Luo Mei, Yang Shiya, Li Xuan, Liu Pin, Xue Jian, Zhou Xipeng, Su Kewen, Xu Xuan, Qing Ying, Qiu Jingfu, Li Yingli
School of Public Health and Management, Chongqing Medical University, Chongqing, China.
Dianjiang center for disease control and prevention, Chongqing, China.
PLoS One. 2017 Jul 21;12(7):e0180666. doi: 10.1371/journal.pone.0180666. eCollection 2017.
Klebsiella pneumoniae (K. pneumoniae) is an opportunistic pathogen that can adhere to host cells or extracellular matrix via type 1 and type 3 fimbriae. KP1_4563 is a gene encoding a hypothetical protein in K. pneumoniae NTUH-K2044. KP1_4563 is located between the type 1 and type 3 fimbrial gene clusters and is likely associated with fimbrial function given its putative conserved domains of unknown function (DUF1471). Cyclic AMP receptor protein (CRP) regulates virulence-related gene expression and is a crucial transcriptional regulator in many bacteria. The predicted DNA recognition motif of CRP is present in the KP1_4563 promoter region. This study aimed to investigate the function of KP1_4563 in fimbriae and its transcriptional regulation mechanism by CRP. We generated Kp-Δ4563 mutant and complementation strains. We utilized phenotype and adhesion assays to evaluate the role of KP1_4563 in fimbriae. We conducted quantitative RT-PCR (qRT-PCR), LacZ fusion, electrophoretic mobility shift, and DNase I footprinting assays to study the transcriptional regulation of KP1_4563 gene by CRP. We found that KP1_4563 negatively regulates the function of type 3 fimbriae. Compared with NTUH-K2044, the absence of KP1_4563 enhanced the ability of Kp-Δ4563 to adhere to A549 cells. CRP negatively regulates KP1_4563 by directly binding to its promoter region. KP1_4563 plays an important role in type 3 fimbrial function. This novel insight will assist in the development of strategies for preventing K. pneumoniae infection.
肺炎克雷伯菌是一种机会致病菌，可通过1型和3型菌毛黏附于宿主细胞或细胞外基质。KP1_4563是肺炎克雷伯菌NTUH-K2044中一个编码假定蛋白的基因。KP1_4563位于1型和3型菌毛基因簇之间，鉴于其具有功能未知的假定保守结构域（DUF1471），可能与菌毛功能相关。环磷酸腺苷受体蛋白（CRP）调节毒力相关基因的表达，是许多细菌中关键的转录调节因子。CRP的预测DNA识别基序存在于KP1_4563启动子区域。本研究旨在探究KP1_4563在菌毛中的功能及其受CRP的转录调控机制。我们构建了Kp-Δ4563突变体和互补菌株。我们利用表型和黏附试验评估KP1_4563在菌毛中的作用。我们进行了定量逆转录聚合酶链反应（qRT-PCR）、LacZ融合、电泳迁移率变动分析和DNase I足迹试验，以研究CRP对KP1_4563基因的转录调控。我们发现KP1_4563对3型菌毛的功能起负调节作用。与NTUH-K2044相比，KP1_4563缺失增强了Kp-Δ4563黏附A549细胞的能力。CRP通过直接结合其启动子区域对KP1_4563起负调节作用。KP1_4563在3型菌毛功能中起重要作用。这一新见解将有助于制定预防肺炎克雷伯菌感染的策略。
