Bacteria can modify their morphology in response to environmental stimuli for survival or host defense evasion. The rich glucose in vivo or in the Luria-Bertani (LB) medium shortened the cell length of Klebsiella pneumoniae. The environmental glucose decreased the levels of cyclic AMP (cAMP) and the transcription of crp, which declined the cAMP-cAMP receptor protein (cAMP-CRP) activity. The cell length of crp deletion mutant was significantly shorter than that of the wild type (0.981 ± 0.057 μm vs. 2.415 ± 0.075 μm, P < 0.001). These results indicated that the high environmental glucose alters the bacterial morphology to a round form through regulating the activity of cAMP-CRP complex. Comparative proteomics analysis showed increased expression of 10 proteins involved in cell division or cell wall biosynthesis in the crp deletion strain. Five of them (ompA, tolB, ybgC, ftsI, and rcsF) were selected to verify their expression in the high-glucose environment, and overexpression of tolB or rcsF shortened the bacterial length similar to that of the crp deletion strain. Electrophoretic mobility shift assay indicated that CRP directly negatively regulates the transcription of tolB and rcsF by binding to the promoter regions. This study first proved the role and partial regulation mechanism of CRP in altering cell morphology during infection and provided a theoretical basis for elucidating the mechanism in diabetes mellitus susceptible to K. pneumoniae.

中文翻译：

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循环AMP-CRP在高葡萄糖环境中调节肺炎克雷伯菌的细胞形态。

细菌可以响应环境刺激而改变其形态，以生存或逃避宿主防御。体内或Luria-Bertani（LB）培养基中富含的葡萄糖缩短了肺炎克雷伯菌的细胞长度。环境葡萄糖降低了环AMP（cAMP）的水平和crp的转录，从而降低了cAMP-cAMP受体蛋白（cAMP-CRP）的活性。crp缺失突变体的细胞长度明显短于野生型（0.981±0.057μmvs. 2.415±0.075μm，P <0.001）。这些结果表明，高环境葡萄糖通过调节cAMP-CRP复合物的活性将细菌形态改变为圆形。比较蛋白质组学分析显示，在crp缺失菌株中，参与细胞分裂或细胞壁生物合成的10种蛋白质表达增加。选择其中五个（ompA，tolB，ybgC，ftsI和rcsF）以验证它们在高葡萄糖环境中的表达，并且tolB或rcsF的过表达缩短了细菌的长度，类似于crp缺失菌株。电泳迁移率迁移分析表明，CRP通过与启动子区结合直接直接调节tolB和rcsF的转录。这项研究首先证明了CRP在感染过程中改变细胞形态的作用和部分调节机制，并为阐明易患肺炎克雷伯菌的糖尿病的机制提供了理论基础。电泳迁移率迁移分析表明，CRP通过与启动子区结合直接直接调节tolB和rcsF的转录。这项研究首先证明了CRP在感染过程中改变细胞形态的作用和部分调节机制，并为阐明易患肺炎克雷伯菌的糖尿病的机制提供了理论基础。电泳迁移率迁移分析表明，CRP通过与启动子区结合直接直接调节tolB和rcsF的转录。这项研究首先证明了CRP在感染过程中改变细胞形态的作用和部分调节机制，并为阐明易患肺炎克雷伯菌的糖尿病的机制提供了理论基础。