title: Molecular characterization of the genes involved in the secretion and immunity of lactococcin Q, a two-peptide bacteriocin produced by Lactococcus lactis QU 4.
abstract: Lactococcin Q is a two-peptide (Qα and Qβ) bacteriocin produced by Lactococcus lactis QU 4, which exhibits specific antimicrobial activity against L. lactis strains. The lactococcin Q gene cluster (approximately 4.5 kb) was sequenced and found to include genes encoding lactococcin Q immunity (laqC), an ATP-binding cassette transporter (laqD) and a transport accessory protein (laqE), downstream of the lactococcin Q structural genes (laqA and laqB). In addition, the gene cluster showed high sequence identity with that of a lactococcin Q homologue bacteriocin, lactococcin G. Heterologous expression studies showed that LaqD was responsible for lactococcin Q secretion in a manner dependent on LaqE expression, and that LaqC conferred self-immunity to lactococcin Q and cross-immunity to lactococcin G. Amino acid alignment of both lactococcin transporters revealed that LaqD contains an insertion (160-168 residues) that is essential for lactococcin Q secretion, as L. lactis cells that expressed LaqDΔ160-168 were devoid of this function. Additional experiments demonstrated that the LaqDΔ160-168 mutant was, however, able to secrete lactococcin G, suggesting that the insertion is necessary only for the lactococcin Q secretion by LaqD. This report demonstrates the biosynthetic mechanism of lactococcin Q/G-type bacteriocins and the complementarity of the genes responsible for the secretion of lactococcins Q and G.
authors: 1​Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan.
authors: Naoki
authors: N
authors: Ishibashi
authors: 1​Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan.
authors: Takeshi
authors: T
authors: Zendo
authors: 1​Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan.
authors: Shoko
authors: S
authors: Koga
authors: 2​Health Research Institute, National Institute of Advanced Industrial Science and Technology, Osaka, Japan.
authors: Yasushi
authors: Y
authors: Shigeri
authors: 1​Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan 3​Department of Functional Metabolic Design, Bio-Architecture Center, Kyushu University, Fukuoka, Japan.
authors: Kenji
authors: K
authors: Sonomoto
mesh_terms: D001430:Bacteriocins / Q000235:genetics* / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005798:Genes, Bacterial; D013294:Lactococcus lactis / Q000235:genetics* / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
chemical_list: D001430:Bacteriocins; D004269:DNA, Bacterial; D026901:Membrane Transport Proteins; C069325:lactococcin A