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Guerrero M. GG. Sporulation, Structure Assembly, and Germination in the Soil Bacterium Bacillus thuringiensis: Survival and Success in the Environment and the Insect Host. MICROBIOLOGY RESEARCH 2023. [DOI: 10.3390/microbiolres14020035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023] Open
Abstract
Bacillus thuringiensis (Bt) is a rod-shaped, Gram-positive soil bacterium that belongs to the phylum Firmicutes and the genus Bacillus. It is a spore-forming bacterium. During sporulation, it produces a wide range of crystalline proteins that are toxic to different orders of insects. Sporulation, structure assembly, and germination are essential stages in the cell cycle of B. thuringiensis. The majority of studies on these issues have focused on the model organism Bacillus subtilis, followed by Bacillus cereus and Bacillus anthracis. The machinery for sporulation and germination extrapolated to B. thuringiensis. However, in the light of recent findings concerning the role of the sporulation proteins (SPoVS), the germination receptors (Gr), and the cortical enzymes in Bt, the theory strengthened that conservation in sporulation, structure assembly, and germination programs drive the survival and success of B. thuringiensis in the environment and the insect host. In the present minireview, the latter pinpointed and reviewed.
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Affiliation(s)
- Gloria G. Guerrero M.
- Unidad Académica de Ciencias Biológicas, Laboratorio de Immunobiología, Universidad Autónoma de Zacatecas, Av. Preparatoria S/N, Col. Agronomicas, Zacatecas 98066, Mexico
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Research Progress on the Effect of Autolysis to Bacillus subtilis Fermentation Bioprocess. FERMENTATION 2022. [DOI: 10.3390/fermentation8120685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Bacillus subtilis is a gram-positive bacterium, a promising microorganism due to its strong extracellular protein secretion ability, non-toxic, and relatively mature industrial fermentation technology. However, cell autolysis during fermentation restricts the industrial application of B. subtilis. With the fast advancement of molecular biology and genetic engineering technology, various advanced procedures and gene editing tools have been used to successfully construct autolysis-resistant B. subtilis chassis cells to manufacture various biological products. This paper first analyses the causes of autolysis in B. subtilis from a mechanistic perspective and outlines various strategies to address autolysis in B. subtilis. Finally, potential strategies for solving the autolysis problem of B. subtilis are foreseen.
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Genetic Screens Identify Additional Genes Implicated in Envelope Remodeling during the Engulfment Stage of Bacillus subtilis Sporulation. mBio 2022; 13:e0173222. [PMID: 36066101 PMCID: PMC9600426 DOI: 10.1128/mbio.01732-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During bacterial endospore formation, the developing spore is internalized into the mother cell through a phagocytic-like process called engulfment, which involves synthesis and hydrolysis of peptidoglycan. Engulfment peptidoglycan hydrolysis requires the widely conserved and well-characterized DMP complex, composed of SpoIID, SpoIIM, and SpoIIP. In contrast, although peptidoglycan synthesis has been implicated in engulfment, the protein players involved are less well defined. The widely conserved SpoIIIAH-SpoIIQ interaction is also required for engulfment efficiency, functioning like a ratchet to promote membrane migration around the forespore. Here, we screened for additional factors required for engulfment using transposon sequencing in Bacillus subtilis mutants with mild engulfment defects. We discovered that YrvJ, a peptidoglycan hydrolase, and the MurA paralog MurAB, involved in peptidoglycan precursor synthesis, are required for efficient engulfment. Cytological analyses suggest that both factors are important for engulfment when the DMP complex is compromised and that MurAB is additionally required when the SpoIIIAH-SpoIIQ ratchet is abolished. Interestingly, despite the importance of MurAB for sporulation in B. subtilis, phylogenetic analyses of MurA paralogs indicate that there is no correlation between sporulation and the number of MurA paralogs and further reveal the existence of a third MurA paralog, MurAC, within the Firmicutes. Collectively, our studies identify two new factors that are required for efficient envelop remodeling during sporulation and highlight the importance of peptidoglycan precursor synthesis for efficient engulfment in B. subtilis and likely other endospore-forming bacteria.
