Role of GerD in Germination of
            <i>Bacillus subtilis</i>
            Spores

Pelczar, Patricia L.; Igarashi, Tadashi; Setlow, Barbara; Setlow, Peter

doi:10.1128/jb.01606-06

Cited by 76 publications

(100 citation statements)

References 37 publications

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“…Loss of GerD increases the heterogeneity in nutrient-triggered spore germination, most likely by greatly increasing the lag time between the addition of nutrients and the initiation of Ca-DPA release (29). Although how GerD modulates the length of the lag time in nutrient germination is not known, GerD has no effects on spore germination with either Ca-DPA or dodecylamine, consistent with the normal germination of superdormant spores with these two agents.…”

Section: Vol 191 2009mentioning

confidence: 62%

“…At present, four such essential components for B. subtilis spore germination are known, as follows: (i) one or both of the redundant CLEs, CwlJ and SleB; (ii) the channels that allow DPA release in stage I of germination that may be composed of SpoVA proteins (28,38,39); (iii) the GerD protein that greatly stimulates Bacillus sp. spore germination with agents that target the germinant receptors (29,30); and (iv) the germinant receptors. It appears unlikely that the culprit is the CLEs, since superdormant spores germinated normally with exogenous Ca-DPA, and this agent triggers germination by activating CwlJ (36).…”

Section: Discussionmentioning

confidence: 99%

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Isolation and Characterization of Superdormant Spores of Bacillus Species

2009

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Superdormant spores of Bacillus subtilis and Bacillus megaterium were isolated in 4 to 12% yields following germination with high nutrient levels that activated one or two germinant receptors. These superdormant spores did not germinate with the initial nutrients or those that stimulated other germinant receptors, and the superdormant spores' defect was not genetic. The superdormant spores did, however, germinate with Ca 2؉ -dipicolinic acid or dodecylamine. Although these superdormant spores did not germinate with high levels of nutrients that activated one or two nutrient germinant receptors, they germinated with nutrient mixtures that activated more receptors, and using high levels of nutrient mixtures activating more germinant receptors decreased superdormant spore yields. The use of moderate nutrient levels to isolate superdormant spores increased their yields; the resultant spores germinated poorly with the initial moderate nutrient concentrations, but they germinated well with high nutrient concentrations. These findings suggest that the levels of superdormant spores in populations depend on the germination conditions used, with fewer superdormant spores isolated when better germination conditions are used. These findings further suggest that superdormant spores require an increased signal for triggering spore germination compared to most spores in populations. One factor determining whether a spore is superdormant is its level of germinant receptors, since spore populations with higher levels of germinant receptors yielded lower levels of superdormant spores. A second important factor may be heat activation of spore populations, since yields of superdormant spores from non-heat-activated spore populations were higher than those from optimally activated spores. Spores of variousBacillus species are formed in sporulation and are metabolically dormant and very resistant to environmental stress factors (21, 37). While such spores can remain in this dormant, resistant state for long periods, they can return to life rapidly through the process of germination, during which the spore's dormancy and extreme resistance are lost (36). Spore germination has long been of intrinsic interest, and continues to attract applied interest, because (i) spores of a number of Bacillus species are major agents of food spoilage and food-borne disease and (ii) spores of Bacillus anthracis are a major bioterrorism agent. Since spores are much easier to kill after they have germinated, it would be advantageous to trigger germination of spores in foods or the environment and then readily inactivate the much less resistant germinated spores. However, this simple strategy has been largely nullified because germination of spore populations is heterogeneous, with some spores, often called superdormant spores, germinating extremely slowly and potentially coming back to life long after treatments are applied to inactivate germinated spores (8,9,16). The concern over superdormant spores in populations also affects decisions such as how lon...

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Section: Vol 191 2009mentioning

confidence: 62%

Section: Discussionmentioning

confidence: 99%

Isolation and Characterization of Superdormant Spores of Bacillus Species

2009

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“…The GerD protein is also essential for rapid GR-dependent spore germination and for germinosome assembly, and this protein is also present in the spore's IM, where it is presumably anchored by a covalently attached diacylglycerol moiety that is also present in GR C subunits (9,12,13). Loss of this diacylglycerol anchor eliminates both GerD and GR C protein function, consistent with these proteins' inner membrane location, and almost certainly on the outer leaflet of the inner membrane (13,15,16). However, how GRs recognize specific nutrients, how nutrient recognition triggers the downstream events in spore germination, and how GerD influences GR function are largely unknown.…”

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confidence: 73%

Numbers of Individual Nutrient Germinant Receptors and Other Germination Proteins in Spores of Bacillus subtilis

Stewart

Setlow

2013

J Bacteriol

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-type spores were determined by Western blot analysis of spore fractions or total disrupted spores by comparison with known amounts of purified proteins. Surprisingly, after disruption of decoated B. subtilis spores with lysozyme and fractionation, ϳ90% of IM fatty acids and GR subunits remained with the spores' insoluble integument fraction, indicating that yields of purified IM are low. The total lysate from disrupted wild-type spores contained ϳ2,500 total GRs/spore: GerAA and GerAC subunits each at ϳ1,100 molecules/spore and GerBC and GerKA subunits each at ϳ700 molecules/spore. Levels of the GerBA subunit determined previously were also predicted to be ϳ700 molecules/spore. These results indicate that the A/C subunit stoichiometry in GRs is most likely 1:1, with GerA being the most abundant GR. GerD and SpoVAD levels were ϳ3,500 and ϳ6,500 molecules/spore, respectively. These values will be helpful in formulating mathematic models of spore germination kinetics as well as setting lower limits on the size of the GR-GerD complex in the spores' IM, termed the germinosome.

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“…While the GRs are essential for nutrient germination, the normal function of GRs requires the GerD protein (4,58). This small protein is also on the outer sur-face of the IM and is held there, at least in part, by a lipid anchor (54,59).…”

Section: Major Unanswered Questions About Spore Germination By Nutrientsmentioning

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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Role of GerD in Germination of Bacillus subtilis Spores

Cited by 76 publications

References 37 publications

Isolation and Characterization of Superdormant Spores of Bacillus Species

Isolation and Characterization of Superdormant Spores of Bacillus Species

Numbers of Individual Nutrient Germinant Receptors and Other Germination Proteins in Spores of Bacillus subtilis

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

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