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Field CJ, Bowerman KL, Hugenholtz P. Multiple independent losses of sporulation and peptidoglycan in the Mycoplasmatales and related orders of the class Bacilli. Microb Genom 2024; 10:001176. [PMID: 38189216 PMCID: PMC10868615 DOI: 10.1099/mgen.0.001176] [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: 10/24/2023] [Accepted: 12/19/2023] [Indexed: 01/09/2024] Open
Abstract
Many peptidoglycan-deficient bacteria such as the Mycoplasmatales are known host-associated lineages, lacking the environmental resistance mechanisms and metabolic capabilities necessary for a free-living lifestyle. Several peptidoglycan-deficient and non-sporulating orders of interest are thought to be descended from Gram-positive sporulating Bacilli through reductive evolution. Here we annotate 2650 genomes belonging to the class Bacilli, according to the Genome Taxonomy Database, to predict the peptidoglycan and sporulation phenotypes of three novel orders, RFN20, RF39 and ML615J-28, known only through environmental sequence surveys. These lineages are interspersed between peptidoglycan-deficient non-sporulating orders including the Mycoplasmatales and Acholeplasmatales, and more typical Gram-positive orders such as the Erysipelotrichales and Staphylococcales. We use the extant genotypes to perform ancestral state reconstructions. The novel orders are predicted to have small genomes with minimal metabolic capabilities and to comprise a mix of peptidoglycan-deficient and/or non-sporulating species. In contrast to expectations based on cultured representatives, the order Erysipelotrichales lacks many of the genes involved in peptidoglycan and endospore formation. The reconstructed evolutionary history of these traits suggests multiple independent whole-genome reductions and loss of phenotype via intermediate transition states that continue into the present. We suggest that the evolutionary history of the reduced-genome lineages within the class Bacilli is one driven by multiple independent transitions to host-associated lifestyles, with the degree of reduction in environmental resistance and metabolic capabilities correlated with degree of host association.
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Affiliation(s)
- Christian J. Field
- School of Chemistry and Molecular Biosciences, The Australian Centre for Ecogenomics, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Kate L. Bowerman
- School of Chemistry and Molecular Biosciences, The Australian Centre for Ecogenomics, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Philip Hugenholtz
- School of Chemistry and Molecular Biosciences, The Australian Centre for Ecogenomics, The University of Queensland, St Lucia, QLD 4072, Australia
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Setlow P, Christie G. New Thoughts on an Old Topic: Secrets of Bacterial Spore Resistance Slowly Being Revealed. Microbiol Mol Biol Rev 2023; 87:e0008022. [PMID: 36927044 PMCID: PMC10304885 DOI: 10.1128/mmbr.00080-22] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023] Open
Abstract
The quest for bacterial survival is exemplified by spores formed by some Firmicutes members. They turn up everywhere one looks, and their ubiquity reflects adaptations to the stresses bacteria face. Spores are impactful in public health, food safety, and biowarfare. Heat resistance is the hallmark of spores and is countered principally by a mineralized gel-like protoplast, termed the spore core, with reduced water which minimizes macromolecular movement/denaturation/aggregation. Dry heat, however, introduces mutations into spore DNA. Spores have countermeasures to extreme conditions that are multifactorial, but the fact that spore DNA is in a crystalline-like nucleoid in the spore core, likely due to DNA saturation with small acid-soluble spore proteins (SASPs), suggests that reduced macromolecular motion is also critical in spore dry heat resistance. SASPs are also central in the radiation resistance characteristic of spores, where the contributions of four spore features-SASP; Ca2+, with pyridine-2,6-dicarboxylic acid (CaDPA); photoproduct lyase; and low water content-minimize DNA damage. Notably, the spore environment steers UV photochemistry toward a product that germinated spores can repair without significant mutagenesis. This resistance extends to chemicals and macromolecules that could damage spores. Macromolecules are excluded by the spore coat which impedes the passage of moieties of ≥10 kDa. Additionally, damaging chemicals may be degraded or neutralized by coat enzymes/proteins. However, the principal protective mechanism here is the inner membrane, a compressed structure lacking lipid fluidity and presenting a barrier to the diffusion of chemicals into the spore core; SASP saturation of DNA also protects against genotoxic chemicals. Spores are also resistant to other stresses, including high pressure and abrasion. Regardless, overarching mechanisms associated with resistance seem to revolve around reduced molecular motion, a fine balance between rigidity and flexibility, and perhaps efficient repair.
