Aldawood Esraa, Roberts Ian S
School of Biological Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom.
Clinical Laboratory Science, Collage of Applied Medical Science, King Saud University, Riyadh, Saudi Arabia.
Front Microbiol. 2022 Mar 10;13:858767. doi: 10.3389/fmicb.2022.858767. eCollection 2022.
The expression of a group 2 capsule (K antigen), such as the K1 or K5 antigen, is a key virulence factor of responsible for extra-intestinal infections. Capsule expression confers resistance to innate host defenses and plays a critical role in invasive disease. Capsule expression is temperature-dependent being expressed at 37°C but not at 20°C when outside the host. Group 2 capsule gene expression involves two convergent promoters PR1 and PR3, the regulation of which is critical to capsule expression. Temperature-dependent expression is controlled at transcriptional level directly by the binding of H-NS to PR1 and PR3 and indirectly through BipA with additional input from IHF and SlyA. More recently, other regulatory proteins, FNR, Fur, IHF, MprA, and LrhA, have been implicated in regulating capsule gene expression in response to other environmental stimuli and there is merging data for the growth phase-dependent regulation of the PR1 and PR3 promoters. The aim of the present Mini Review is to provide a unified update on the latest data on how the expression of group 2 capsules is regulated in response to a number of stimuli and the growth phase something that has not to date been addressed.
2型荚膜（K抗原）的表达，如K1或K5抗原，是引起肠外感染的关键毒力因子。荚膜表达赋予对宿主固有防御的抗性，并在侵袭性疾病中起关键作用。荚膜表达是温度依赖性的，在宿主体外时于37°C表达但在20°C时不表达。2型荚膜基因表达涉及两个收敛启动子PR1和PR3，其调控对荚膜表达至关重要。温度依赖性表达在转录水平直接由H-NS与PR1和PR3的结合控制，并通过BipA间接控制，同时还有来自IHF和SlyA的额外输入。最近，其他调节蛋白FNR、Fur、IHF、MprA和LrhA也参与响应其他环境刺激调节荚膜基因表达，并且有关于PR1和PR3启动子生长阶段依赖性调节的合并数据。本小型综述的目的是提供关于2型荚膜表达如何响应多种刺激和生长阶段进行调控的最新数据的统一更新，这是迄今为止尚未解决的问题。
