Characterization of the vir A gene of the agropine-type plasmid pRiA4 of Agrobacterium rhizogenes

Abstract

We sequenced a 4.2-kb DNA region encompassing the virA locus of the hairy-root-inducing plasmid pRiA4, and compared its sequence with the published virA region sequences of four tumor-inducing plasmids. An open reading frame capable of coding for 829 amino acids was identified for virA. Deletion mutants of virA constructed by fusing to lacZ, but not the wild-type gene itself, were efficiently expressed in Escherichia coli when they were put downstream front the lac promoter. These fused gene products became soluble or insoluble depending on the length of their lacZ moieties.