4 nm, the rod is larger than the estimated pore size within the peptidoglycan sacculus, and hence its insertion requires the localized and controlled lysis of this essential cell wall component. In many beta- and gammaproteobacteria, this lysis is catalyzed by the β-N-acetylglucosaminidase domain of FlgJ. However, FlgJ of the alphaproteobacteria lacks this activity and instead it recruits a separate enzyme, SltF, for this purpose. In this study, we demonstrate that SltF functions as a newly identified class of lytic transglycosylases and that its autolytic activity is uniquely modulated by two rod proteins, FlgB and FlgF.
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41
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Herlihey FA, Clarke AJ. Controlling Autolysis During Flagella Insertion in Gram-Negative Bacteria. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 925:41-56. [PMID: 27722959 DOI: 10.1007/5584_2016_52] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The flagellum is an important macromolecular machine for many pathogenic bacteria. It is a hetero-oligomeric structure comprised of three major sub-structures: basal body, hook and thin helical filament. An important step during flagellum assembly is the localized and controlled degradation of the peptidoglycan sacculus to allow for the insertion of the rod as well as to facilitate anchoring for proper motor function. The peptidoglycan lysis events require specialized lytic enzymes, β-N-acetylglucosaminidases and lytic transglycosylases, which differ in flagellated proteobacteria. Due to their autolytic activity, these enzymes need to be controlled in order to prevent cellular lysis. This review summarizes are current understanding of the peptidoglycan lysis events required for flagellum assembly and motility with a main focus on Gram-negative bacteria.
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Affiliation(s)
- Francesca A Herlihey
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G2W1, Canada
| | - Anthony J Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G2W1, Canada.
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The Burkholderia pseudomallei Proteins BapA and BapC Are Secreted TTSS3 Effectors and BapB Levels Modulate Expression of BopE. PLoS One 2015; 10:e0143916. [PMID: 26624293 PMCID: PMC4666416 DOI: 10.1371/journal.pone.0143916] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 11/11/2015] [Indexed: 12/15/2022] Open
Abstract
Many Gram-negative pathogens use a type III secretion system (TTSS) for the injection of bacterial effector proteins into host cells. The injected effector proteins play direct roles in modulation of host cell pathways for bacterial benefit. Burkholderia pseudomallei, the causative agent of melioidosis, expresses three different TTSSs. One of these systems, the TTSS3, is essential for escape from host endosomes and therefore intracellular survival and replication. Here we have characterized three putative TTSS3 proteins; namely BapA, BapB and BapC. By employing a tetracysteine (TC)-FlAsH™ labelling technique to monitor the secretion of TC-tagged fusion proteins, BapA and BapC were shown to be secreted during in vitro growth in a TTSS3-dependant manner, suggesting a role as TTSS3 effectors. Furthermore, we constructed B. pseudomallei bapA, bapB and bapC mutants and used the well-characterized TTSS3 effector BopE as a marker of secretion to show that BapA, BapB and BapC are not essential for the secretion process. However, BopE transcription and secretion were significantly increased in the bapB mutant, suggesting that BapB levels modulate BopE expression. In a BALB/c mouse model of acute melioidosis, the bapA, bapB and bapC mutants showed a minor reduction of in vivo fitness. Thus, this study defines BapA and BapC as novel TTSS3 effectors, BapB as a regulator of BopE production, and all three as necessary for full B. pseudomallei in vivo fitness.
