EfficientvirGene Induction inAgrobacterium tumefaciensRequiresvirA,virG,andvirBox from the Same Ti Plasmid

• DOI: 10.1128/jb.183.13.4079-4089.2001
• Publication Date: 2002-07-27T10:01:09Z
• Authors: Atmakuri Krishnam...; V. Balaji; K. Veluthambi
• Keywords: Nicotiana; Transcriptional Activation; 0301 basic medicine; 0303 health sciences; Virulence Factors; Gene Expression Regulation, Bacterial; Regulatory Sequences, Nucleic Acid; Arginine; DNA-Binding Proteins; Plants, Toxic; 03 medical and health sciences; Bacterial Proteins; Agrobacterium tumefaciens; Genes, Bacterial; Plasmids; Transcription Factors

ABSTRACTThevirgenes of octopine, nopaline, andl,l-succinamopine Ti plasmids exhibit structural and functional similarities. However, we observed differences in the interactions between octopine and nopalinevircomponents. The induction of an octopinevirEA6::lacZfusion (pSM358cd) was 2.3-fold higher in an octopine strain (A348) than in a nopaline strain (C58). Supplementation of the octopinevirGA6in a nopaline strain with pSM358 did not completely restorevirEA6induction. However, addition of the octopinevirAA6to the above strain increasedvirEA6induction to a level almost comparable to that in octopine strains. In a reciprocal analysis, the induction of a nopalinevirEC58::catfusion (pUCD1553) was two- to threefold higher in nopaline (C58 and T37) strains than in octopine (A348 and Ach5) andl,l-succinamopine (A281) strains. Supplementation of nopalinevirAC58andvirGC58in an octopine strain (A348) harboring pUCD1553 increased induction levels ofvirEC58::catfusion to a level comparable to that in a nopaline strain (C58). Our results suggest that octopine andl,l-succinamopine VirG proteins induce the octopinevirEA6more efficiently than they do the nopalinevirEC58. Conversely, the nopaline VirG protein induces the nopalinevirEC58more efficiently than it does the octopinevirEA6. The ability of Bo542virGto bring about supervirulence in tobacco is observed for an octopinevirhelper (LBA4404) but not for a nopalinevirhelper (PMP90). Our analyses reveal that quantitative differences exist in the interactions between VirG andvirboxes of different Ti plasmids. Efficientvirgene induction in octopine and nopaline strains requiresvirA,virG,andvirboxes from the respective Ti plasmids.