Identification of a Receptor Subunit and Putative Ligand-Binding Residues Involved in the
            <i>Bacillus megaterium</i>
            QM B1551 Spore Germination Response to Glucose

Christie, Graham; Götzke, Hansjörg; Lowe, Christopher R.

doi:10.1128/jb.00335-10

Cited by 32 publications

(31 citation statements)

References 48 publications

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“…Previous studies on the pBM700 germination (ger) operons have helped identify specific amino acid residues that define receptor specificity to germinant compounds in Bacillus (11,12). Strains of QM B1551 cured of pBM700 can no longer germinate on single germinant compounds (55), and the complete germination operon, with gerUA, gerUC, and gerUB and including the downstream monocistronic gene gerVB (BMQ_pBM70070 to BMQ_pBM70073), has been identified (10,12).…”

Section: Resultsmentioning

confidence: 99%

“…The French microbiologist Maurice Lemoigne in 1925 discovered the polyester polyhydroxybutyrate in B. megaterium as an important energy storage molecule in bacteria (32), and Andre Lwoff discovered UV induction of bacteriophage in a lysogenic B. megaterium strain (35). Due to its large cell size, B. megaterium is well-suited for research on cell morphology, such as cell wall and cytoplasmic membrane biosynthesis, sporulation, spore structure and cellular organization, DNA partitioning, and protein localization (10,61). In the 1960s, B. megaterium was used to study sporulation, since it sporulates and germinates efficiently (18).…”

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confidence: 99%

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Genome Sequences of the Biotechnologically Important Bacillus megaterium Strains QM B1551 and DSM319

et al. 2011

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Bacillus megaterium is deep-rooted in the Bacillus phylogeny, making it an evolutionarily key species and of particular importance in understanding genome evolution, dynamics, and plasticity in the bacilli. B. megaterium is a commercially available, nonpathogenic host for the biotechnological production of several substances, including vitamin B 12 , penicillin acylase, and amylases. Here, we report the analysis of the first complete genome sequences of two important B. megaterium strains, the plasmidless strain DSM319 and QM B1551, which harbors seven indigenous plasmids. The 5.1-Mbp chromosome carries approximately 5,300 genes, while QM B1551 plasmids represent a combined 417 kb and 523 genes, one of the largest plasmid arrays sequenced in a single bacterial strain. We have documented extensive gene transfer between the plasmids and the chromosome. Each strain carries roughly 300 strain-specific chromosomal genes that account for differences in their experimentally confirmed phenotypes. B. megaterium is able to synthesize vitamin B 12 through an oxygen-independent adenosylcobalamin pathway, which together with other key energetic and metabolic pathways has now been fully reconstructed. Other novel genes include a second ftsZ gene, which may be responsible for the large cell size of members of this species, as well as genes for gas vesicles, a second ␤-galactosidase gene, and most but not all of the genes needed for genetic competence. Comprehensive analyses of the global Bacillus gene pool showed that only an asymmetric region around the origin of replication was syntenic across the genus. This appears to be a characteristic feature of the Bacillus spp. genome architecture and may be key to their sporulating lifestyle.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Genome Sequences of the Biotechnologically Important Bacillus megaterium Strains QM B1551 and DSM319

et al. 2011

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“…It seems certain that it is the GRs that bind nutrient germinants, since a number of specific mutations in GR subunits affect the apparent affinity of the mutant GR for specific germinants (4,22,23,57). Similarly, spores with elevated levels of specific GRs germinate more effectively with low germinant concentrations (4).…”

Section: Major Unanswered Questions About Spore Germination By Nutrientsmentioning

confidence: 99%

“…For example, with B. subtilis spores, L-alanine, L-valine, and L-asparagine trigger germination, while the D-amino acids are inert (20,21). In addition, specific amino acid changes in GR subunits can alter either the specificity or concentration dependence of a GR's response to a nutrient germinant (22,23). However, there are no studies showing that purified GRs bind specific germinants in vitro, which would be definitive proof that these proteins are indeed deserving of being called GRs.…”

