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Title: Structural basis for a hand-like site in the calcium sensor CatchER with fast kinetics

Authors:
; ; ; ; ; ;  [1]
  1. (GSU)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
UNIVERSITYNIH
OSTI Identifier:
1120051
Resource Type:
Journal Article
Resource Relation:
Journal Name: Acta Crystallogr. D; Journal Volume: 69; Journal Issue: (12) ; 12, 2013
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Zhang, Ying, Reddish, Florence, Tang, Shen, Zhuo, You, Wang, Yuan-Fang, Yang, Jenny J., and Weber, Irene T. Structural basis for a hand-like site in the calcium sensor CatchER with fast kinetics. United States: N. p., 2014. Web. doi:10.1107/S0907444913021306.
Zhang, Ying, Reddish, Florence, Tang, Shen, Zhuo, You, Wang, Yuan-Fang, Yang, Jenny J., & Weber, Irene T. Structural basis for a hand-like site in the calcium sensor CatchER with fast kinetics. United States. doi:10.1107/S0907444913021306.
Zhang, Ying, Reddish, Florence, Tang, Shen, Zhuo, You, Wang, Yuan-Fang, Yang, Jenny J., and Weber, Irene T. Thu . "Structural basis for a hand-like site in the calcium sensor CatchER with fast kinetics". United States. doi:10.1107/S0907444913021306.
@article{osti_1120051,
title = {Structural basis for a hand-like site in the calcium sensor CatchER with fast kinetics},
author = {Zhang, Ying and Reddish, Florence and Tang, Shen and Zhuo, You and Wang, Yuan-Fang and Yang, Jenny J. and Weber, Irene T.},
abstractNote = {},
doi = {10.1107/S0907444913021306},
journal = {Acta Crystallogr. D},
number = (12) ; 12, 2013,
volume = 69,
place = {United States},
year = {Thu Jul 17 00:00:00 EDT 2014},
month = {Thu Jul 17 00:00:00 EDT 2014}
}
  • High-resolution crystal structures of the designed calcium sensor CatchER revealed snapshots of calcium and gadolinium ions binding within the designed site in agreement with its fast kinetics. Calcium ions, which are important signaling molecules, can be detected in the endoplasmic reticulum by an engineered mutant of green fluorescent protein (GFP) designated CatchER with a fast off-rate. High resolution (1.78–1.20 Å) crystal structures were analyzed for CatchER in the apo form and in complexes with calcium or gadolinium to probe the binding site for metal ions. While CatchER exhibits a 1:1 binding stoichiometry in solution, two positions were observed for eachmore » of the metal ions bound within the hand-like site formed by the carboxylate side chains of the mutated residues S147E, S202D, Q204E, F223E and T225E that may be responsible for its fast kinetic properties. Comparison of the structures of CatchER, wild-type GFP and enhanced GFP confirmed that different conformations of Thr203 and Glu222 are associated with the two forms of Tyr66 of the chromophore which are responsible for the absorbance wavelengths of the different proteins. Calcium binding to CatchER may shift the equilibrium for conformational population of the Glu222 side chain and lead to further changes in its optical properties.« less
  • The flagellar calcium-binding protein (FCaBP) of the protozoan Trypanosoma cruzi is targeted to the flagellar membrane where it regulates flagellar function and assembly. As a first step toward understanding the Ca{sup 2+}-induced conformational changes important for membrane-targeting, we report here the x-ray crystal structure of FCaBP in the Ca{sup 2+}-free state determined at 2.2{angstrom} resolution. The first 17 residues from the N terminus appear unstructured and solvent-exposed. Residues implicated in membrane targeting (Lys-19, Lys-22, and Lys-25) are flanked by an exposed N-terminal helix (residues 26-37), forming a patch of positive charge on the protein surface that may interact electrostatically withmore » flagellar membrane targets. The four EF-hands in FCaBP each adopt a 'closed conformation' similar to that seen in Ca{sup 2+}-free calmodulin. The overall fold of FCaBP is closest to that of grancalcin and other members of the penta EF-hand superfamily. Unlike the dimeric penta EF-hand proteins, FCaBP lacks a fifth EF-hand and is monomeric. The unstructured N-terminal region of FCaBP suggests that its covalently attached myristoyl group at the N terminus may be solvent-exposed, in contrast to the highly sequestered myristoyl group seen in recoverin and GCAP1. NMR analysis demonstrates that the myristoyl group attached to FCaBP is indeed solvent-exposed in both the Ca{sup 2+}-free and Ca{sup 2+}-bound states, and myristoylation has no effect on protein structure and folding stability. We propose that exposed acyl groups at the N terminus may anchor FCaBP to the flagellar membrane and that Ca{sup 2+}-induced conformational changes may control its binding to membrane-bound protein targets..« less
  • No abstract prepared.
  • Type V and VI mammalian adenylyl cyclases (AC5, AC6) are inhibited by Ca{sup 2+} at both sub- and supramicromolar concentration. This inhibition may provide feedback in situations where cAMP promotes opening of Ca{sup 2+} channels, allowing fine control of cardiac contraction and rhythmicity in cardiac tissue where AC5 and AC6 predominate. Ca{sup 2+} inhibits the soluble AC core composed of the C1 domain of AC5 (VC1) and the C2 domain of AC2 (IIC2). As observed for holo-AC5, inhibition is biphasic, showing 'high-affinity' (K{sub i} = {approx}0.4 {mu}M) and 'low-affinity' (K{sub i} = {approx}100 {mu}M) modes of inhibition. At micromolar concentration,more » Ca{sup 2+} inhibition is nonexclusive with respect to pyrophosphate (PP{sub i}), a noncompetitive inhibitor with respect to ATP, but at >100 {mu}M Ca{sup 2+}, inhibition appears to be exclusive with respect to PP{sub i}. The 3.0 {angstrom} resolution structure of G{alpha}s{center_dot}GTP{gamma}S/forskolin-activated VC1:IIC2 crystals soaked in the presence of ATP{alpha}S and 8 {mu}M free Ca{sup 2+} contains a single, loosely coordinated metal ion. ATP soaked into VC1:IIC2 crystals in the presence of 1.5 mM Ca{sup 2+} is not cyclized, and two calcium ions are observed in the 2.9 {angstrom} resolution structure of the complex. In both of the latter complexes VC1:IIC2 adopts the 'open', catalytically inactive conformation characteristic of the apoenzyme, in contrast to the 'closed', active conformation seen in the presence of ATP analogues and Mg{sup 2+} or Mn{sup 2+}. Structures of the pyrophosphate (PP{sub i}) complex with 10 mM Mg{sup 2+} (2.8 {angstrom}) or 2 mM Ca{sup 2+} (2.7 {angstrom}) also adopt the open conformation, indicating that the closed to open transition occurs after cAMP release. In the latter complexes, Ca{sup 2+} and Mg{sup 2+} bind only to the high-affinity 'B' metal site associated with substrate/product stabilization. Ca{sup 2+} thus stabilizes the inactive conformation in both ATP- and PP{sub i}-bound states.« less