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

Abstract

Examination of the lipid composition of spore membranes of Bacillus subtilis Marburg, extracted after treatment of spores with dithiothreitol/urea and NaOH followed by lysozyme digestion, revealed that the spore membranes had significantly higher cardiolipin (CL) content than the membranes of exponentially growing cells. Analysis of the membranes of coat-defective, cotE :: cat and gerE :: cat mutant spores, which are susceptible to lysozyme digestion without chemical treatment, confirmed that spore membranes contain a high level of CL. After addition of the germinants L -alanine or AGFK (a combination of asparagine, glucose, fructose, and KCl), the turbidity of wild type spore suspensions decreased to 50% within 30 min. Suspensions of spores with only trace amounts of CL, however, showed no decrease in turbidity when L -alanine was added and the initial decrease in turbidity with AGFK was slight (14% after 60 min). These results indicate that CL is involved in an early step of germination, related to the functioning of germinant receptors. This is the first conspicuous in vivo evidence that CL in bacterial membranes has a specific role, in which it cannot be replaced by other anionic phospholipids.

Characterization and subcellular localization of a bacterial flotillin homologue

“…Therefore, we decided to analyse the distribution of YuaG-CFP during sporulation. It was described previously that almost all CL is localized to the prespore membrane in sporulating bacilli (Kawai et al, 2006). We found that sporulating cells that were stained with NAO exhibited a strong fluorescence at the prespore membrane (Fig.…”

“…However, the B. subtilis membrane is devoid of these lipids. Previous reports demonstrated the existence of CL microdomains in B. subtilis membranes (Kawai et al, 2004(Kawai et al, , 2006Matsumoto et al, 2006). Distribution of the CL domains in B. subtilis membranes was described as polar-or septal-localized; however, CL patches also formed foci (Kawai et al, 2004).…”

Selective Sorting of Cargo Proteins into Bacterial Membrane Vesicles

“…It has been proposed that microdomains, enriched in certain types of lipids and proteins, perform a localized activity during cell division and sporulation (40). For example, the phospholipid phosphatidylethanolamine is localized to the membranes of the polar septum during cell division and to the engulfment and forespore membranes at different sporulation stages (41). Likewise, cardiolipin is enriched in the spores (41,42).…”

“…For example, the phospholipid phosphatidylethanolamine is localized to the membranes of the polar septum during cell division and to the engulfment and forespore membranes at different sporulation stages (41). Likewise, cardiolipin is enriched in the spores (41,42). Theoretically, OM domains could be created by the formation of patches of different LPS molecules sorted according to polysaccharide composition or length.…”

FisB mediates membrane fission during sporulation in Bacillus subtilis

“…Cells lacking all three genes are viable and have undetectable levels of CL during vegetative growth (Kawai et al 2004). However, CL is readily detectable in the triple mutant during the early stages of sporulation, indicating that an additional sporulation-specific CL synthase exists or that CL is produced as a side reaction by a lipid synthesis/modification enzyme (Kawai et al 2004(Kawai et al , 2006Tan et al 2012). In accordance with the presence of CL during engulfment in cells lacking ClsA, ClsB, and YwiE, we found that the triple mutant was able to undergo fission at a frequency comparable with wild type (data not shown).…”