Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada.
J Bacteriol. 2011 Jan;193(1):163-76. doi: 10.1128/JB.00852-10. Epub 2010 Oct 22.
Burkholderia cenocepacia is a significant opportunistic pathogen in individuals with cystic fibrosis. ShvR, a LysR-type transcriptional regulator, has previously been shown to influence colony morphology, biofilm formation, virulence in plant and animal infection models, and some quorum-sensing-dependent phenotypes. In the present study, it was shown that ShvR negatively regulates its own expression, as is typical for LysR-type regulators. The production of quorum-sensing signal molecules was detected earlier in growth in the shvR mutant than in the wild type, and ShvR repressed expression of the quorum-sensing regulatory genes cepIR and cciIR. Microarray analysis and transcriptional fusions revealed that ShvR regulated over 1,000 genes, including the zinc metalloproteases zmpA and zmpB. The shvR mutant displayed increased gene expression of the type II secretion system and significantly increased protease and lipase activities. Both ShvR and CepR influence expression of a 24-kb genomic region adjacent to shvR that includes the afcA and afcC operons, required for the production of an antifungal agent; however, the reduction in expression was substantially greater in the shvR mutant than in the cepR mutant. Only the shvR mutation resulted in reduced antifungal activity against Rhizoctonia solani. ShvR, but not CepR, was shown to directly regulate expression of the afcA and afcC promoters. In summary, ShvR was determined to have a significant influence on the expression of quorum-sensing, protease, lipase, type II secretion, and afc genes.
洋葱伯克霍尔德菌是囊性纤维化患者中一种重要的机会性病原体。ShvR 是一种 LysR 型转录调节因子，先前已被证明会影响菌落形态、生物膜形成、植物和动物感染模型中的毒力以及一些群体感应依赖的表型。在本研究中，表明 ShvR 负调控自身表达，这是 LysR 型调节剂的典型特征。ShvR 突变体中的群体感应信号分子的产生比野生型更早被检测到，并且 ShvR 抑制了群体感应调节基因 cepIR 和 cciIR 的表达。微阵列分析和转录融合表明，ShvR 调控了超过 1000 个基因，包括锌金属蛋白酶 zmpA 和 zmpB。ShvR 突变体显示出 II 型分泌系统的基因表达增加，并且显著增加了蛋白酶和脂肪酶活性。ShvR 和 CepR 都影响紧邻 shvR 的 24kb 基因组区域的表达，该区域包括 afcA 和 afcC 操纵子，这些基因是产生抗真菌剂所必需的；然而，在 shvR 突变体中表达的减少要比在 cepR 突变体中大得多。只有 shvR 突变导致对腐霉的抗真菌活性降低。ShvR，但不是 CepR，被证明直接调节 afcA 和 afcC 启动子的表达。总之，ShvR 对群体感应、蛋白酶、脂肪酶、II 型分泌和 afc 基因的表达有显著影响。