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Dong H, Zhu C, Chen J, Ye X, Huang YP. Antibacterial Activity of Stenotrophomonas maltophilia Endolysin P28 against both Gram-positive and Gram-negative Bacteria. Front Microbiol 2015; 6:1299. [PMID: 26635765 PMCID: PMC4656821 DOI: 10.3389/fmicb.2015.01299] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 11/06/2015] [Indexed: 01/09/2023] Open
Abstract
Maltocin P28 is a phage-tail like bacteriocin produced by Stenotrophomonas maltophilia P28. The ORF8 of maltocin P28 gene cluster is predicted to encode an endolysin and we name it endolysin P28. Sequence analysis revealed that it contains the lysozyme_like superfamily conserved domain. Endolysin P28 has the four consensus motifs as that of Escherichia coli phage lambda gpR. In this study, endolysin P28 was expressed in E. coli BL21 (DE3) and purified with a C-terminal oligo-histidine tag. The antibacterial activity of endolysin P28 increased as the temperature rose from 25 to 45°C. Thermostability assays showed that endolysin P28 was stable up to 50°C, while its residual activity was reduced by 55% after treatment at 70°C for 30 min. Acidity and high salinity could enhance its antibacterial activity. Endolysin P28 exhibited a broad antibacterial activity against 14 out of 16 tested Gram-positive and Gram-negative bacteria besides S. maltophilia. Moreover, it could effectively lyse intact Gram-negative bacteria in the absence of ethylenediaminetetraacetic acid as an outer membrane permeabilizer. Therefore, the characteristics of endolysin P28 make it a potential therapeutic agent against multi-drug-resistant pathogens.
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Affiliation(s)
- Hongling Dong
- College of Life Sciences, Wuhan University Wuhan, China
| | - Chaoyang Zhu
- College of Life Sciences, Wuhan University Wuhan, China
| | - Jingyi Chen
- College of Life Sciences, Wuhan University Wuhan, China
| | - Xing Ye
- College of Life Sciences, Wuhan University Wuhan, China
| | - Yu-Ping Huang
- College of Life Sciences, Wuhan University Wuhan, China ; Hubei Provincial Cooperative Innovation Center of Industrial Fermentation Wuhan, China
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Yunck R, Cho H, Bernhardt TG. Identification of MltG as a potential terminase for peptidoglycan polymerization in bacteria. Mol Microbiol 2015; 99:700-18. [PMID: 26507882 DOI: 10.1111/mmi.13258] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/12/2015] [Indexed: 12/27/2022]
Abstract
Bacterial cells are fortified against osmotic lysis by a cell wall made of peptidoglycan (PG). Synthases called penicillin-binding proteins (PBPs), the targets of penicillin and related antibiotics, polymerize the glycan strands of PG and crosslink them into the cell wall meshwork via attached peptides. The average length of glycan chains inserted into the matrix by the PBPs is thought to play an important role in bacterial morphogenesis, but polymerization termination factors controlling this process have yet to be discovered. Here, we report the identification of Escherichia coli MltG (YceG) as a potential terminase for glycan polymerization that is broadly conserved in bacteria. A clone containing mltG was initially isolated in a screen for multicopy plasmids generating a lethal phenotype in cells defective for the PG synthase PBP1b. Biochemical studies revealed that MltG is an inner membrane enzyme with endolytic transglycosylase activity capable of cleaving at internal positions within a glycan polymer. Radiolabeling experiments further demonstrated MltG-dependent nascent PG processing in vivo, and bacterial two-hybrid analysis identified an MltG-PBP1b interaction. Mutants lacking MltG were also shown to have longer glycans in their PG relative to wild-type cells. Our combined results are thus consistent with a model in which MltG associates with PG synthetic complexes to cleave nascent polymers and terminate their elongation.
