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Crystal structure of dual function transcriptional regulator MerR from Bacillus megaterium MB1Crystal structure of dual function transcriptional regulator MerR from Bacillus megaterium MB1
Structural highlights
Publication Abstract from PubMedThe mer operon confers bacterial resistance to inorganic mercury (Hg2+) 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 Hg2+-binding. To understand how MerR interacts with Hg2+ and how Hg2+-binding modulates MerR function, we report here the crystal structures of apo and Hg2+-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 Hg2+-MerR structure offers the first view of a triligated Hg2+-thiolate center in a metalloprotein, confirming that MerR binds Hg2+ via trigonal planar coordination geometry. Structural comparison revealed the conformational transition of MerR is coupled to the assembly/disassembly of a buried Hg2+ binding site, thereby providing a structural basis for the Hg2+-mediated functional switching of MerR. The pronounced Hg2+-induced repositioning of the MerR DNA-binding domains suggests a plausible mechanism for the transcriptional regulation of the mer operon. Structural basis of the mercury(II)-mediated conformational switching of the dual-function transcriptional regulator MerR.,Chang CC, Lin LY, Zou XW, Huang CC, Chan NL Nucleic Acids Res. 2015 Jul 6. pii: gkv681. PMID:26150423[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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