The sspB and sspE genes code for major small, acid-soluble proteins of Bacillus subtilis spores and are transcribed during sporulation by RNA polymerase containing sigma-G. Analysis of the expression in vivo and the sigma-G-dependent transcription in vitro of sspB and sspE genes carrying upstream deletions or point mutations in -10 and -35 promoter regions is consistent with sigma-G being the only major transcriptional regulator of these genes. These data also provide information on the residues in -10 and -35 regions which are most important for sigma-G recognition.