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Affiliation(s)
- Rachel Yunck
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Hongbaek Cho
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Thomas G Bernhardt
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, 02115, USA
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Lamers RP, Nguyen UT, Nguyen Y, Buensuceso RNC, Burrows LL. Loss of membrane-bound lytic transglycosylases increases outer membrane permeability and β-lactam sensitivity in Pseudomonas aeruginosa. Microbiologyopen 2015; 4:879-95. [PMID: 26374494 PMCID: PMC4694138 DOI: 10.1002/mbo3.286] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 08/04/2015] [Accepted: 08/10/2015] [Indexed: 11/25/2022] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa is a leading cause of nosocomial infections. Its relatively impermeable outer membrane (OM) limits antibiotic entry, and a chromosomally encoded AmpC β‐lactamase inactivates β‐lactam antibiotics. AmpC expression is linked to peptidoglycan (PG) recycling, and soluble (sLT) or membrane‐bound (mLT) lytic transglycosylases are responsible for generating the anhydromuropeptides that induce AmpC expression. Thus, inhibition of LT activity could reduce AmpC‐mediated β‐lactam resistance in P. aeruginosa. Here, we characterized single and combination LT mutants. Strains lacking SltB1 or MltB had increased β‐lactam minimum inhibitory concentrations (MICs) compared to wild type, while only loss of Slt decreased MICs. An sltB1 mltB double mutant had elevated β‐lactam MICs compared to either the sltB1 or mltB single mutants (96 vs. 32 μg/mL cefotaxime), without changes to AmpC levels. Time–kill assays with β‐lactams suggested that increased MIC correlated with a slower rate of autolysis in the sltB1 mltB mutant – an antisuicide phenotype. Strains lacking multiple mLTs were more sensitive to β‐lactams and up to 16‐fold more sensitive to vancomycin, normally incapable of crossing the OM. Multi‐mLT mutants were also sensitive to bile salts and osmotic stress, and were hyperbiofilm formers, all phenotypes consistent with cell envelope compromise. Complementation with genes encoding inactive forms of the enzymes – or alternatively, overexpression of Braun's lipoprotein – reversed the mutants' cell envelope damage phenotypes, suggesting that mLTs help to stabilize the OM. We conclude that P. aeruginosa mLTs contribute physically to cell envelope stability, and that Slt is the preferred target for future development of LT inhibitors that could synergize with β‐lactams.
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Affiliation(s)
- Ryan P Lamers
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Uyen T Nguyen
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Ylan Nguyen
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Ryan N C Buensuceso
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Lori L Burrows
- Department of Biochemistry and Biomedical Sciences, Michael G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
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Lipski A, Hervé M, Lombard V, Nurizzo D, Mengin-Lecreulx D, Bourne Y, Vincent F. Structural and biochemical characterization of the β-N-acetylglucosaminidase from Thermotoga maritima: toward rationalization of mechanistic knowledge in the GH73 family. Glycobiology 2014; 25:319-30. [PMID: 25344445 DOI: 10.1093/glycob/cwu113] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Members of the GH73 glycosidase family cleave the β-1,4-glycosidic bond between the N-acetylglucosaminyl (GlcNAc) and N-acetylmuramyl (MurNAc) moieties in bacterial peptidoglycan. A catalytic mechanism has been proposed for members FlgJ, Auto, AcmA and Atl(WM) and the structural analysis of FlgJ and Auto revealed a conserved α/β fold reminiscent of the distantly related GH23 lysozyme. Comparison of the active site residues reveals variability in the nature of the catalytic general base suggesting two distinct catalytic mechanisms: an inverting mechanism involving two distant glutamate residues and a substrate-assisted mechanism involving anchimeric assistance by the C2-acetamido group of the GlcNAc moiety. Herein, we present the biochemical characterization and crystal structure of TM0633 from the hyperthermophilic bacterium Thermotoga maritima. TM0633 adopts the α/β fold of the family and displays β-N-acetylglucosaminidase activity on intact peptidoglycan sacculi. Site-directed mutagenesis identifies Glu34, Glu65 and Tyr118 as important residues for catalysis. A thorough bioinformatic analysis of the GH73 sequences identified five phylogenetic clusters. TM0633, FlgJ and Auto belong to a group of three clusters that conserve two carboxylate residues involved in a classical inverting acid-base mechanism. Members of the other two clusters lack a conserved catalytic general base supporting a substrate-assisted mechanism. Molecular modeling of representative members from each cluster suggests that variability in length of the β-hairpin region above the active site confers ligand-binding specificity and modulates the catalytic mechanisms within the GH73 family.