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Affiliation(s)
- Peter Setlow
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
| | - Graham Christie
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
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Conservation and Evolution of the Sporulation Gene Set in Diverse Members of the Firmicutes. J Bacteriol 2022; 204:e0007922. [PMID: 35638784 DOI: 10.1128/jb.00079-22] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The current classification of the phylum Firmicutes (new name, Bacillota) features eight distinct classes, six of which include known spore-forming bacteria. In Bacillus subtilis, sporulation involves up to 500 genes, many of which do not have orthologs in other bacilli and/or clostridia. Previous studies identified about 60 sporulation genes of B. subtilis that were shared by all spore-forming members of the Firmicutes. These genes are referred to as the sporulation core or signature, although many of these are also found in genomes of nonsporeformers. Using an expanded set of 180 firmicute genomes from 160 genera, including 76 spore-forming species, we investigated the conservation of the sporulation genes, in particular seeking to identify lineages that lack some of the genes from the conserved sporulation core. The results of this analysis confirmed that many small acid-soluble spore proteins (SASPs), spore coat proteins, and germination proteins, which were previously characterized in bacilli, are missing in spore-forming members of Clostridia and other classes of Firmicutes. A particularly dramatic loss of sporulation genes was observed in the spore-forming members of the families Planococcaceae and Erysipelotrichaceae. Fifteen species from diverse lineages were found to carry skin (sigK-interrupting) elements of different sizes that all encoded SpoIVCA-like recombinases but did not share any other genes. Phylogenetic trees built from concatenated alignments of sporulation proteins and ribosomal proteins showed similar topology, indicating an early origin and subsequent vertical inheritance of the sporulation genes. IMPORTANCE Many members of the phylum Firmicutes (Bacillota) are capable of producing endospores, which enhance the survival of important Gram-positive pathogens that cause such diseases as anthrax, botulism, colitis, gas gangrene, and tetanus. We show that the core set of sporulation genes, defined previously through genome comparisons of several bacilli and clostridia, is conserved in a wide variety of sporeformers from several distinct lineages of Firmicutes. We also detected widespread loss of sporulation genes in many organisms, particularly within the families Planococcaceae and Erysipelotrichaceae. Members of these families, such as Lysinibacillus sphaericus and Clostridium innocuum, could be excellent model organisms for studying sporulation mechanisms, such as engulfment, formation of the spore coat, and spore germination.
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Xia R, Yang Y, Pan X, Gao C, Yao Y, Liu X, Teame T, Zhang F, Hu J, Ran C, Zhang Z, Liu-Clarke J, Zhou Z. Improving the production of AHL lactonase AiiO-AIO6 from Ochrobactrum sp. M231 in intracellular protease-deficient Bacillus subtilis. AMB Express 2020; 10:138. [PMID: 32757095 PMCID: PMC7406587 DOI: 10.1186/s13568-020-01075-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 07/28/2020] [Indexed: 12/25/2022] Open
Abstract
Quorum quenching (QQ) blocks bacterial cell-to-cell communication (i.e., quorum sensing), and is a promising antipathogenic strategy to control bacterial infection via inhibition of virulence factor expression and biofilm formation. QQ enzyme AiiO-AIO6 from Ochrobactrum sp. M231 has several excellent properties and shows biotherapeutic potential against important bacterial pathogens of aquatic species. AiiO-AIO6 can be secretory expressed in Bacillus subtilis via a non-classical secretion pathway. To improve AiiO-AIO6 production, four intracellular protease-deletion mutants of B. subtilis 1A751 were constructed by individually knocking out the intracellular protease-encoding genes (tepA, ymfH, yrrN and ywpE). The AiiO-AIO6 expression plasmid pWB-AIO6BS was transformed into the B. subtilis 1A751 and its four intracellular protease-deletion derivatives. Results showed that all recombinant intracellular protease-deletion derivatives (BSΔtepA, BSΔymfH, BSΔyrrN and BSΔywpE) had a positive impact on AiiO-AIO6 production. The highest amount of AiiO-AIO6 extracellular production of BSΔywpE in shake flask reached 1416.47 U/mL/OD600, which was about 121% higher than that of the wild-type strain. Furthermore, LC-MS/MS analysis of the degrading products of 3-oxo-C8-HSL by purification of AiiO-AIO6 indicated that AiiO-AIO6 was an AHL-lactonase which hydrolyzes the lactone ring of AHLs. Phylogenetic analysis showed that AiiO-AIO6 was classified as a member of the α/β hydrolase family with a conserved "nucleophile-acid-histidine" catalytic triad. In summary, this study showed that intracellular proteases were responsible for the reduced yields of heterologous proteins and provided an efficient strategy to enhance the extracellular production of AHL lactonase AiiO-AIO6.
