Aoyama T, Takanami M, Oka A
Institute for Chemical Research, Kyoto University, Japan.
Nucleic Acids Symp Ser. 1989(21):17-8.
VirG protein is known to be the positive regulator for vir genes of Ri and Ti plasmids in Agrobacterium. To investigate the cis-acting element recognized by VirG, we have determined the transcriptional start points of the vir genes on Ri plasmid (pRiA4b). From the analysis of the upstream sequences, it has been found that the sequences generally similar to 5'TG(A/T)AA(C/T)3' appear in phase with an 11-base pair interval, and that the -35 and -10 regions of the promoters are located nearly in the reversal phase with those phasing sequences. These sequence characteristics are conserved in the vir genes on Ti plasmids (pTiA6 and pTiC58). Moreover, the similar sequence structures were found in the regulatory regions of the genes controlled by PhoB and OmpR, which are the E. coli positive regulators closely related to VirG in their amino-acid sequences.
已知VirG蛋白是根癌土壤杆菌中Ri和Ti质粒的vir基因的正调控因子。为了研究VirG识别的顺式作用元件，我们确定了Ri质粒（pRiA4b）上vir基因的转录起始点。通过对上游序列的分析，发现通常与5'TG(A/T)AA(C/T)3'相似的序列以11个碱基对的间隔呈相位出现，并且启动子的-35和-10区域与那些相位序列几乎处于相反相位。这些序列特征在Ti质粒（pTiA6和pTiC58）上的vir基因中是保守的。此外，在由PhoB和OmpR控制的基因的调控区域中发现了相似的序列结构，PhoB和OmpR是在氨基酸序列上与VirG密切相关的大肠杆菌正调控因子。
