Effects of a gerF ( lgt ) Mutation on the Germination of Spores of Bacillus subtilis

Abstract

One of the proteins of the membrane-bound receptors that recognize individual nutrients that trigger germination of spores of Bacillus subtilis contains the recognition sequence for diacylglycerol addition to a cysteine residue near the protein's N terminus. B. subtilis spores lacking the gerF (lgt) gene that codes for prelipoprotein diacylglycerol transferase exhibited significantly slowed germination in response to nutrient germinants as found previously, but germination of gerF spores with a mixture of Ca 2؉ and dipicolinic acid or with dodecylamine was normal, as was the spontaneous germination of gerF spores lacking all nutrient germinant receptors. The deleterious effects of the gerF mutation on nutrient germination were highest on germination triggered by the GerA nutrient receptor and were less so (but still significant) on germination triggered by the GerB nutrient receptor. However, there was little, if any, effect on GerK nutrient receptormediated spore germination. As predicted from the latter results, replacement by alanine of the cysteine residue to which diacylglycerol is thought to be added to these nutrient receptors had a large effect on GerA receptor function, less effect on GerB receptor function, and little, if any, effect on GerK receptor function.Spores of Bacillus species are metabolically dormant and can remain so for long periods. However, these dormant spores can rapidly return to vegetative growth via the processes of spore germination and then outgrowth (14,15,23). Spores normally initiate germination in response to nutrient germinants, such as amino acids and sugars. These nutrient germinants are sensed by receptors in the spore's inner membrane that interact with nutrients in a stereospecific manner, and this receptor-nutrient interaction triggers subsequent events in spore germination (5,14,15,16,22,23). There are three functional nutrient receptors in Bacillus subtilis spores, encoded by the homologous gerA, gerB, and gerK operons (termed gerA operon homologs), and gerA gerB gerK spores do not germinate in response to nutrients (14,15,16,20,21). The gerA operon homologs are tricistronic, and the three proteins (termed A, B, and C) encoded by each operon probably interact to form the functional nutrient receptor.

Cardiolipin Enrichment in Spore Membranes and Its Involvement in Germination of Bacillus subtilis Marburg

“…The AGFK receptor complex may be more deformation tolerant than the L -alanine receptor. This suggestion is supported by the observation that, similarly, the lack of prelipoprotein diacylglycerol transferase (GerF), which causes a defect in the lipid modification of the C component, completely eliminates the function of Lalanine receptor (GerA), which is presumed to be localized in the inner spore membranes (Hudson et al, 2001), but does only moderately and slightly, respectively, impair the function of the AGFK receptors, GerB and GerK (Igarashi et al, 2004).…”

“…On the other hand, DPA is released in large quantities after exposure to a cationic surfactant, dodecylamine, and spores lacking either of, or even all, the known nutrient receptors release DPA well with dodecylamine (Setlow et al, 2003). We were not able to measure the turbidity decrease in this case because dodecylamine induces clumping of spores and this affects turbidity significantly as described by Igarashi et al (2004). When the mutant spores with a trace amount of CL were exposed to dodecylamine, the DPA release was not repressed, but at a rate comparable to that of the wild type (Fig.…”

Cooperativity Between Different Nutrient Receptors in Germination of Spores of Bacillus subtilis and Reduction of This Cooperativity by Alterations in the GerB Receptor

“…4). Unfortunately, the structures of the nutrient receptors are not known, although the three proteins encoded by the operons encoding each nutrient receptor physically interact (11,12,17,20). Proteins of one receptor can also physically interact with those of a different nutrient receptor, although the degree of this interaction is not clear (12,30).…”

Lipoprotein biogenesis in Gram-positive bacteria: knowing when to hold ‘em, knowing when to fold ‘em

“…In addition to the sensing of peptides described earlier, lipoproteins have roles in cell envelope sensing processes, including the modulation of two-component signal transduction systems [44,69,70] and the Bacillus germinant receptors GerAC, GerBC, GerD and GerKC [46,71]. Moreover, genome analyses have consistently identified putative lipoproteins predicted to have important roles in cell envelope stability and cell wall cross-linking or remodelling such as penicillin binding proteins and peptidoglycan hydrolases [18,54].…”

“…Unsurprisingly, given the variety of functions attributable to lipoproteins, lgt or lsp mutations have pleiotropic effects. For example, lgt mutants of B. subtilis exhibit defects in cytochrome caa 3 activity [43], protein secretion [33], germination and sporulation [44][45][46] that can be correlated to impaired functions of specific lipoproteins.…”