Identification and characterization of a novel locus in Cytophaga hutchinsonii involved in colony spreading and cellulose digestion
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Cytophaga hutchinsonii, an aerobic cellulolytic soil bacterium, is capable of degrading crystalline cellulose and gliding over surface rapidly. The involved mechanisms, however, are largely unknown. Here, we used the mariner-based transposon HimarEm1 to screen for C. hutchinsonii mutants deficient in utilizing filter paper as the sole carbon source. A novel gene locus, chu_1719, encoding a hypothetical protein was identified, whose inactivation resulted in a compromised growth of C. hutchinsonii on filter paper. Further analysis revealed that disruption of chu_1719 suppressed colony spreading but had no significant effect on Avicel degradation in liquid medium. Carboxymethylcellulase (CMCase) activity of the mutant membrane proteins was reduced by about 40 % as compared with the wild-type strain. Moreover, profiles of cellulose-adsorbed outer membrane proteins were significantly different between the mutant and wild-type (WT) strains. These results suggest that chu_1719 plays an important role in controlling the spreading motility and cellulose utilization probably by affecting the appropriate production of membrane proteins in C. hutchinsonii.
KeywordsCytophaga hutchinsonii Transposon insertion Colony spreading Membrane proteins Cellulose digestion
We are grateful for Dr. MJ McBride for providing the plasmids and strains. This work is supported by grants from the National Basic Research Program (2011CB707402), the National Natural Science Foundation of China (31170762), New Century Excellent Talents in University (NCET-10-0546), Shandong Provincial Funds for Distinguished Young Scientists (JQ201108). We also thank the anonymous reviewers for their constructive comments.
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