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Veatch AV, Kaushal D. Opening Pandora's Box: Mechanisms of Mycobacterium tuberculosis Resuscitation. Trends Microbiol 2017; 26:145-157. [PMID: 28911979 DOI: 10.1016/j.tim.2017.08.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 07/12/2017] [Accepted: 08/03/2017] [Indexed: 12/27/2022]
Abstract
Mycobacterium tuberculosis (Mtb) characteristically causes an asymptomatic infection. While this latent tuberculosis infection (LTBI) is not contagious, reactivation to active tuberculosis disease (TB) causes the patient to become infectious. A vaccine has existed for TB for a century, while drug treatments have been available for over 70 years; despite this, TB remains a major global health crisis. Understanding the factors which allow the bacillus to control responses to host stress and mechanisms leading to latency are critical for persistence. Similarly, molecular switches which respond to reactivation are important. Recently, research in the field has sought to focus on reactivation, employing system-wide approaches and animal models. Here, we describe the current work that has been done to elucidate the mechanisms of reactivation and stop reactivation in its tracks.
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Affiliation(s)
- Ashley V Veatch
- Divisions of Bacteriology and Parasitology, Tulane National Primate Research Center, Covington, LA, USA; Department of Microbiology & Immunology, Tulane University School of Medicine, New Orleans, LA, USA
| | - Deepak Kaushal
- Divisions of Bacteriology and Parasitology, Tulane National Primate Research Center, Covington, LA, USA; Department of Microbiology & Immunology, Tulane University School of Medicine, New Orleans, LA, USA.
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Cai D, Wang H, He P, Zhu C, Wang Q, Wei X, Nomura CT, Chen S. A novel strategy to improve protein secretion via overexpression of the SppA signal peptide peptidase in Bacillus licheniformis. Microb Cell Fact 2017; 16:70. [PMID: 28438200 PMCID: PMC5404308 DOI: 10.1186/s12934-017-0688-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 04/21/2017] [Indexed: 12/21/2022] Open
Abstract
Background Signal peptide peptidases play an important role in the removal of remnant signal peptides in the cell membrane, a critical step for extracellular protein production. Although these proteins are likely a central component for extracellular protein production, there has been a lack of research on whether protein secretion could be enhanced via overexpression of signal peptide peptidases. Results In this study, both nattokinase and α-amylase were employed as prototypical secreted target proteins to evaluate the function of putative signal peptide peptidases (SppA and TepA) in Bacillus licheniformis. We observed dramatic decreases in the concentrations of both target proteins (45 and 49%, respectively) in a sppA deficient strain, while the extracellular protein yields of nattokinase and α-amylase were increased by 30 and 67% respectively in a strain overexpressing SppA. In addition, biomass, specific enzyme activities and the relative gene transcriptional levels were also enhanced due to the overexpression of sppA, while altering the expression levels of tepA had no effect on the concentrations of the secreted target proteins. Conclusions Our results confirm that SppA, but not TepA, plays an important functional role for protein secretion in B. licheniformis. Our results indicate that the sppA overexpression strain, B. licheniformis BL10GS, could be used as a promising host strain for the industrial production of heterologous secreted proteins. Electronic supplementary material The online version of this article (doi:10.1186/s12934-017-0688-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Dongbo Cai
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, No. 368 Youyi Avenue, Wuchang District, Wuhan, 430062, Hubei, People's Republic of China
| | - Hao Wang
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, No. 368 Youyi Avenue, Wuchang District, Wuhan, 430062, Hubei, People's Republic of China
| | - Penghui He
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, No. 368 Youyi Avenue, Wuchang District, Wuhan, 430062, Hubei, People's Republic of China
| | - Chengjun Zhu
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, No. 368 Youyi Avenue, Wuchang District, Wuhan, 430062, Hubei, People's Republic of China
| | - Qin Wang
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, No. 368 Youyi Avenue, Wuchang District, Wuhan, 430062, Hubei, People's Republic of China
| | - Xuetuan Wei
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Christopher T Nomura
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, No. 368 Youyi Avenue, Wuchang District, Wuhan, 430062, Hubei, People's Republic of China.,Department of Chemistry, The State University of New York College of Environmental Science and Forestry (SUNY ESF), Syracuse, NY, 13210, USA
| | - Shouwen Chen
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, No. 368 Youyi Avenue, Wuchang District, Wuhan, 430062, Hubei, People's Republic of China.
