Title Cytophaga hutchinsonii chu_2177, encoding the O-antigen ligase, is essential for cellulose degradation
Author Yahong Tan1, Wenxia Song1, Lijuan Gao1,2, Weican Zhang1, and Xuemei Lu1*
Address 1State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, P. R. China, 2School of Life Science and Technology, Weifang Medical University, Weifang 261000, P. R. China
Bibliography Journal of Microbiology, 60(4),364-374, 2022,
DOI 10.1007/s12275-022-1531-3
Key Words Cytophaga hutchinsonii, O-antigen ligase, cellulose degradation, T9SS cargo proteins, cellulase
Abstract 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.