Structural basis for copper/silver binding by the Synechocystis metallochaperone CopM.
Copper homeostasis integrates multiple processes from sensing to storage and efflux out of the cell. CopM is a cyanobacterial metallochaperone, the gene for which is located upstream of a two-component system for copper resistance, but the molecular basis for copper recognition by this four-helical bundle protein is unknown. Here, crystal structures of CopM in apo, copper-bound and silver-bound forms are reported. Monovalent copper/silver ions are buried within the bundle core; divalent copper ions are found on the surface of the bundle. The monovalent copper/silver-binding site is constituted by two consecutive histidines and is conserved in a previously functionally unknown protein family. The structural analyses show two conformational states and suggest that flexibility in the first α-helix is related to the metallochaperone function. These results also reveal functional diversity from a protein family with a simple four-helical fold.
Key Laboratory of Photobiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China.
Shun
S
Zhao
Key Laboratory of Photobiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China.
Xiao
X
Wang
College of Life Sciences, Capital Normal University, Beijing 100048, People's Republic of China.
Guoqi
G
Niu
Key Laboratory of Photobiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China.
Wei
W
Dong
Key Laboratory of Photobiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China.
Jia
J
Wang
Key Laboratory of Photobiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China.
Ying
Y
Fang
Laboratory of Non-coding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, People's Republic of China.
Yajing
Y
Lin
Key Laboratory of Photobiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, People's Republic of China.
Lin
L
Liu
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D003300:Copper / Q000378:metabolism*; D018360:Crystallography, X-Ray; D056511:Metallochaperones / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D016415:Sequence Alignment; D012834:Silver / Q000378:metabolism*; D046939:Synechocystis / Q000737:chemistry* / Q000378:metabolism
D001426:Bacterial Proteins; D056511:Metallochaperones; D012834:Silver; D003300:Copper
copper homeostasis; copper-binding protein; helical bundle; metal coordination