The arcABC gene cluster encoding the arginine deiminase pathway of Oenococcus oeni, and arginine induction of a CRP-like gene

Oenococcus oeni, the main species which induces malolactic fermentation in wine, uses arginine via the arginine deiminase (ADI) pathway. Using degener ated primers, two specific probes, one for ornithine transcarbamoylase (OTC ) and the other for carbamate kinase (CK), were synthesized. These made it possible to clone and sequence a cluster containing genes encoding ADI (arc A), OTC (arcB) and CK (arcC). In addition, sequence analysis upstream of th e arcA gene revealed the presence of an open reading frame (orf229) whose 3 '-end was only 101 bp-distant from the start codon of the arcA gene and sho wed similarity with members of the FNR (regulation for fumarate and nitrate reduction) and CRP (cAMP receptor protein) family of transcriptional regul ators. Moreover, a putative binding site for such regulators lies in the pr omoter region of the arcA gene. Induction of the arc cluster by arginine wa s studied first at the enzymatic level. The activities of the three enzymes strongly increased when cells were grown in the presence of the amino acid . In addition, the influence of arginine on gene transcription was monitore d by RT-PCR (reverse transcriptase-polymerase chain reaction). Expression o f the three arc genes, and particularly that of arcA, was positively affect ed by arginine supplementation and thus confirmed the enzymatic results. Mo reover, transcription of the putative CRP-like gene orf229 was also stimula ted by arginine. These data suggest that the protein encoded by orf229 coul d be a CRP-like regulator involved in the metabolism of O. oeni. (C) 2001 E ditions scientifiques et medicales Elsevier SAS.