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Identification and Functional Characterization of Two Homologous SpoVS Proteins Involved in Sporulation of Bacillus thuringiensis. Microbiol Spectr 2021; 9:e0088121. [PMID: 34612699 PMCID: PMC8510167 DOI: 10.1128/spectrum.00881-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Sporulation is an important part of the life cycle of Bacillus thuringiensis and the basis for the production of parasporal crystals. This study identifies and characterizes two homologous spoVS genes (spoVS1 and spoVS2) in B. thuringiensis, both of whose expression is dependent on the σH factor. The disruption of spoVS1 and spoVS2 resulted in defective B. thuringiensis sporulation. Similar to Bacillus subtilis, B. thuringiensis strain HD(ΔspoVS1) mutants showed delayed formation of the polar septa, decreased sporulation efficiency, and blocked spore release. Different from B. subtilis, B. thuringiensis HD(ΔspoVS1) mutants had disporic septa and failed to complete engulfment in some cells. Moreover, HD(ΔspoVS2) mutants had delayed spore release. The effect of spoVS1 deletion on polar septum delay and sporulation efficiency could be compensated by spoVS2. β-Galactosidase activity analysis showed that the expression of pro-sigE and spoIIE decreased to different degrees in the HD(ΔspoVS1) and HD(ΔspoVS2) mutants. The different effects of the two mutations on the expression of sporulation genes led to decreases in Cry1Ac production of different levels. IMPORTANCE There is only one spoVS gene in B. subtilis, and its effects on sporulation have been reported. In this study, two homologous spoVS genes were found and identified in B. thuringiensis. The different effects on sporulation and parasporal crystal protein production in B. thuringiensis and their relationship were investigated. We found that these two homologous spoVS genes are highly conserved in the Bacillus cereus group, and therefore, the functional characterization of SpoVS is helpful to better understand the sporulation processes of members of the Bacillus cereus group.
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Leiser OP, Blackburn JK, Hadfield TL, Kreuzer HW, Wunschel DS, Bruckner-Lea CJ. Laboratory strains of Bacillus anthracis exhibit pervasive alteration in expression of proteins related to sporulation under laboratory conditions relative to genetically related wild strains. PLoS One 2018; 13:e0209120. [PMID: 30557394 PMCID: PMC6296524 DOI: 10.1371/journal.pone.0209120] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 11/20/2018] [Indexed: 11/25/2022] Open
Abstract
The spore forming pathogen Bacillus anthracis is the etiologic agent of anthrax in humans and animals. It cycles through infected hosts as vegetative cells and is eventually introduced into the environment where it generates an endospore resistant to many harsh conditions. The endospores are subsequently taken up by another host to begin the next cycle. Outbreaks of anthrax occur regularly worldwide in wildlife and livestock, and the potential for human infection exists whenever humans encounter infected animals. It is also possible to encounter intentional releases of anthrax spores, as was the case in October 2001. Consequently, it is important to be able to rapidly establish the provenance of infectious strains of B. anthracis. Here, we compare protein expression in seven low-passage wild isolates and four laboratory strains of B. anthracis grown under identical conditions using LC-MS/MS proteomic analysis. Of the 1,023 total identified proteins, 96 had significant abundance differences between wild and laboratory strains. Of those, 28 proteins directly related to sporulation were upregulated in wild isolates, with expression driven by Spo0A, CodY, and AbrB/ScoC. In addition, we observed evidence of changes in cell division and fatty acid biosynthesis between the two classes of strains, despite being grown under identical experimental conditions. These results suggest wild B. anthracis cells are more highly tuned to sporulate than their laboratory cousins, and this difference should be exploited as a method to differentiate between laboratory and low passage wild strains isolated during an anthrax outbreak. This knowledge should distinguish between intentional releases and exposure to strains in nature, providing a basis for the type of response by public health officials and investigators.
