1xyd
From Proteopedia
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| Ligands: | , | ||||||
| Gene: | S100b (Rattus norvegicus) | ||||||
| Related: | 1QLK, 1B4C, 1DT7, 1MWN, 3PSR, 1ODB
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
NMR Solution Structure of Rat Zinc-Calcium-S100B, 20 Structures
Overview
The EF-hand calcium-binding protein S100B also binds one zinc ion per subunit with a relatively high affinity (K(d) approximately 90 nM) [Wilder et al., (2003) Biochemistry 42, 13410-13421]. In this study, the structural characterization of zinc binding to calcium-loaded S100B was examined using high-resolution NMR techniques, including structural characterization of this complex in solution at atomic resolution. As with other S100 protein structures, the quaternary structure of Zn(2+)-Ca(2+)-bound S100B was found to be dimeric with helices H1, H1', H4, and H4' forming an X-type four-helix bundle at the dimer interface. NMR data together with mutational analyses are consistent with Zn(2+) coordination arising from His-15 and His-25 of one S100B subunit and from His-85 and Glu-89 of the other subunit. The addition of Zn(2+) was also found to extend helices H4 and H4' three to four residues similar to what was previously observed with the binding of target proteins to S100B. Furthermore, a kink in helix 4 was observed in Zn(2+)-Ca(2+)-bound S100B that is not in Ca(2+)-bound S100B. These structural changes upon Zn(2+)-binding could explain the 5-fold increase in affinity that Zn(2+)-Ca(2+)-bound S100B has for peptide targets such as the TRTK peptide versus Ca(2+)-bound S100B. There are also changes in the relative positioning of the two EF-hand calcium-binding domains and the respective helices comprising these EF-hands. Changes in conformation such as these could contribute to the order of magnitude higher affinity that S100B has for calcium in the presence of Zn(2+).
About this Structure
1XYD is a Single protein structure of sequence from Rattus norvegicus. Full crystallographic information is available from OCA.
Reference
Solution structure of zinc- and calcium-bound rat S100B as determined by nuclear magnetic resonance spectroscopy., Wilder PT, Varney KM, Weiss MB, Gitti RK, Weber DJ, Biochemistry. 2005 Apr 19;44(15):5690-702. PMID:15823027
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