Molecular characterization of Oenococcus ni genes encoding proteins involved in arginine transport

This work was carried out to complete the sequence of the arc cluster involved in arginine catabolism in Oenococcus ni, and particularly to characterize the genes encoding proteins involved in arginine transport. Using molecular cloning, two loci encoding proteins involved in the arginine-ornithine antiport were isolated. Their expression patterns were monitored by RT-PCR to study the influence of arginine on their transcription. Polycistronic mRNAs were detected. PCR performed directly on colonies with primer pairs specific of arc genes was used to discriminate strains able /unable to degrade arginine. Oenococcus ni contains two arcD loci encoding similar proteins. Their expression is not influenced by arginine and polycistronic messengers were detected. The inability to use arginine is due to a lack of genetic information encoding proteins of the arginine deiminase pathway. The constitutive expression of arcD genes points to the positive role of arginine on O. ni cell growth. The occasional presence of all the arc ABCD genes together in O. ni strains might provide insights into the growth rate variability within this species.