THE N-TERMINAL DOMAIN OF VIRG OF AGROBACTERIUM-TUMEFACIENS - MODELINGAND ANALYSIS OF MUTANT PHENOTYPES

Fourteen mutants in the N-terminal domain of virulence factor G (VirG) were obtained by random mutagenesis. Two mutants showed an altered ph enotype, all others were nonfunctional. All mutants can still be phosp horylated and bind to DNA. A 3-D model was built based on the coordina tes of chemotaxis protein Y (CheY). Many of the observed phenotypic ch anges of VirG are explained qualitatively. Combination of model buildi ng and biochemical information leads to the conclusion that the active sites of VirG and CheY must partly use different residues to perform the same phosphorylation and dephosphorylation reactions.