4UA2

Crystal structure of dual function transcriptional regulator MerR from Bacillus megaterium MB1

Summary for 4UA2

• Entry DOI: 10.2210/pdb4ua2/pdb
• Related: 4UA1
• Descriptor: Regulatory protein (2 entities in total)
• Functional Keywords: metalloregulatory protein, dna binding protein
• Biological source: Bacillus megaterium
• Total number of polymer chains: 8
• Total formula weight: 130616.09

Authors

Lin, L.Y.,Chang, C.C.,Zou, X.W.,Huang, C.C.,Chan, N.L. (deposition date: 2014-08-07, release date: 2015-07-22, Last modification date: 2024-11-13)

Primary citation

Chang, C.C.,Lin, L.Y.,Zou, X.W.,Huang, C.C.,Chan, N.L.
Structural basis of the mercury(II)-mediated conformational switching of the dual-function transcriptional regulator MerR
Nucleic Acids Res., 43:7612-7623, 2015

PubMed Abstract: The mer operon confers bacterial resistance to inorganic mercury (Hg(2+)) and organomercurials by encoding proteins involved in sensing, transport and detoxification of these cytotoxic agents. Expression of the mer operon is under tight control by the dual-function transcriptional regulator MerR. The metal-free, apo MerR binds to the mer operator/promoter region as a repressor to block transcription initiation, but is converted into an activator upon Hg(2+)-binding. To understand how MerR interacts with Hg(2+) and how Hg(2+)-binding modulates MerR function, we report here the crystal structures of apo and Hg(2+)-bound MerR from Bacillus megaterium, corresponding respectively to the repressor and activator conformation of MerR. To our knowledge, the apo-MerR structure represents the first visualization of a MerR family member in its intact and inducer-free form. And the Hg(2+)-MerR structure offers the first view of a triligated Hg(2+)-thiolate center in a metalloprotein, confirming that MerR binds Hg(2+) via trigonal planar coordination geometry. Structural comparison revealed the conformational transition of MerR is coupled to the assembly/disassembly of a buried Hg(2+) binding site, thereby providing a structural basis for the Hg(2+)-mediated functional switching of MerR. The pronounced Hg(2+)-induced repositioning of the MerR DNA-binding domains suggests a plausible mechanism for the transcriptional regulation of the mer operon.

PubMed: 26150423
DOI: 10.1093/nar/gkv681

Experimental method

X-RAY DIFFRACTION (2.61 Å)