Promoters ofAgrobacterium tumefaciensTi-plasmid virulence genes

Abstract

The DNA sequences of the promoter and 5′ upstream regions of six Aqrobacterium tumefaciens Ti-plasmid encoded virulence ( vir ) genes were determined. The transcription initiation sites were mapped by the S ₁ nuclease protection assay. In the −10 region, the vir promoters share a consensus sequence that is homologous to a DNA sequence found in the same region of E. coli promoters. In contrast, the −35 region sequences are variable. Several vir genes contain two common hexanucleotide sequences, 5′CGAGTA3′ and 5′GCAATT3′. Translation initiation codons for all vir genes, except virG , are preceded by sequences homologous to the ribosome binding site sequences found in E. coli .