4LFU

Crystal structure of Escherichia coli SdiA in the space group C2

Summary for 4LFU

• Entry DOI: 10.2210/pdb4lfu/pdb
• Related: 4LGW
• Descriptor: Regulatory protein SdiA, TETRAETHYLENE GLYCOL, CHLORIDE ION, ... (4 entities in total)
• Functional Keywords: luxr-type quorum sensing receptor, transcription factor, dna binding protein
• Biological source: Escherichia coli
• Total number of polymer chains: 1
• Total formula weight: 29679.85

Authors

Kim, T.,Duong, T.,Wu, C.A.,Choi, J.,Lan, N.,Kang, S.W.,Lokanath, N.K.,Shin, D.,Hwang, H.Y.,Kim, K.K. (deposition date: 2013-06-27, release date: 2014-03-19, Last modification date: 2024-03-20)

Primary citation

Kim, T.,Duong, T.,Wu, C.A.,Choi, J.,Lan, N.,Kang, S.W.,Lokanath, N.K.,Shin, D.,Hwang, H.Y.,Kim, K.K.
Structural insights into the molecular mechanism of Escherichia coli SdiA, a quorum-sensing receptor
Acta Crystallogr.,Sect.D, 70:694-707, 2014

PubMed 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.

PubMed: 24598739
DOI: 10.1107/S1399004713032355

Experimental method

X-RAY DIFFRACTION (2.26 Å)