Nucleotide sequence and gene organization of the gerK spore germination locus of Bacillus subtilis 168.

Irie, Ryozaburo; Fujita, Yasuhito; Kobayashi, Miho

doi:10.2323/jgam.42.141

Cited by 15 publications

(16 citation statements)

References 23 publications

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“…In spores of Bacillus subtilis, there are three functional GRs (GerA, GerB, and GerK), the GerA GR responding to L-alanine or L-valine and the GerB and GerK GRs cooperatively responding to a mixture of L-asparagine, D-glucose, D-fructose, and K ϩ (AGFK) (8)(9)(10). Normally, L-asparagine alone does not trigger B. subtilis spore germination.…”

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confidence: 99%

Monitoring of Commitment, Blocking, and Continuation of Nutrient Germination of Individual Bacillus subtilis Spores

Zhang

Liang

et al. 2014

J Bacteriol

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bShort exposures of Bacillus spores to nutrient germinants can commit spores to germinate when germinants are removed or their binding to the spores' nutrient germinant receptors (GRs) is inhibited. Bacillus subtilis spores were exposed to germinants for various periods, followed by germinant removal to prevent further commitment. Release of spore dipicolinic acid (DPA) was then measured by differential interference contrast microscopy to monitor germination of multiple individual spores, and spores did not release DPA after 1 to 2 min of germinant exposure until ϳ7 min after germinant removal. With longer germinant exposures, percentages of committed spores with times for completion of DPA release (T release ) greater than the time of germinant removal (T b ) increased, while the time T lag ؊ T b , where T lag represents the time when rapid DPA release began, was decreased but rapid DPA release times (⌬T release ‫؍‬ T release ؊ T lag ) were increased; Factors affecting average T release values and the percentages of committed spores were germinant exposure time, germinant concentration, sporulation conditions, and spore heat activation, as previously shown for commitment of spore populations. Surprisingly, germination of spores given a 2nd short germinant exposure 30 to 45 min after a 1st exposure of the same duration was significantly higher than after the 1st exposure, but the number of spores that germinated in the 2nd germinant exposure decreased as the interval between germinant exposures increased up to 12 h. The latter results indicate that spores have some memory, albeit transient, of their previous exposure to nutrient germinants.

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confidence: 99%

Monitoring of Commitment, Blocking, and Continuation of Nutrient Germination of Individual Bacillus subtilis Spores

Zhang

Liang

et al. 2014

J Bacteriol

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“…In B. subtilis, germination can be induced by L-alanine or by a mixture of asparagine, glucose, fructose, and potassium ions. Receptors involved in sensing these environmental cues are GerA, GerB, and GerK (14,21). After the germinant is sensed, a large depot of calcium dipicolinate (Ca 2ϩ -DPA) is released, the core hydrates, the cortex is degraded, and metabolism begins (34).…”

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Bile Salts and Glycine as Cogerminants for Clostridium difficile Spores

2008

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Spore formation by Clostridium difficile is a significant obstacle to overcoming hospital-acquired C. difficileassociated disease. Spores are resistant to heat, radiation, chemicals, and antibiotics, making a contaminated environment difficult to clean. To cause disease, however, spores must germinate and grow out as vegetative cells. The germination of C. difficile spores has not been examined in detail. In an effort to understand the germination of C. difficile spores, we characterized the response of C. difficile spores to bile. We found that cholate derivatives and the amino acid glycine act as cogerminants. Deoxycholate, a metabolite of cholate produced by the normal intestinal flora, also induced germination of C. difficile spores but prevented the growth of vegetative C. difficile. A model of resistance to C. difficile colonization mediated by the normal bacterial flora is proposed.

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“…The best understood example of this is probably the B. subtilis germination response to a mixture of asparagine, glucose, fructose, and potassium ions, which requires both the GerB and GerK receptors (1,4,15). The response to single germinants can also require interaction between two or more receptors, such as the inosine germination response in Bacillus cereus 569, which has a strict requirement for the products of the gerI and gerQ operons (2).…”

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confidence: 99%

Role of Chromosomal and Plasmid-Borne Receptor Homologues in the Response of Bacillus megaterium QM B1551 Spores to Germinants

Christie

Lowe

2007

J Bacteriol

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Spores of Bacillus megaterium QM B1551 germinate in response to a number of trigger compounds, including glucose, proline, leucine, and inorganic salts. An approximate 6-kb region of the 165-kb plasmid was found to harbor a tricistronic receptor operon, gerU, and a monocistronic receptor component, gerVB. The gerU operon was observed to complement the germination response in plasmidless strain PV361 to glucose and leucine, with KBr acting as a cogerminant. Proline recognition is conferred by the monocistronic gerVB gene, the presence of which also improves the germination response to other single-trigger compounds. A chimeric receptor, GerU*, demonstrates interchangeability between receptor components and provides evidence that it is the B protein of the receptor that determines germinant specificity. Introduction of the gerU/gerVB gene cluster to B. megaterium KM extends the range of germinants recognized by this strain to include glucose, proline, and KBr in addition to alanine and leucine. A chromosomally encoded receptor, GerA, the B component of which is predicted to be truncated, was found to be functionally redundant. Similarly, the plasmid-borne antiporter gene, grmA, identified previously as being essential for germination in QM B1551, did not complement the germination defect in the plasmidless variant PV361. Wild-type spores carrying an insertion-deletion mutation in this cistron germinated normally; thus, the role of GrmA in spore germination needs to be reevaluated in this species.Bacterial spores rely upon a number of small molecules, including amino acids, purine ribosides, sugars, and ions, to indicate that environmental conditions are favorable for the resumption of growth. The rapid transition from extreme dormancy to loss of resistance properties and resumption of metabolism displayed by spores upon exposure to germinant molecules is regulated by a process known as spore germination (22,23,32). Germinant interaction with cognate receptors located within the inner spore membrane (11, 26) stimulates changes in the permeability of this membrane to various metal ions and Ca-dipicolinic acid (DPA), which are effluxed from the spore core, while permitting partial hydration of the spore core. Enzymatic hydrolysis of the spore's thick layer of cortical peptidoglycan and protective outer coat layers is then initiated, permitting complete hydration and the resumption of vegetative metabolism. Since strict germination events precede macromolecular synthesis, the germination apparatus must be present in the dormant spore (22,32).A substantial amount of genetic evidence has been presented that strongly suggests that orthologous proteins belonging to the GerA family form the receptors through which the spore senses its environment (21,23,25). GerA structural genes are arranged in tricistronic operons, which are expressed during sporulation in the developing forespore (7). Multiple copies of these receptor operons reside within the genomes of all Bacillus species examined to date. Hydropathy profiling indica...

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Nucleotide sequence and gene organization of the gerK spore germination locus of Bacillus subtilis 168.

Cited by 15 publications

References 23 publications

Monitoring of Commitment, Blocking, and Continuation of Nutrient Germination of Individual Bacillus subtilis Spores

Monitoring of Commitment, Blocking, and Continuation of Nutrient Germination of Individual Bacillus subtilis Spores

Bile Salts and Glycine as Cogerminants for Clostridium difficile Spores

Role of Chromosomal and Plasmid-Borne Receptor Homologues in the Response of Bacillus megaterium QM B1551 Spores to Germinants

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