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Structural basis for copper/silver binding by the Synechocystis metallochaperone CopM
Author(s) -
Zhao Shun,
Wang Xiao,
Niu Guoqi,
Dong Wei,
Wang Jia,
Fang Ying,
Lin Yajing,
Liu Lin
Publication year - 2016
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.374
H-Index - 138
ISSN - 2059-7983
DOI - 10.1107/s2059798316011943
Subject(s) - copper , synechocystis , crystallography , chemistry , divalent , efflux , biophysics , biochemistry , biology , gene , organic chemistry , mutant
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.