Proline biosynthesis encoded by the noc and occ loci of Agrobacterium Ti plasmids.

Octopine or nopaline Ti plasmids, or clones encoding their occ or noc loci, allowed proline auxotrophs of Agrobacterium tumefaciens to utilize the appropriate arginyl opine as a proline substitute. Arginine and ornithine substituted for proline only if the occ or noc loci were induced or made constitutive by mutation. These results support a report demonstrating a Ti plasmid-encoded activity in A. tumefaciens which cyclizes ornithine to proline.