Analysis of the regulation and function of five genes encoding small, acid-soluble spore proteins of Bacillus subtilis

Four genes [sspI sspK, sspM, and sspO (originally called cotK)] encoding mi nor small, acid-soluble proteins (SASP) unique to spores of Bacillus subtil is are expressed only in the forespore compartment of sporulating cells of this organism. The sspI sspK and sspM genes are monocistronic, while sspO i s the first gene in a likely operon with sspP (originally called cotL), whi ch also encodes a putative very small protein. Transcription of these genes is primarily, if not exclusively, by RNA polymerase with the forespore-spe cific sigma factor, sigma(G). Sequences centered 10 and 35 nt upstream of t he 5'-ends of sspI, sspK, sspM and sspO also show homology to the -10 and - 35 sequences recognized by sigma(G). Mutations deleting these genes cause t he loss of the appropriate SASP from spores, and the sspK sspM and sspO (an d likely sspP) mutations had no discernable effect on sporulation, spore pr operties or spore germination. Loss of sspI also had no effect on sporulati on, spore properties or spore germination, but Delta sspI spores had a sign ificant defect in spore outgrowth. (C) 2000 Elsevier Science B.V. All right s reserved.