1s98

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spinqualitylabelsall models PDB ID 1s98 Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image
, resolution 2.30Å
Gene:	YFHF, B2528, C3053, Z3795, ECS3394, SF2575, S2747 (Escherichia coli)
Resources:	FirstGlance, OCA, PDBsum, RCSB
Coordinates:	save as pdb, mmCIF, xml

E.coli IscA crystal structure to 2.3 A

Overview

IscA, an 11 kDa member of the hesB family of proteins, binds iron and [2Fe-2S] clusters, and participates in the biosynthesis of iron-sulfur proteins. We report the crystal structure of the apo-protein form of IscA from Escherichia coli to a resolution of 2.3A. The crystals belong to the space group P3(2)21 and have unit cell dimensions a=b=66.104 A, c=150.167 A (alpha=beta=90 degrees, gamma=120 degrees ). The structure was solved using single-wavelength anomalous dispersion (SAD) phasing of a selenomethionyl derivative, and the IscA model was refined to R=21.4% (Rfree=25.4%). IscA exists as an (alpha1alpha2)2 homotetramer with the (alpha1alpha2) dimer comprising the asymmetric unit. Cys35, implicated in Fe-S cluster assembly, is located in a central cavity formed at the tetramer interface with the gamma-sulfur atoms of residues from the alpha1 and alpha2' monomers (and alpha1'alpha2) positioned close to one another (approximately equal 7 A). C-terminal residues 99-107 are disordered, and the exact positions of Cys99 and Cys101 could not be determined. However, computer modeling of C-terminal residues in the tetramer suggests that Cys99 and Cys101 in the alpha1 monomer and those of the alpha1' monomer (or alpha2 and alpha2') are positioned sufficiently close to coordinate [2Fe-2S] clusters between the two dimers, whereas this is not possible within the (alpha1alpha2) or (alpha1'alpha2') dimer. This symmetrical arrangement allows for binding of two [2Fe-2S] clusters on opposite sides of the tetramer. Modeling further reveals that Cys101 is positioned sufficiently close to Cys35 to allow Cys35 to participate in cluster assembly, formation, or transfer.

About this Structure

1S98 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Crystal structure of IscA, an iron-sulfur cluster assembly protein from Escherichia coli., Cupp-Vickery JR, Silberg JJ, Ta DT, Vickery LE, J Mol Biol. 2004 Apr 16;338(1):127-37. PMID:15050828

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