Plasticity of Regulation of Mannitol Phosphotransferase System Operon by CRP-cAMP Complex in Vibrio cholerae

Objective The complex of the cyclic AMP receptor protein （CRP） and cAMP is an important transcriptional regulator of numerous genes in prokaryotes. The transport of mannitol through the phosphotransferase systems （PTS） is regulated by the CRP-cAMP complex. The aim of the study is to investigate how the CRP-cAMP complex acting on the mannitol PTS operon mtl of the Vibrio cholerae El Tot biotype. Methods The crp mutant strain was generated by homologous recombination to assess the need of CRP to activate the mannitol PTS operon of V. choleroe El Tor. Electrophoretic mobility shift assays （EMSA） and the reporter plasmid pBBRlux were used to confirm the role that the CRP-cAMP complex playing on the mannitol PTS operon intl. Results In this study, we confirmed that CRP is strictly needed for the activation of the mtl operon. We further experimentally identified five CRP binding sites within the promoter region upstream of the mannitol PTS operon mtl of the Vibrio cholerae El Tor biotype and found that these sites display different affinities for CRP and provide different contributions to the activation of the operon. Conclusion The five binding sites collectively confer the strong activation of mannitol transfer by CRP in V. choleroe, indicating an elaborate and subtle CRP activation mechanism.

第二信使cAMP在细菌压力应激与毒力调节中的作用

不同类型的第二信使分子在细菌生理活动中发挥着重要作用。环腺苷酸(3′,5′-cyclic adenosine monophosphate,cAMP)作为核苷类第二信使在细菌中普遍存在。正常生理条件下cAMP在细菌胞内的合成与代谢存在动态平衡,并通过与其受体蛋白(cAMP receptor protein,Crp)形成的复合体发挥转录调节作用。本文综述了cAMP-Crp在致死胁迫、细菌群体竞争和生物膜形成中的压力应激调节机制,以及cAMP在不同病原菌中影响毒力的作用途径,并呼吁研究者关注细菌cAMP响应宿主或外界环境变化的上游途径。全面了解cAMP介导的细菌应激和毒力调控,可能有助于细菌感染的防控与治疗。