Large conformation shifts of Vibrio cholerae VqmA dimer in the absence of target DNA provide insight into DNA-binding mechanisms of LuxR-type receptors

• Published in: Biochemical and biophysical research communications Vol. 520; no. 2; pp. 399 - 405
• Main Authors: Wu, Hai, Li, Minjun, Peng, Chao, Yin, Yue, Guo, Haojie, Wang, Weiwei, Xu, Qin, Zhou, Huan, Xu, Chunyan, Yu, Feng, He, Jianhua
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 03.12.2019
• Subjects: Crystal structure; Disulfide bond; DNA-Binding mechanism; Protein-DNA interaction; Quorum sensing; Transcription promoter; Quorum sensing; DNA-Binding mechanism; Protein-DNA interaction; Transcription promoter; Disulfide bond; Crystal structure
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2019.10.063

Quorum sensing regulates the biofilm formation and expression of virulence factors in Vibrio cholerae, an obligate human pathogen that continues to imperil human health. Cytoplasmic transcription factor VqmA is a LuxR-type receptor ubiquitous in the Vibrio genus and one vibriophage VP882 and plays an important role in V. cholerae pathogenicity. Here we presented the X-ray crystal structure of V. cholerae VqmA–DPO complex and compared it with the previously determined VqmA–DPO–DNA complex. To our knowledge, this is the first report on the crystal structures of the same LuxR-type receptor with two conformations of binding to DNA and not binding to DNA. Based on the results of structural analysis and biochemical assays, we revealed the secondary structure of the linker region between two function domains changed significantly, and DNA binding domains were covalently linked by a disulfide bond formed by the highly conserved Cys134. Besides, the distance between two DBD monomers became longer than that in DNA-binding conformation, and two α8 helixes underwent a large conformation shift. The results of the structure-function analyses presented here improve our understanding of the complex mechanisms in the conformational changes of LuxR-type receptors caused by DNA binding. •The same LuxR-type receptor with two crystal structures of DNA binding or not.•DBDs were more flexible in the absence of DNA and disulfide bonds.•Cys134 Disulfide bond serves as a switch for conformations of VqmA.•α5 helix has strong isomerization ability and acts as a flexible spring.•The mechanisms in the conformation shift of VqmA caused by DNA binding.