Possible promoter regions within the proteolytic system in Streptococcus thermophilus and their interaction with the CodY homolog.

Possible promoter regions preceding 14 genes belonging to the proteolytic system of Streptococcus thermophilus KLDS 3.0503 were predicted by a promoter analysis softwarennpp. The 14 genes included an extracellular protease gene prtS, an oligopeptide ABC transport system gene amiA1, and 12 genes, respectively, encoding peptidases pepA, pepS, pepN, pepC, pepB, pepQ, pepV, pepT, pepM, pepXP, pepP, and pepO. These predicted promoter sequences were cloned and inserted into the upstream of a promoterless Escherichia coli gusA (β-glucuronidase) gene in a promoter probe vector pNZ273. The resulting vectors were, respectively, introduced into S. thermophilus KLDS 3.0503 and all 14 predicted promoter sequences were able to drive gusA expression, which indicated that these sequences were functional promoters. These promoters were able to interact with the S. thermophilus CodY homolog in an in vitro DNA binding assay but they did not contain a conserved CodY-box sequence identified in Lactococcus lactis. These results were useful for further studies on the regulation of protein metabolism in S. thermophilus. [ABSTRACT FROM AUTHOR]