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Affiliation(s)
- Alexandra Lipski
- Laboratory for Biocrystallography and Structural Biology of Therapeutic Targets, Molecular and Structural Bases of Infectious Diseases, UMR 5086 CNRS and University of Lyon, 7 passage du Vercors, F-69367 Lyon Cedex 07, France CNRS, AFMB UMR7257, 163 avenue de luminy, 13288 Marseille cedex 09, France
| | - Mireille Hervé
- Laboratoire des Enveloppes Bactériennes et Antibiotiques, Institut de Biochimie et Biophysique Moléculaire et Cellulaire, UMR 8619 CNRS, Université de Paris-Sud, 91405 Orsay, France
| | - Vincent Lombard
- CNRS, AFMB UMR7257, 163 avenue de luminy, 13288 Marseille cedex 09, France Aix-Marseille University, AFMB UMR7257, 163 avenue de luminy, 13288 Marseille cedex 09, France
| | - Didier Nurizzo
- European Synchrotron Radiation Facility, Polygone Scientifique Louis Néel, 6 rue Jules Horowitz, 38000 Grenoble, France
| | - Dominique Mengin-Lecreulx
- Laboratoire des Enveloppes Bactériennes et Antibiotiques, Institut de Biochimie et Biophysique Moléculaire et Cellulaire, UMR 8619 CNRS, Université de Paris-Sud, 91405 Orsay, France
| | - Yves Bourne
- CNRS, AFMB UMR7257, 163 avenue de luminy, 13288 Marseille cedex 09, France Aix-Marseille University, AFMB UMR7257, 163 avenue de luminy, 13288 Marseille cedex 09, France
| | - Florence Vincent
- CNRS, AFMB UMR7257, 163 avenue de luminy, 13288 Marseille cedex 09, France Aix-Marseille University, AFMB UMR7257, 163 avenue de luminy, 13288 Marseille cedex 09, France
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Fu LL, Wang R, Wang Y, Lin J. Proteomic identification of responsive proteins of Vibrio parahaemolyticus under high hydrostatic pressure. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2014; 94:2630-2638. [PMID: 24473993 DOI: 10.1002/jsfa.6595] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 01/21/2014] [Accepted: 01/22/2014] [Indexed: 06/03/2023]
Abstract
BACKGROUND High hydrostatic pressure (HHP) processing is currently being used as a treatment for certain foods to inhibit spoilage organisms and control the presence of foodborne pathogens. In this study proteome profiles were performed by two-dimensional gel electrophoresis (2-DE) coupled with MALDI-TOF/TOF identification to determine the effects of HHP (50, 100, 150 and 200 MPa, each for 10 min) on Vibrio parahaemolyticus ATCC 17802 (∼8 log CFU mL⁻¹) in order to understand how it responds to mechanical stress injury. RESULTS Multiple comparisons of 2-DE revealed that the majority of changes in protein abundance occurred in a pressure-dependent fashion. A total of 18 differentially expressed protein spots were successfully identified by MALDI-TOF/TOF analysis. Moreover, quantitative RT-PCR and immunoblotting also substantiated the changes of transcriptional and translational levels of representative proteins. CONCLUSIONS Our results suggested that V. parahaemolyticus may respond to HHP treatment through suppression of membrane stability and functionality (PfaC, Alr2, MltA, PLA2 and PatH), depression of biosynthesis and cellular processes (NadB, PyrB and ArgB), decreased levels of transcription (RpoD) and translation (RpsA, RplJ and PheS), and effective activation of protein folding and stress-related elements (GroES, DnaK and GroEL). This study may provide insight into the nature of the cellular targets of high pressure and in high-pressure resistance mechanisms in V. parahaemolyticus.
