1by4
From Proteopedia
STRUCTURE AND MECHANISM OF THE HOMODIMERIC ASSEMBLY OF THE RXR ON DNA
Overview
The 9-cis retinoic acid receptor, RXR, binds DNA effectively as a homodimer or as a heterodimer with other nuclear receptors. The DNA-binding sites for these RXR complexes are direct repeats of a consensus sequence separated by one to five base-pairs of intervening space. Here, we report the 2.1 A crystal structure of the RXR-DNA-binding domain as a homodimer in complex with its idealized direct repeat DNA target. The structure shows how a gene-regulatory site can induce conformational changes in a transcription factor that promote homo-cooperative assembly. Specifically, an alpha-helix in the T-box is disrupted to allow efficient DNA-binding and subunit dimerization. RXR displays a relaxed mode of sequence recognition, interacting with only three base-pairs in each hexameric half-site. The structure illustrates how site selection is achieved in this large eukaryotic transcription factor family through discrete protein-protein interactions and the use of tandem DNA binding sites with characteristic spacings.
About this Structure
1BY4 is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Structural basis of RXR-DNA interactions., Zhao Q, Chasse SA, Devarakonda S, Sierk ML, Ahvazi B, Rastinejad F, J Mol Biol. 2000 Feb 18;296(2):509-20. PMID:10669605 Page seeded by OCA on Fri May 2 12:06:18 2008
