Cytophaga hutchinsonii can efficiently degrade crystalline
cellulose, in which the cell surface cellulases secreted by the
type IX secretion system (T9SS) play important roles, but
the degradation mechanism remains unclear, and the anchor
mechanism of cellulases on the outer membrane in C.
hutchinsonii has not been studied. Here, chu_2177 was identified
by transposon mutagenesis and was proved to be indispensable
for cellulose utilization in C. hutchinsonii. Disruption
of chu_2177 resulted in O-antigen deficiency and chu_
177 could confer O-antigen ligase activity upon an Escherichia
coli waal mutant, indicating that chu_2177 encoded the Ontigen
ligase. Moreover, deletion of chu_2177 caused defects
in cellulose utilization, cell motility, biofilm formation, and
stress resistance. Further study showed that the endoglucanase
activity was markedly decreased in the outer membrane
but was increased in the culture fluid without chu_2177.
Western blot proved that endoglucanase CHU_1336 was not
located on the outer membrane but was released in the culture
fluid of the Δ2177 mutant. Further proteomics analysis
showed that many cargo proteins of T9SS were missing in
the outer membrane of the Δ2177 mutant. Our study revealed
that the deletion of chu_2177 affected the localization of
many T9SS cargo proteins including cellulases on the outer
membrane of C. hutchinsonii.
Citations
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Screening and genome-wide analysis of lignocellulose-degrading bacteria from humic soil Tianjiao Zhang, Shuli Wei, Yajie Liu, Chao Cheng, Jie Ma, Linfang Yue, Yanrong Gao, Yuchen Cheng, Yongfeng Ren, Shaofeng Su, Xiaoqing Zhao, Zhanyuan Lu Frontiers in Microbiology.2023;[Epub] CrossRef
The type IX secretion system: Insights into its function and connection to glycosylation in Cytophaga hutchinsonii Wenxia Song, Xueke Zhuang, Yahong Tan, Qingsheng Qi, Xuemei Lu Engineering Microbiology.2022; 2(3): 100038. CrossRef