Variable primary coordination environments of Cd(ɪɪ) binding to three helix bundles provide a pathway for rapid metal exchange

TY - JOUR

T1 - Variable primary coordination environments of Cd(ɪɪ) binding to three helix bundles provide a pathway for rapid metal exchange

AU - Tebo, Alison G.

AU - Hemmingsen, Lars Bo Stegeager

AU - Pecoraro, Vincent L.

PY - 2015/12

Y1 - 2015/12

N2 - Members of the ArsR/SmtB family of transcriptional repressors, such as CadC, regulate the intracellular levels of heavy metals like Cd(ii), Hg(ii), and Pb(ii). These metal sensing proteins bind their target metals with high specificity and affinity, however, a lack of structural information about these proteins makes defining the coordination sphere of the target metal difficult. Lingering questions as to the identity of Cd(ii) coordination in CadC are addressed via protein design techniques. Two designed peptides with tetrathiolate metal binding sites were prepared and characterized, revealing fast exchange between CdS3O and CdS4 coordination spheres. Correlation of (111m)Cd PAC spectroscopy and (113)Cd NMR spectroscopy suggests that Cd(ii) coordinated to CadC is in fast exchange between CdS3O and CdS4 forms, which may provide a mechanism for rapid sensing of heavy metal contaminants by this regulatory protein.

AB - Members of the ArsR/SmtB family of transcriptional repressors, such as CadC, regulate the intracellular levels of heavy metals like Cd(ii), Hg(ii), and Pb(ii). These metal sensing proteins bind their target metals with high specificity and affinity, however, a lack of structural information about these proteins makes defining the coordination sphere of the target metal difficult. Lingering questions as to the identity of Cd(ii) coordination in CadC are addressed via protein design techniques. Two designed peptides with tetrathiolate metal binding sites were prepared and characterized, revealing fast exchange between CdS3O and CdS4 coordination spheres. Correlation of (111m)Cd PAC spectroscopy and (113)Cd NMR spectroscopy suggests that Cd(ii) coordinated to CadC is in fast exchange between CdS3O and CdS4 forms, which may provide a mechanism for rapid sensing of heavy metal contaminants by this regulatory protein.

U2 - 10.1039/c5mt00228a

DO - 10.1039/c5mt00228a

M3 - Journal article

C2 - 26503746

SN - 1756-5901

VL - 7

SP - 1555

EP - 1561

JO - Metallomics

JF - Metallomics

IS - 12

ER -