CLONING AND CHARACTERIZATION OF THE GAMMA-GLUTAMYL PHOSPHATE REDUCTASE GENE OF CAMPYLOBACTER-JEJUNI

The gamma-glutamyl phosphate reductase gene, proA, of Campylobacter jejuni was isolated from a recombinant pBR322 clone. A HindIII fragment of the insert containing the gene was subcloned into pUC19 and sequenced in both orientations. The deduced amino acid sequence of gamma-glutamyl phosphate reductase (EC 1.2.1.41) of C.jejuni exhibits 36.4% identity to that of Escherichia coli and 36.0% identity to Serratia marcescens. Two highly conserved regions in the amino acid sequence were identified from the alignment of the three available gamma-glutamyl phosphate reductase gene sequences. The gene was expressed from its own promoter and the transcription start site was mapped. The proline biosynthetic genes of C. jejuni are not located tandemly and thus differ in this respect from those of E. coli and S. marcescens, where gamma-glutamyl phosphate reductase and gamma-glutamyl kinase (proB) are located in a single operon.