The N-terminal domain of VirG of Agrobacterium tumefadens: modelling and analysis of mutant phenotypes

Fourteen mutants in the N-terminal domain of virulence factorG (VirG) were obtained by random mutagenesis. Two mutants showedan altered phenotype, all others were nonfunctional.All mutantscan still be phosphorylated and bind to DNA. A 3-D model wasbuilt based on the coordinates of chemotaxis protein Y (CheY).Many of the observed phenotypic changes of VirG are explainedqualitatively. Combination of model building and biochemicalinformation leads to the conclusion that the active sites ofVirG and CheY must partly use different residues to performthe same phosphorylation and dephosphorylation reactions.