1bw5
From Proteopedia
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
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THE NMR SOLUTION STRUCTURE OF THE HOMEODOMAIN OF THE RAT INSULIN GENE ENHANCER PROTEIN ISL-1, 50 STRUCTURES
Overview
Homeodomains are one of the key families of eukaryotic DNA-binding motifs and provide an important model system for DNA recognition. We have determined a high-quality nuclear magnetic resonance (NMR) structure of the DNA-binding homeodomain of the insulin gene enhancer protein Isl-1 (Isl-1-HD). It forms the first solution structure of a homeodomain from the LIM family. It contains a well-defined inner core (residues 12-55) consisting of the classical three-helix structure observed in other homeodomains. The N terminus is unstructured up to residue 8, while the C terminus gradually becomes unstructured from residue 55 onwards. Some flexibility is evident in the loop parts of the inner core. Isl-1-HD has, despite its low sequence identity (23-34 %), a structure that is strikingly similar to that of the other homeodomains with known three-dimensional structures. Detailed analysis of Isl-1-HD and the other homeodomains rationalizes the differences in their temperature stability and explains the low stability of the Isl-1-HD in the free state (tm 22-30 degrees C). Upon DNA binding, a significant stabilization occurs (tm>55 degrees C). The low stability of Isl-1-HD (and other mammalian homeodomains) suggests that in vivo Isl-1-HD recognizes its cognate DNA from its unfolded state.
About this Structure
1BW5 is a Single protein structure of sequence from Rattus norvegicus. Full crystallographic information is available from OCA.
Reference
The solution structure of the homeodomain of the rat insulin-gene enhancer protein isl-1. Comparison with other homeodomains., Ippel H, Larsson G, Behravan G, Zdunek J, Lundqvist M, Schleucher J, Lycksell PO, Wijmenga S, J Mol Biol. 1999 May 14;288(4):689-703. PMID:10329173
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