Genetic Analysis of a Unique Bacteriocin, Smb, Produced by Streptococcus mutans GS5

• DOI: 10.1128/aac.49.2.541-548.2005
• Publication Date: 2005-01-26T22:04:40Z
• Authors: Hideo Yonezawa; Howard K. Kuramitsu
• Keywords: Lantibiotics

A dipeptide lantibiotic, named Smb, in Streptococcus mutans GS5 was characterized by molecular genetic approaches. The Smb biosynthesis gene locus is encoded a 9.5-kb region of chromosomal DNA and consists seven genes the order smbM1, -T, -F, -M2, -G, -A, -B. This operon not present some other strains S. mutans, including strain UA159. encoding were identified as smbA smbB. Inactivation smbA, or smbB attenuated inhibition growth indicator RP66, confirming an essential role for these expression. Mature likely 30-amino-acid SmbA together with 32-amino-acid SmbB. exhibited similarity mature lantibiotic lacticinA2 from Lactococcus lactis, while SmbB similar to mersacidin-like peptides Bacillus halodurans L. lactis. We also demonstrated that expression induced competence-stimulating peptide (CSP) com box-like sequence located smb promoter region. These results suggest belongs class I bacteriocin family, its dependent on CSP-induced quorum sensing.