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Affiliation(s)
- Owen P. Leiser
- Chemical and Biological Signature Science, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Jason K. Blackburn
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
- Spatial Epidemiology & Ecology Research Laboratory, Department of Geography, University of Florida, Gainesville, Florida, United States of America
| | - Ted L. Hadfield
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
- Spatial Epidemiology & Ecology Research Laboratory, Department of Geography, University of Florida, Gainesville, Florida, United States of America
| | - Helen W. Kreuzer
- Chemical and Biological Signature Science, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - David S. Wunschel
- Chemical and Biological Signature Science, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Cindy J. Bruckner-Lea
- Chemical and Biological Signature Science, Pacific Northwest National Laboratory, Richland, Washington, United States of America
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Jutras BL, Chenail AM, Rowland CL, Carroll D, Miller MC, Bykowski T, Stevenson B. Eubacterial SpoVG homologs constitute a new family of site-specific DNA-binding proteins. PLoS One 2013; 8:e66683. [PMID: 23818957 PMCID: PMC3688583 DOI: 10.1371/journal.pone.0066683] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 05/09/2013] [Indexed: 01/06/2023] Open
Abstract
A site-specific DNA-binding protein was purified from Borrelia burgdorferi cytoplasmic extracts, and determined to be a member of the highly conserved SpoVG family. This is the first time a function has been attributed to any of these ubiquitous bacterial proteins. Further investigations into SpoVG orthologues indicated that the Staphylococcus aureus protein also binds DNA, but interacts preferentially with a distinct nucleic acid sequence. Site-directed mutagenesis and domain swapping between the S. aureus and B. burgdorferi proteins identified that a 6-residue stretch of the SpoVG α-helix contributes to DNA sequence specificity. Two additional, highly conserved amino acid residues on an adjacent β-sheet are essential for DNA-binding, apparently by contacts with the DNA phosphate backbone. Results of these studies thus identified a novel family of bacterial DNA-binding proteins, developed a model of SpoVG-DNA interactions, and provide direction for future functional studies on these wide-spread proteins.
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Affiliation(s)
- Brandon L. Jutras
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Alicia M. Chenail
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Christi L. Rowland
- Department of Agricultural Sciences, University of Kentucky College of Agriculture, Lexington, Kentucky, United States of America
| | - Dustin Carroll
- Graduate Center for Toxicology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - M. Clarke Miller
- Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America
| | - Tomasz Bykowski
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Brian Stevenson
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
- * E-mail:
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The σB-dependent yabJ-spoVG operon is involved in the regulation of extracellular nuclease, lipase, and protease expression in Staphylococcus aureus. J Bacteriol 2011; 193:4954-62. [PMID: 21725011 DOI: 10.1128/jb.05362-11] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The alternative sigma factor σ(B) of Staphylococcus aureus is involved in the coordination of the general stress response, expression of virulence determinants, and modulation of antibiotic resistance levels. It controls a large regulon, either directly by recognizing conserved σ(B) promoter sequences or indirectly via σ(B)-dependent elements. The σ(B)-controlled yabJ-spoVG operon encodes two such putative downstream elements. We report here transcriptome analysis in S. aureus Newman, showing that inactivation of the yabJ-spoVG operon had primarily a repressing effect on a small subregulon encoding mainly virulence factors, including a nuclease (nuc), a protease (splE) and a lipase (lip). As a consequence, extracellular nuclease, protease, and lipase activities were reduced in a ΔyabJ-spoVG mutant. trans-complementation by SpoVG was sufficient to restore their reduced phenotypic expression and lowered transcription due to the yabJ-spoVG deletion. It did not restore, however, the changes triggered by σ(B) inactivation, indicating that both regulons only partially overlap, despite the σ(B) dependency of the yabJ-spoVG expression. Thus, σ(B) is likely to control additional, SpoVG-independent factors affecting the expression of numerous hydrolytic enzymes. SpoVG, on the other hand, seems to fine-tune the σ(B)-dependent regulation of a subset of virulence factors by antagonizing the σ(B) effect.