Section: Overview Of Spore Germinationmentioning

confidence: 99%

Germination of Spores of Bacillus Species: What We Know and Do Not Know

2014

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Spores of Bacillus species can remain in their dormant and resistant states for years, but exposure to agents such as specific nutrients can cause spores' return to life within minutes in the process of germination. This process requires a number of sporespecific proteins, most of which are in or associated with the inner spore membrane (IM). These proteins include the (i) germinant receptors (GRs) that respond to nutrient germinants, (ii) GerD protein, which is essential for GR-dependent germination, (iii) SpoVA proteins that form a channel in spores' IM through which the spore core's huge depot of dipicolinic acid is released during germination, and (iv) cortex-lytic enzymes (CLEs) that degrade the large peptidoglycan cortex layer, allowing the spore core to take up much water and swell, thus completing spore germination. While much has been learned about nutrient germination, major questions remain unanswered, including the following. T he germination of the dormant and highly resistant spores formed by members of the Firmicutes phylum, in particular bacilli and clostridia, has long been of significant research interest for four major reasons, as follows: (i) fascinating regulatory systems allow such spores to remain in their dormant, resistant state for years and yet return to active growth in minutes; (ii) while spores of most Firmicutes do not cause disease, spores of some bacilli and clostridia cause food spoilage and food-borne disease, as well as human diseases like gas gangrene, tetanus, botulism, anthrax, and pseudomembranous colitis; (iii) spores of Bacillus anthracis are a major bioterrorism threat; and (iv) spores of Clostridium difficile are an emerging public health threat (1-3). Invariably, it is the germination of spores of these organisms that leads to disease or food spoilage, and yet, when spores germinate and lose their dormancy, they lose their extreme resistance properties and become relatively easy to kill. Germination is thus both an essential part of disease pathogenesis or food spoilage and a major weak spot in these organisms' life cycle. Consequently, there has long been applied interest in spore germination, with researchers seeking to understand this process better in order to either prevent spore germination or accelerate it and then kill the newly sensitive germinated spores. This review will concentrate on the germination of spores of bacilli, primarily because of the large amount of detailed knowledge of the germination of spores of these species compared to that of spores of clostridia. However, some of the differences and similarities between the germination of spores of these related genera will also be presented. Most discussion will focus on the germination of the model sporeformer, Bacillus subtilis, although the mechanisms of germination of B. subtilis spores appear to be similar for spores of other bacilli. The properties of the various proteins that are specifically involved in the germination process will not be discussed in great detail, since these have recently be...

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“…Both A-and B-type nGR subunits have been associated with germinant recognition (5,6,29,35). Site-directed mutagenesis of B-type nGR proteins in Bacillus subtilis and Bacillus megaterium has identified residues in the membrane-spanning regions of these proteins that are potentially involved in ligand binding (5,6). Both GerH A and GerH B contain membrane-spanning regions that could be available for interactions with nutrient germinants.…”

Section: Discussionmentioning

confidence: 99%

Membrane Topology of the Bacillus anthracis GerH Germinant Receptor Proteins

et al. 2012

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Bacillus anthracis spores are the etiologic agent of anthrax. Nutrient germinant receptors (nGRs) packaged within the inner membrane of the spore sense the presence of specific stimuli in the environment and trigger the process of germination, quickly returning the bacterium to the metabolically active, vegetative bacillus. This ability to sense the host environment and initiate germination is a required step in the infectious cycle. The nGRs are comprised of three subunits: the A-, B-, and C-type proteins. To date there are limited structural data for the A-and B-type nGR subunits. Here the transmembrane topologies of the B. anthracis GerH A , GerH B , and GerH C proteins are presented. C-terminal green fluorescent protein (GFP) fusions to various lengths of the GerH proteins were overexpressed in vegetative bacteria, and the subcellular locations of these GFP fusion sites were analyzed by flow cytometry and protease sensitivity. GFP fusion to full-length GerH C confirmed that the C terminus of this protein is extracellular, as predicted. GerH A and GerH B were both predicted to be integral membrane proteins by topology modeling. Analysis of C-terminal GFP fusions to full-length GerH B and nine truncated GerH B proteins supports either an 8-or 10-transmembrane-domain topology. For GerH A , C-terminal GFP fusions to full-length GerH A and six truncated GerH A proteins were consistent with a four-transmembrane-domain topology. Understanding the membrane topology of these proteins is an important step in determining potential ligand binding and protein-protein interaction domains, as well as providing new information for interpreting previous genetic work.

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Identification of a Receptor Subunit and Putative Ligand-Binding Residues Involved in the Bacillus megaterium QM B1551 Spore Germination Response to Glucose

Cited by 32 publications

References 48 publications

Genome Sequences of the Biotechnologically Important Bacillus megaterium Strains QM B1551 and DSM319

Genome Sequences of the Biotechnologically Important Bacillus megaterium Strains QM B1551 and DSM319

Germination of Spores of Bacillus Species: What We Know and Do Not Know

Membrane Topology of the Bacillus anthracis GerH Germinant Receptor Proteins

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