Heiskanen P, Taira S, Rhen M
Department of Biochemistry, University of Helsinki, Finland.
FEMS Microbiol Lett. 1994 Oct 15;123(1-2):125-30. doi: 10.1111/j.1574-6968.1994.tb07211.x.
Salmonella plasmid virulence (spv) genes are organized into two transcriptional units: one formed by the spvR gene and the other by the spvA, spvB, spvC and spvD genes. Transcription of both units is activated by SpvR, a regulatory protein of the LysR family. The effect of RpoS, a stationary phase-associated sigma factor, on the expression of spv genes was studied using lacZ transcriptional fusions to spvR and spvA in wild-type and rpoS Escherichia coli backgrounds. Mutant and wild-type SpvR proteins were expressed in trans from a multicopy plasmid. The results show that the combined action of rpoS and spvR is necessary for transcription of spvA and that this combination also enhances transcription of spvR. Interestingly, spvR can also be transcribed in an alternative manner, i.e. in the absence of rpoS or spvR or both. The possible role for SpvR as a repressor of its own transcription is discussed.
沙门氏菌质粒毒力（spv）基因被组织成两个转录单元：一个由spvR基因形成，另一个由spvA、spvB、spvC和spvD基因形成。两个单元的转录均由LysR家族的调节蛋白SpvR激活。利用在野生型和rpoS大肠杆菌背景下与spvR和spvA的lacZ转录融合，研究了与稳定期相关的σ因子RpoS对spv基因表达的影响。突变型和野生型SpvR蛋白从多拷贝质粒中反式表达。结果表明，rpoS和spvR的共同作用对于spvA的转录是必需的，并且这种组合还增强了spvR的转录。有趣的是，spvR也可以以另一种方式转录，即在没有rpoS或spvR或两者都没有的情况下。讨论了SpvR作为其自身转录阻遏物的可能作用。
