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Proc Natl Acad Sci U S A. 2000 Nov 21;97(24):13080-5.

Crystal structure of yeast initiation factor 4A, a DEAD-box RNA helicase.

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Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.


The eukaryotic translation initiation factor 4A (eIF4A) is a member of the DEA(D/H)-box RNA helicase family, a diverse group of proteins that couples an ATPase activity to RNA binding and unwinding. Previous work has provided the structure of the amino-terminal, ATP-binding domain of eIF4A. Extending those results, we have solved the structure of the carboxyl-terminal domain of eIF4A with data to 1.75 A resolution; it has a parallel alpha-beta topology that superimposes, with minor variations, on the structures and conserved motifs of the equivalent domain in other, distantly related helicases. Using data to 2.8 A resolution and molecular replacement with the refined model of the carboxyl-terminal domain, we have completed the structure of full-length eIF4A; it is a "dumbbell" structure consisting of two compact domains connected by an extended linker. By using the structures of other helicases as a template, compact structures can be modeled for eIF4A that suggest (i) helicase motif IV binds RNA; (ii) Arg-298, which is conserved in the DEA(D/H)-box RNA helicase family but is absent from many other helicases, also binds RNA; and (iii) motifs V and VI "link" the carboxyl-terminal domain to the amino-terminal domain through interactions with ATP and the DEA(D/H) motif, providing a mechanism for coupling ATP binding and hydrolysis with conformational changes that modulate RNA binding.

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