2i4i

From Proteopedia

Revision as of 11:49, 23 January 2008

Crystal Structure of human DEAD-box RNA helicase DDX3X

Overview

DExD-box helicases are involved in all aspects of cellular RNA metabolism., Conserved domains 1 and 2 contain nine signature motifs that are, responsible for nucleotide binding, RNA binding and ATP hydrolysis. The, human DEAD-box helicase DDX3X has been associated with several different, cellular processes, such as cell-growth control, mRNA transport and, translation, and is suggested to be essential for the export of, unspliced/partially spliced HIV mRNAs from the nucleus to the cytoplasm., Here, the crystal structure of conserved domains 1 and 2 of DDX3X, including a DDX3-specific insertion that is not generally found in human, DExD-box helicases, is presented. The N-terminal domain 1 and the, C-terminal domain 2 both display RecA-like folds comprising a central, beta-sheet flanked by alpha-helices. Interestingly, the DDX3X-specific, insertion forms a helical element that extends a highly positively charged, sequence in a loop, thus increasing the RNA-binding surface of the, protein. Surprisingly, although DDX3X was crystallized in the presence of, a large excess of ADP or the slowly hydrolyzable ATP analogue ATPgammaS, the contaminant AMP was seen in the structure. A fluorescent-based, stability assay showed that the thermal stability of DDX3X was increased, by the mononucleotide AMP but not by ADP or ATPgammaS, suggesting that, DDX3X is stabilized by AMP and elucidating why AMP was found in the, nucleotide-binding pocket.

About this Structure

2I4I is a Single protein structure of sequence from Homo sapiens with as ligand. Full crystallographic information is available from OCA.

Reference

Crystal Structure of Conserved Domains 1 and 2 of the Human DEAD-box Helicase DDX3X in Complex with the Mononucleotide AMP., Hogbom M, Collins R, van den Berg S, Jenvert RM, Karlberg T, Kotenyova T, Flores A, Hedestam GB, Schiavone LH, J Mol Biol. 2007 Sep 7;372(1):150-9. Epub 2007 Jun 26. PMID:17631897

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