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Zheng L, Abhyankar W, Ouwerling N, Dekker HL, van Veen H, van der Wel NN, Roseboom W, de Koning LJ, Brul S, de Koster CG. Bacillus subtilis Spore Inner Membrane Proteome. J Proteome Res 2016; 15:585-94. [PMID: 26731423 DOI: 10.1021/acs.jproteome.5b00976] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The endospore is the dormant form of Bacillus subtilis and many other Firmicutes. By sporulation, these spore formers can survive very harsh physical and chemical conditions. Yet, they need to go through germination to return to their growing form. The spore inner membrane (IM) has been shown to play an essential role in triggering the initiation of germination. In this study, we isolated the IM of bacterial spores, in parallel with the isolation of the membrane of vegetative cells. With the use of GeLC-MS/MS, over 900 proteins were identified from the B. subtilis spore IM preparations. By bioinformatics-based membrane protein predictions, ca. one-third could be predicted to be membrane-localized. A large number of unique proteins as well as proteins common to the two membrane proteomes were identified. In addition to previously known IM proteins, a number of IM proteins were newly identified, at least some of which are likely to provide new insights into IM physiology, unveiling proteins putatively involved in spore germination machinery and hence putative germination inhibition targets.
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Affiliation(s)
| | | | | | | | - Henk van Veen
- Electron Microscopy Centre Amsterdam, Department of Cell Biology and Histology, Academic Medical Center , 1105 AZ Amsterdam, The Netherlands
| | - Nicole N van der Wel
- Electron Microscopy Centre Amsterdam, Department of Cell Biology and Histology, Academic Medical Center , 1105 AZ Amsterdam, The Netherlands
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Wetzel D, Fischer RJ. Small acid-soluble spore proteins of Clostridium acetobutylicum are able to protect DNA in vitro and are specifically cleaved by germination protease GPR and spore protease YyaC. MICROBIOLOGY-SGM 2015; 161:2098-109. [PMID: 26362088 DOI: 10.1099/mic.0.000162] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Small acid-soluble proteins (SASPs) play an important role in protection of DNA in dormant bacterial endospores against damage by heat, UV radiation or enzymic degradation. In the genome of the strict anaerobe Clostridium acetobutylicum, five genes encoding SASPs have been annotated and here a further sixth candidate is suggested. The ssp genes are expressed in parallel dependent upon Spo0A, a master regulator of sporulation. Analysis of the transcription start points revealed a σG or a σF consensus promoter upstream of each ssp gene, confirming a forespore-specific gene expression. SASPs were termed SspA (Cac2365), SspB (Cac1522), SspD (Cac1620), SspF (Cac2372), SspH (Cac1663) and Tlp (Cac1487). Here it is shown that with the exception of Tlp, every purified recombinant SASP is able to bind DNA in vitro thereby protecting it against enzymic degradation by DNase I. Moreover, SspB and SspD were specifically cleaved by the two germination-specific proteases GPR (Cac1275) and YyaC (Cac2857), which were overexpressed in Escherichia coli and activated by an autocleavage reaction. Thus, for the first time to our knowledge, GPR-like activity and SASP specificity could be demonstrated for a YyaC-like protein. Collectively, the results assign SspA, SspB, SspD, SspF and SspH of C. acetobutylicum as members of α/β-type SASPs, whereas Tlp seems to be a non-DNA-binding spore protein of unknown function. In acetic acid-extracted proteins of dormant spores of C. acetobutylicum, SspA was identified almost exclusively, indicating its dominant biological role as a major α/β-type SASP in vivo.
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Affiliation(s)
- Daniela Wetzel
- Abteilung für Mikrobiologie, Institut für Biowissenschaften, Universität Rostock, Albert-Einstein-Str. 3, D-18051 Rostock, Germany
| | - Ralf-Jörg Fischer
- Abteilung für Mikrobiologie, Institut für Biowissenschaften, Universität Rostock, Albert-Einstein-Str. 3, D-18051 Rostock, Germany
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