[ODP-087] Regulation of chitinase gene expression by small RNA and Hfq in Serratia
Chitin is an abundant biomass resource that exists as a structural polysaccharide in the exoskeleton of crustaceans, insects, and the cell walls of fungi, et al. Serratia plymuthica produces chitinases to degrade and utilize chitin. In our previous studies on Serratia marcescens, transcriptional activator ChiR and uptake of (GlcNAc)2 were required to produce the chitinases. ChiX small RNA contained a complementary sequence to the 5´ UTRs of chiP encoding chitoporin and chiR mRNAs. ChiX was thought to make base pairs with 5´ UTR of chiP mRNA, suggesting that the chiP transcription derepressed the post-transcriptional regulation of chiR by ChiX. We showed that S. plymuthica also has the same ChiX-based regulation as S. marcescens. In this study, the hfq, encoding RNA chaperon Hfq, and chiX genes on the chromosome were replaced with Kanamycin cassette in S. plymuthica. The chiX::kan mutant showed higher chitin degradation ability than the wild-type strain, but hfq::kan mutant did not produce chitinases. Then, we constructed the hfq::kan chiX::Sp/Sm double mutant The double mutant did not produce chitinases. These results suggest that the regulation of chitinase gene expression by Hfq is not directly related to the repression of chiR by ChiX.