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Affiliation(s)
- Ling-Lin Fu
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310035, P.R. China
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Herlihey FA, Moynihan PJ, Clarke AJ. The essential protein for bacterial flagella formation FlgJ functions as a β-N-acetylglucosaminidase. J Biol Chem 2014; 289:31029-42. [PMID: 25248745 DOI: 10.1074/jbc.m114.603944] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The flagellum is a major virulence factor of motile pathogenic bacteria. This structure requires more than 50 proteins for its biogenesis and function, one of which is FlgJ. Homologs of FlgJ produced by the β- and γ-proteobacteria, such as Salmonella enterica, Vibrio spp., and both Sphingomonas sp. and Pseudomonas spp. are bifunctional, possessing an N-terminal domain responsible for proper rod assembly and a C-terminal domain possessing peptidoglycan lytic activity. Despite the amount of research conducted on FlgJ from these and other bacteria over the past 15 years, no biochemical analysis had been conducted on any FlgJ and consequently confusion exists as to whether the enzyme is a peptidoglycan hydrolase or a lytic transglycosylase. In this study, we present the development of a novel assay for glycoside lytic enzymes and its use to provide the first enzymatic characterization of the lytic domain of FlgJ from S. enterica as the model enzyme. Surprisingly, FlgJ functions as neither a muramidase nor a lytic transglycosylases but rather as a β-N-acetylglucosaminidase. As such, FlgJ represents the first autolysin with this activity to be characterized from a Gram-negative bacterium. At its optimal pH of 4.0, the Michaelis-Menten parameters of K(m) and k(cat) for FlgJ from S. enterica were determined to be 0.64 ± 0.18 mg ml(-1) and 0.13 ± 0.016 s(-1), respectively, using purified PG as substrate. Its catalytic residues were identified as Glu(184) and Glu(223).
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Affiliation(s)
- Francesca A Herlihey
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Patrick J Moynihan
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Anthony J Clarke
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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Aminlari L, Hashemi MM, Aminlari M. Modified lysozymes as novel broad spectrum natural antimicrobial agents in foods. J Food Sci 2014; 79:R1077-90. [PMID: 24837015 DOI: 10.1111/1750-3841.12460] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 03/15/2014] [Indexed: 11/27/2022]
Abstract
UNLABELLED In recent years much attention and interest have been directed toward application of natural antimicrobial agents in foods. Some naturally occurring proteins such as lactoperoxidase, lactoferrin, and lysozyme have received considerable attention and are being considered as potential antimicrobial agents in foods. Lysozyme kills bacteria by hydrolyzing the peptidoglycan layer of the cell wall of certain bacterial species, hence its application as a natural antimicrobial agent has been suggested. However, limitations in the action of lysozyme against only Gram-positive bacteria have prompted scientists to extend the antimicrobial effects of lysozyme by several types of chemical modifications. During the last 2 decades extensive research has been directed toward modification of lysozyme in order to improve its antimicrobial properties. This review will report on the latest information available on lysozyme modifications and examine the applicability of the modified lysozymes in controlling growth of Gram-positive and Gram-negative bacteria in foods. The results of modifications of lysozyme using its conjugation with different small molecule, polysaccharides, as well as modifications using proteolytic enzymes will be reviewed. These types of modifications have not only increased the functional properties of lysozyme (such as solubility and heat stability) but also extended the antimicrobial activity of lysozyme. Many examples will be given to show that modification can decrease the count of Gram-negative bacteria in bacterial culture and in foods by as much as 5 log CFU/mL and in some cases essentially eliminated Escherichia coli. In conclusion this review demonstrates that modified lysozymes are excellent natural food preservatives, which can be used in food industry. PRACTICAL APPLICATION The subject described in this review article can lead to the development of methods to produce new broad-spectrum natural antimicrobial agents, based on modification of chicken egg white lysozyme, which might potentially replace the currently used synthetic food preservatives.
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Affiliation(s)
- Ladan Aminlari
- Dept. of Food Hygiene and Public Health, School of Veterinary Medicine, Shiraz Univ, Shiraz, Iran
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