2gxu

From Proteopedia

Revision as of 15:10, 20 March 2008

HERA N-terminal domain in complex with orthophosphate, crystal form 1

Overview

DEAD box RNA helicases use the energy of ATP hydrolysis to unwind double-stranded RNA regions or to disrupt RNA/protein complexes. A minimal RNA helicase comprises nine conserved motifs distributed over two RecA-like domains. The N-terminal domain contains all motifs involved in nucleotide binding, namely the Q-motif, the DEAD box, and the P-loop, as well as the SAT motif, which has been implicated in the coordination of ATP hydrolysis and RNA unwinding. We present here the crystal structure of the N-terminal domain of the Thermus thermophilus RNA helicase Hera in complex with adenosine monophosphate (AMP). Upon binding of AMP the P-loop adopts a partially collapsed or half-open conformation that is still connected to the DEAD box motif, and the DEAD box in turn is linked to the SAT motif via hydrogen bonds. This network of interactions communicates changes in the P-loop conformation to distant parts of the helicase. The affinity of AMP is comparable to that of ADP and ATP, substantiating that the binding energy from additional phosphate moieties is directly converted into conformational changes of the entire helicase. Importantly, the N-terminal Hera domain forms a dimer in the crystal similar to that seen in another thermophilic prokaryote. It is possible that this mode of dimerization represents the prototypic architecture in RNA helicases of thermophilic origin.

About this Structure

2GXU is a Single protein structure of sequence from Thermus thermophilus. Full crystallographic information is available from OCA.

Reference

Crystal structure and nucleotide binding of the Thermus thermophilus RNA helicase Hera N-terminal domain., Rudolph MG, Heissmann R, Wittmann JG, Klostermeier D, J Mol Biol. 2006 Aug 25;361(4):731-43. Epub 2006 Jul 12. PMID:16890241

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