Matthias Kathryn A, Rest Richard F
Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA, USA.
Mol Microbiol. 2014 Mar;91(6):1120-35. doi: 10.1111/mmi.12522. Epub 2014 Feb 13.
Contact-regulated gene A (CrgA) is a transcriptional regulator present in the pathogenic Neisseria that functions as both an activator and a repressor of transcription following contact with host cells. While its mechanism of action has been studied extensively in Neisseria meningitidis, the specific subset of genes that CrgA targets has been debated. Although the majority of these constitute virulence genes, suggesting that CrgA is important in pathogenesis, no study to date has examined the effects of CrgA in Neisseria gonorrhoeae. In this report, we generated a knockout mutant of crgA (ΔcrgA) in the serum-sensitive gonococcal strain F62. crgA deletion resulted in a reduction in the transcript and protein levels of the primary pilin component pilE via mechanisms that were both contact-dependent and -independent. In contrast, ΔcrgA overexpressed the main determinant of serum resistance in F62, lipooligosaccharide sialyltransferase (Lst). CrgA-mediated lst repression was direct as both recombinant and native CrgA bound to the lst promoter at multiple locations in EMSA and ChIP assays respectively. The increase in Lst levels associated with crgA deletion correlated with enhanced protection against killing by normal human serum. These data suggest a role for CrgA in virulence regulation during both cell adherence and planktonic growth.
接触调节基因A（CrgA）是一种存在于致病性奈瑟菌中的转录调节因子，在与宿主细胞接触后，它既作为转录激活因子又作为转录抑制因子发挥作用。虽然其作用机制已在脑膜炎奈瑟菌中得到广泛研究，但CrgA靶向的特定基因子集一直存在争议。尽管其中大多数构成毒力基因，这表明CrgA在发病机制中很重要，但迄今为止尚无研究考察CrgA在淋病奈瑟菌中的作用。在本报告中，我们在血清敏感的淋球菌菌株F62中构建了crgA基因敲除突变体（ΔcrgA）。crgA基因缺失导致主要菌毛成分pilE的转录水平和蛋白水平降低，其机制既有接触依赖性的，也有非接触依赖性的。相反，ΔcrgA使F62中血清抗性的主要决定因素脂寡糖唾液酸转移酶（Lst）过度表达。CrgA介导的lst抑制是直接的，因为在电泳迁移率变动分析（EMSA）和染色质免疫沉淀分析（ChIP）中，重组CrgA和天然CrgA分别在多个位点与lst启动子结合。与crgA基因缺失相关的Lst水平升高与抵抗正常人血清杀伤的能力增强相关。这些数据表明CrgA在细胞黏附和浮游生长过程中的毒力调节中发挥作用。
