SummaryCatabolite repression of Bacillus subfilis catabolic operons is supposed to occur via a negative regulatory mechanism involving the recognition of a cis-acting catabolite-responsive element (cre) by a complex of &PA, which is a member of the GalR-Lac1 family of bacterial regulatory proteins, and the seryl-phosphorylated form of HPr (P-ser-HPr), as verified by recent studies on catabolite repression of the gnt operon. Analysis of the gnf promoter region by deletions and point mutations revealed that in addition to the cre in the first gene (gnfR) of the gnf operon (medown), this operon contains another cre located in the promoter region (we,,,). A translational gntR'-'lacZ fusion expressed under the control of various combinations of wild-type and mutant credown and cre,, was integrated into the chromosomal amyE locus, and then catabolite repression of p-galactosidase synthesis in the resultant integrants was examined. The in vivo results implied that catabolite repression exerted by cre,, was probably independent of catabolite repression exerted by cr%,,,; both cre,, and medown catabolite repression involved CcpA. Catabolite repression exerted by cre,, was independent of P-ser-HPr, and catabolite repression exerted by medown was partially independent of Pser-HPr. DNase I footprinting experiments indicated that a complex of CcpA and P-ser-HPr did not recognize cre,,, in contrast to its specific recognition of medown. However, CcpA complexed with glucose-6-phosphate specifically recognized cre,, as well as medown, but the physiological significance of this complexing is unknown.