AUTHOR=Liu Long , Li Feiyu , Xu Li , Wang Jingjie , Li Moran , Yuan Jie , Wang Hui , Yang Ruiping , Li Bei 

TITLE=Cyclic AMP-CRP Modulates the Cell Morphology of Klebsiella pneumoniae in High-Glucose Environment

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.02984

DOI=10.3389/fmicb.2019.02984

ISSN=1664-302X

ABSTRACT=<p>Bacteria can modify their morphology in response to environmental stimuli for survival or host defense evasion. The rich glucose <italic>in vivo</italic> or in the Luria–Bertani (LB) medium shortened the cell length of <italic>Klebsiella pneumoniae</italic>. The environmental glucose decreased the levels of cyclic AMP (cAMP) and the transcription of <italic>crp</italic>, which declined the cAMP–cAMP receptor protein (cAMP-CRP) activity. The cell length of <italic>crp</italic> deletion mutant was significantly shorter than that of the wild type (0.981 ± 0.057 μm vs. 2.415 ± 0.075 μm, <italic>P</italic> &lt; 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 <italic>crp</italic> deletion strain. Five of them (<italic>omp</italic>A, <italic>tol</italic>B, <italic>ybg</italic>C, <italic>fts</italic>I, and <italic>rcs</italic>F) were selected to verify their expression in the high-glucose environment, and overexpression of <italic>tol</italic>B or <italic>rcs</italic>F shortened the bacterial length similar to that of the <italic>crp</italic> deletion strain. Electrophoretic mobility shift assay indicated that CRP directly negatively regulates the transcription of <italic>tol</italic>B and <italic>rcs</italic>F 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 <italic>K. pneumoniae</italic>.</p>