Molecular characterization of the Lactococcus lactis ptsHI operon and analysis of the regulatory role of HPr

The molecular characterization of the Lactococcus lactis ptsHI operon and analysis of the regulatory role of HPr were conducted. The L. lactis ptsH and ptsI genes were cloned and a promoter sequence was identified upstream of the ptsHI operon. Results demonstrate the role of HPr(Ser-P) as corepressor in the catabolite repression of the gal operon. Findings also reveal that HPr(Ser-P) acts as a coactivator in the CcpA-mediated catabolite activation of the pyruvate kinase and L-lactate dehydrogenase genes.