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SpoIID-mediated peptidoglycan degradation is required throughout engulfment during Bacillus subtilis sporulation. J Bacteriol 2010; 192:3174-86. [PMID: 20382772 DOI: 10.1128/jb.00127-10] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SpoIID is a membrane-anchored enzyme that degrades peptidoglycan and is essential for engulfment and sporulation in Bacillus subtilis. SpoIID is targeted to the sporulation septum, where it interacts with two other proteins required for engulfment: SpoIIP and SpoIIM. We changed conserved amino acids in SpoIID to alanine to determine whether there was a correlation between the effect of each substitution on the in vivo and in vitro activities of SpoIID. We identified one amino acid substitution, E88A, that eliminated peptidoglycan degradation activity and one, D210A, that reduced it, as well as two substitutions that destabilized the protein in B. subtilis (R106A and K203A). Using these mutants, we show that the peptidoglycan degradation activity of SpoIID is required for the first step of engulfment (septal thinning), as well as throughout membrane migration, and we show that SpoIID levels are substantially above the minimum required for engulfment. The inactive mutant E88A shows increased septal localization compared to the wild type, suggesting that the degradation cycle of the SpoIID/SpoIIP complex is accompanied by the activity-dependent release of SpoIID from the complex and subsequent rebinding. This mutant is also capable of moving SpoIIP across the sporulation septum, suggesting that SpoIID binding, but not peptidoglycan degradation activity, is needed for relocalization of SpoIIP. Finally, the mutant with reduced activity (D210A) causes uneven engulfment and time-lapse microscopy indicates that the fastest-moving membrane arm has greater concentrations of SpoIIP than the slower-moving arm, demonstrating a correlation between SpoIIP protein levels and the rate of membrane migration.
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Role of the sigmaD-dependent autolysins in Bacillus subtilis population heterogeneity. J Bacteriol 2009; 191:5775-84. [PMID: 19542270 DOI: 10.1128/jb.00521-09] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Exponentially growing populations of Bacillus subtilis contain two morphologically and functionally distinct cell types: motile individuals and nonmotile multicellular chains. Motility differentiation arises because RNA polymerase and the alternative sigma factor sigma(D) activate expression of flagellin in a subpopulation of cells. Here we demonstrate that the peptidoglycan-remodeling autolysins under sigma(D) control, LytC, LytD, and LytF, are expressed in the same subpopulation of cells that complete flagellar synthesis. Morphological heterogeneity is explained by the expression of LytF that is necessary and sufficient for cell separation. Moreover, LytC is required for motility but not at the level of cell separation or flagellum biosynthesis. Rather, LytC appears to be important for flagellar function, and motility was restored to a LytC mutant by mutation of either lonA, encoding the LonA protease, or a gene encoding a previously unannotated swarming motility inhibitor, SmiA. We conclude that heterogeneous activation of sigma(D)-dependent gene expression is sufficient to explain both the morphological heterogeneity and functional heterogeneity present in vegetative B. subtilis populations.
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Transcriptome divergence and the loss of plasticity in Bacillus subtilis after 6,000 generations of evolution under relaxed selection for sporulation. J Bacteriol 2008; 191:428-33. [PMID: 18952793 DOI: 10.1128/jb.01234-08] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We used microarrays to identify the causes of sporulation deficiencies in Bacillus subtilis after 6,000 generations of evolution. We found that sporulation loss did not result from large-scale deletions; therefore, it must have resulted from smaller indels and/or substitutions. Transcription patterns of one strain versus its ancestor showed that sporulation was not initiated and suggested that sporulation loss may be part of an overall decline in plasticity.
