J. von Lintig

Functional Organization of the Regions Responsible for Nopaline and Octopine Catabolism in Ti Plasmids of Agrobacterium Tumefaciens

The catabolism of opines synthesized in transformed plant cells by Agrobacterium is an important aspect in the bacteria/plant interaction. We investigate Ti plasmid genes in the noc-region of pTiC58 and in the occ-region of pTiAch5 which are necessary for catabolism of nopaline and octopine, respectively. Results with a binary vector system indicate that both regions code for constitutively expressed proteins which are necessary and sufficient for activation in trans of the catabolic functions in presence of the opines. These proteins from the noc- and the occ-region reveal significant similarities to each other and to regulatory proteins characterized in other bacteria. The positions of the inducible promoters have been mapped to regions of less than 0.5 kbp. Apart from proteins directly involved in opine catabolism, both regions code for at least two proteins which are related to transport proteins in other bacteria. These and previous results indicate that several genes in the noc- and the occ-region are related, but adapted for function in nopaline and octopine utilization.