5KB1: Crystal Structure Of A Tris-thiolate Hg(ii) Complex In A De Novo Three Stranded Coiled Coil Peptide

Preorganization and predisposition are important molecular recognition concepts exploited by nature to obtain site-specific and selective metal binding to proteins. While native structures containing an MS3 core are often unavailable in both apo- and holo-forms, one can use designed three-stranded coiled coils (3SCCs) containing tris-thiolate sites to evaluate these concepts. We show that the preferred metal geometry dictates the degree to which the cysteine rotamers change upon metal complexation. The Cys ligands in the apo-form are preorganized for binding trigonal pyramidal species (Pb(II)S3 and As(III)S3) in an endo conformation oriented toward the 3SCC C-termini, whereas the cysteines are predisposed for trigonal planar Hg(II)S3 and 4-coordinate Zn(II)S3O structures, requiring significant thiol rotation for metal binding. This study allows assessment of the importance of protein fold and side-chain reorientation for achieving metal selectivity in human retrotransposons and metalloregulatory proteins.
PDB ID: 5KB1Download
MMDB ID: 142616
PDB Deposition Date: 2016/6/2
Updated in MMDB: 2017/10
Experimental Method:
x-ray diffraction
Resolution: 2.09  Å
Source Organism:
Similar Structures:
Biological Unit for 5KB1: trimeric; determined by author and by software (PISA)
Molecular Components in 5KB1
Label Count Molecule
Proteins (3 molecules)
Hg(ii)zn(ii)(grand Coil Ser-l16cl30h)3+
Molecule annotation
Chemicals (6 molecules)
* Click molecule labels to explore molecular sequence information.

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