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Rigden DJ, Galperin MY. Sequence analysis of GerM and SpoVS, uncharacterized bacterial 'sporulation' proteins with widespread phylogenetic distribution. ACTA ACUST UNITED AC 2008; 24:1793-7. [PMID: 18562273 PMCID: PMC2732212 DOI: 10.1093/bioinformatics/btn314] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
UNLABELLED Sporulation in low-G+C gram-positive bacteria (Firmicutes) is an important survival mechanism that involves up to 150 genes, acting in a highly regulated manner. Many sporulation genes have close homologs in non-sporulating bacteria, including cyanobacteria, proteobacteria and spirochaetes, indicating that their products play a wider biological role. Most of them have been characterized as regulatory proteins or enzymes of peptidoglycan turnover; functions of others remain unknown but they are likely to have a general role in cell division and/or development. We have compiled a list of such widely conserved sporulation and germination proteins with poorly characterized functions, ranked them by the width of their phylogenetic distribution, and performed detailed sequence analysis and, where possible, structural modeling aimed at estimating their potential functions. Here we report the results of sequence analysis of Bacillus subtilis spore germination protein GerM, suggesting that it is a widespread cell development protein, whose function might involve binding to peptidoglycan. GerM consists of two tandem copies of a new domain (designated the GERMN domain) that forms phylum-specific fusions with two other newly described domains, GERMN-associated domains 1 and 2 (GMAD1 and GMAD2). Fold recognition reveals a beta-propeller fold for GMAD1, while ab initio modeling suggests that GMAD2 adopts a fibronectin type III fold. SpoVS is predicted to adopt the AlbA archaeal chromatin protein fold, which suggests that it is a DNA-binding protein, most likely a novel transcriptional regulator. SUPPLEMENTARY INFORMATION Supplementary data are available at ftp://ftp.ncbi.nih.gov/pub/galperin/Sporulation.html.
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Affiliation(s)
- Daniel J Rigden
- School of Biological Sciences, University of Liverpool, Crown St, Liverpool L69 7ZB, UK.
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Chastanet A, Losick R. Engulfment during sporulation in Bacillus subtilis is governed by a multi-protein complex containing tandemly acting autolysins. Mol Microbiol 2007; 64:139-52. [PMID: 17376078 DOI: 10.1111/j.1365-2958.2007.05652.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The conversion of a growing cell into an endospore in Bacillus subtilis involves a phagocytic-like process in which the developing spore (the forespore) is wholly engulfed by the adjacent mother cell. A prerequisite for engulfment is the removal of peptidoglycan from the septum that separates the forespore from the mother cell, a process that depends on the autolysin SpoIID and two proteins of unknown function, SpoIIM and SpoIIP. Here we present evidence that SpoIIP is also an autolysin, that it acts in tandem with SpoIID, and that all three proteins are in a complex with each other. We further show that the members of the complex exhibit a hierarchical relationship in which SpoIIM is responsible for localization to the septal membrane, SpoIIP localizes to the septal membrane by interacting with SpoIIM, and SpoIID, in turn, localizes by interacting with SpoIIP. Finally, we show that localization of SpoIIM depends on a fourth protein SpoIIB, raising the possibility that the complex contains an additional component and creating an overall hierarchy of the form: SpoIIB-->SpoIIM-->SpoIIP-->SpoIID.
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Affiliation(s)
- Arnaud Chastanet
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
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Broder DH, Pogliano K. Forespore engulfment mediated by a ratchet-like mechanism. Cell 2006; 126:917-28. [PMID: 16959571 PMCID: PMC3266857 DOI: 10.1016/j.cell.2006.06.053] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Revised: 05/17/2006] [Accepted: 06/23/2006] [Indexed: 10/24/2022]
Abstract
A key step in bacterial endospore formation is engulfment, during which one bacterial cell engulfs another in a phagocytosis-like process that normally requires SpoIID, SpoIIM, and SpoIIP (DMP). We here describe a second mechanism involving the zipper-like interaction between the forespore protein SpoIIQ and its mother cell ligand SpoIIIAH, which are essential for engulfment when DMP activity is reduced or SpoIIB is absent. They are also required for the rapid engulfment observed during the enzymatic removal of peptidoglycan, a process that does not require DMP. These results suggest the existence of two separate engulfment machineries that compensate for one another in intact cells, thereby rendering engulfment robust. Photobleaching analysis demonstrates that SpoIIQ assembles a stationary structure, suggesting that SpoIIQ and SpoIIIAH function as a ratchet that renders forward membrane movement irreversible. We suggest that ratchet-mediated engulfment minimizes the utilization of chemical energy during this dramatic cellular reorganization, which occurs during starvation.
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Affiliation(s)
- Dan H. Broder
- Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA
| | - Kit Pogliano
- Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA
- Contact:
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