Genetic characterization of the opp operon of Oenococcus oeni

The opp operon of O. oeni ML34, encoding the oligopeptide transport system, was cloned and genetically characterized. The operon consists of six genes and by sequence analysis, it is concluded that they encode an ABC (A&barbelow;TP B&barbelow;inding C&barbelow;assette) type of transporter. Two genes, oppA1 and oppA2, encode for putative substrate binding proteins. They are adjacently located and transcribed by individual promoters, although regulation of transcription of the oppA2 gene by the promoter located upstream of oppA1 cannot be excluded. Genes oppB, oppC, oppD and oppF encode for putative membrane associated proteins. Combining the oppA gene of L. lactis with genes oppBCDF of O. oeni, an opp L. lactis mutant transported a pentapeptide. A survey of nine oenococcal strains obtained from diverse origins indicates that the organization of the oppBCDF genes is conserved. However, variation was observed when oppA was considered. Restriction enzyme analysis and partial sequencing suggests that the strains tested can be divided into three groups. Interestingly, one group is characterized by the presence of only one copy of a gene encoding a substrate binding protein. Expression analysis in three oenococcal strains indicates that in the presence of a rich nitrogen source the opp genes are not expressed. In addition, expression of the opp genes in defined media can be correlated with increased cell yield if peptides are present. The host range of the lactococcal conjugal element pRS01 was determined. In addition, mobilization by pRS01 from Lactococcus lactis into several lactic acid bacteria was tested. Additional vectors that can be mobilized by pRS01 were also constructed.