Cu(I)-mediated allosteric switching in a copper-sensing operon repressor (CsoR).
The copper-sensing operon repressor (CsoR) is representative of a major Cu(I)-sensing family of bacterial metalloregulatory proteins that has evolved to prevent cytoplasmic copper toxicity. It is unknown how Cu(I) binding to tetrameric CsoRs mediates transcriptional derepression of copper resistance genes. A phylogenetic analysis of 227 DUF156 protein members, including biochemically or structurally characterized CsoR/RcnR repressors, reveals that Geobacillus thermodenitrificans (Gt) CsoR characterized here is representative of CsoRs from pathogenic bacilli Listeria monocytogenes and Bacillus anthracis. The 2.56 Å structure of Cu(I)-bound Gt CsoR reveals that Cu(I) binding induces a kink in the α2-helix between two conserved copper-ligating residues and folds an N-terminal tail (residues 12-19) over the Cu(I) binding site. NMR studies of Gt CsoR reveal that this tail is flexible in the apo-state with these dynamics quenched upon Cu(I) binding. Small angle x-ray scattering experiments on an N-terminally truncated Gt CsoR (Δ2-10) reveal that the Cu(I)-bound tetramer is hydrodynamically more compact than is the apo-state. The implications of these findings for the allosteric mechanisms of other CsoR/RcnR repressors are discussed.
From the Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102.
Feng-Ming James
FM
Chang
From the Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102.
H Jerome
HJ
Coyne
the Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos, México, 04510.
Ciro
C
Cubillas
the Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos, México, 04510.
Pablo
P
Vinuesa
the Structural Biophysics Laboratory, Center for Cancer Research, NCI-National Institutes of Health, Frederick, Maryland 21702-1201, and.
Xianyang
X
Fang
the Department of Microbiology, Cornell University, Ithaca, New York 14853-8101.
Zhen
Z
Ma
From the Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102.
Dejian
D
Ma
the Department of Microbiology, Cornell University, Ithaca, New York 14853-8101.
John D
JD
Helmann
the Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos, México, 04510.
Alejandro
A
García-de los Santos
the Structural Biophysics Laboratory, Center for Cancer Research, NCI-National Institutes of Health, Frederick, Maryland 21702-1201, and.
Yun-Xing
YX
Wang
From the Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102.
Charles E
CE
Dann
From the Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, giedroc@indiana.edu.
David P
DP
Giedroc
D000494:Allosteric Regulation / Q000187:drug effects; D001408:Bacillus anthracis / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D003300:Copper / Q000378:metabolism* / Q000494:pharmacology; D004269:DNA, Bacterial / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D056506:Geobacillus / Q000378:metabolism; D008958:Models, Molecular; D009876:Operon / Q000235:genetics*; D010802:Phylogeny; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012097:Repressor Proteins; D003300:Copper
Copper; Metal Sensor Protein; Metalloregulation; Phylogenetics; Transcription Repressor; X-ray Crystallography; X-ray Scattering