1BW5

THE NMR SOLUTION STRUCTURE OF THE HOMEODOMAIN OF THE RAT INSULIN GENE ENHANCER PROTEIN ISL-1, 50 STRUCTURES

Summary for 1BW5

• Entry DOI: 10.2210/pdb1bw5/pdb
• Descriptor: INSULIN GENE ENHANCER PROTEIN ISL-1 (1 entity in total)
• Functional Keywords: dna-binding protein, homeodomain, lim domain, dna binding protein
• Biological source: Rattus norvegicus (Norway rat)
• Cellular location: Nucleus: P50480
• Total number of polymer chains: 1
• Total formula weight: 7893.51

Authors

Ippel, J.H.,Larsson, G.,Behravan, G.,Zdunek, J.,Lundqvist, M.,Schleucher, J.,Lycksell, P.-O.,Wijmenga, S.S. (deposition date: 1998-09-29, release date: 1999-06-15, Last modification date: 2024-05-22)

Primary citation

Ippel, H.,Larsson, G.,Behravan, G.,Zdunek, J.,Lundqvist, M.,Schleucher, J.,Lycksell, P.O.,Wijmenga, S.
The solution structure of the homeodomain of the rat insulin-gene enhancer protein isl-1. Comparison with other homeodomains.
J.Mol.Biol., 288:689-703, 1999

PubMed Abstract: 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.

PubMed: 10329173
DOI: 10.1006/jmbi.1999.2718

Experimental method

SOLUTION NMR