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Title

A conserved phenylalanine of motif IV in superfamily 2 helicases is required for cooperative, ATP-dependent binding of RNA substrates in DEAD-box proteins

Authors
Banroques, Josette
Tanner, Kyle
Published in Molecular and Cellular Biology. 2008, vol. 28, no. 10, p. 3359-71
Abstract We have identified a highly conserved phenylalanine in motif IV of the DEAD-box helicases that is important for their enzymatic activities. In vivo analyses of essential proteins in yeast showed that mutants of this residue had severe growth phenotypes. Most of the mutants also were temperature sensitive, which suggested that the mutations altered the conformational stability. Intragenic suppressors of the F405L mutation in yeast Ded1 mapped close to regions of the protein involved in ATP or RNA binding in DEAD-box crystal structures, which implicated a defect at this level. In vitro experiments showed that these mutations affected ATP binding and hydrolysis as well as strand displacement activity. However, the most pronounced effect was the loss of the ATP-dependent cooperative binding of the RNA substrates. Sequence analyses and an examination of the Protein Data Bank showed that the motif IV phenylalanine is conserved among superfamily 2 helicases. The phenylalanine appears to be an anchor that maintains the rigidity of the RecA-like domain. For DEAD-box proteins, the phenylalanine also aligns a highly conserved arginine of motif VI through van der Waals and cation-pi interactions, thereby helping to maintain the network of interactions that exist between the different motifs involved in ATP and RNA binding.
Keywords Adenosine Triphosphate/metabolismAmino Acid MotifsAmino Acid SequenceArginine/chemistryBase SequenceConserved SequenceDEAD-box RNA Helicases/chemistry/genetics/metabolismKineticsModels, MolecularMutagenesis, Site-DirectedPhenotypePhenylalanine/chemistryRNA, Fungal/genetics/metabolismSaccharomyces cerevisiae/genetics/metabolismSaccharomyces cerevisiae Proteins/chemistry/genetics/metabolismSequence Homology, Amino AcidSubstrate SpecificitySuppression, Genetic
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PMID: 18332124
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Other version: http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=18332124
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Research group Acquisition et expression de facteurs de virulence chez Staphylococcus aureus (86)
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BANROQUES, Josette et al. A conserved phenylalanine of motif IV in superfamily 2 helicases is required for cooperative, ATP-dependent binding of RNA substrates in DEAD-box proteins. In: Molecular and Cellular Biology, 2008, vol. 28, n° 10, p. 3359-71. https://archive-ouverte.unige.ch/unige:917

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Deposited on : 2009-02-25

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