Structural insights into the molecular mechanism of Escherichia coli SdiA, a quorum-sensing receptor

Kim, T. and Duong, T. and Wu, C. A. and Choi, J. and Lan, N. and Kang, S. W. and Lokanath, N. K. and Shin, D. and Hwang, H. Y. and Kim, K. K. (2014) Structural insights into the molecular mechanism of Escherichia coli SdiA, a quorum-sensing receptor. Acta Crystallographica Section D: Biological Crystallography, 70 (3). pp. 694-707. ISSN 0907-4449

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Abstract

Escherichia coli SdiA is a quorum-sensing (QS) receptor that responds to autoinducers produced by other bacterial species to control cell division and virulence. Crystal structures reveal that E. coli SdiA, which is composed of an N-terminal ligand-binding domain and a C-terminal DNA-binding domain (DBD), forms a symmetrical dimer. Although each domain shows structural similarity to other QS receptors, SdiA differs from them in the relative orientation of the two domains, suggesting that its ligand-binding and DNA-binding functions are independent. Consistently, in DNA gel-shift assays the binding affinity of SdiA for the ftsQP2 promoter appeared to be insensitive to the presence of autoinducers. These results suggest that autoinducers increase the functionality of SdiA by enhancing the protein stability rather than by directly affecting the DNA-binding affinity. Structural analyses of the ligand-binding pocket showed that SdiA cannot accommodate ligands with long acyl chains, which was corroborated by isothermal titration calorimetry and thermal stability analyses. The formation of an intersubunit disulfide bond that might be relevant to modulation of the DNA-binding activity was predicted from the proximal position of two Cys residues in the DBDs of dimeric SdiA. It was confirmed that the binding affinity of SdiA for the uvrY promoter was reduced under oxidizing conditions, which suggested the possibility of regulation of SdiA by multiple independent signals such as quorum-sensing inducers and the oxidation state of the cell.

Item Type:	Article
Uncontrolled Keywords:	chemistry, metabolism, Crystallography, X ray crystallography, X-Ray, article, oxidative stress, signal transduction, Signal Transduction, quorum sensing, Ligands, protein binding, species difference, ligand, Protein Binding, Species Specificity, disulfide bonds, DNA binding protein, DNA-Binding Proteins, E coli, Escherichia coli protein, Escherichia coli Proteins, ligase, Ligases, N acylhomoserine lactone synthase, N-acylhomoserine lactone synthase, Quorum Sensing, SdiA, sdiA protein, Trans-Activators, transactivator protein
Subjects:	D Physical Science > Physics
Divisions:	Department of > Physics
Depositing User:	Arshiya Kousar Library Assistant
Date Deposited:	27 Jun 2019 06:43
Last Modified:	27 Jun 2019 06:43
URI:	http://eprints.uni-mysore.ac.in/id/eprint/3692

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