A Xylose-sensing Transcriptional Factor XbpR And Its Regulatory Function In Mycobacterium Smegmatis

D-Xylose,the most abundant monosaccharide besides glucose in nature,can serve as carbon and energy source for many bacteria.However,there are few reports on the special mechanism of D-xylose metabolism and the mono saccharide-involved gene regulation in mycobacteria.Based on the previous works in our laboratory,we study the regulatory function of a new xylose-sensing transcriptional factor designated as XbpR in Mycobacterium smegmatis.The main results are as follows:(1)Using bacterial one-hybrid assays,XbpR was shown to interact with its own promoter.The ChIP and EMSA experiments confirmed that the interaction was specific both in vitro and in vivo in M.smegmatis.(2)?-galactosidase activity assays confirmed that XbpR served as a repressor.(3)ITC assay found that D-xylose could directly interact with XbpR protein.(4)Using EMSA and ?-galactosidase activity assays,we showed that D-xylose could reduce the repression of the DNA-binding activity by XbpR.(5)Bacterial growth assays confirmed that the xbpR-overexpressed strain was more sensitive to RFP than the wildtype strain.By contrast,the xbpR-deleted M.smegmatis strain was more resistant to RFP.Taken together,this study reports a new xylose-sensing regulator and its regulaton on the mycobacterial growth and drug resistance.This work provides new clues for further exploring the mechanism of xylose metabolism and the monosaccharide-involved gene regulation in mycobacteria.