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

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

SUBMITTER: Banroques J 

PROVIDER: S-EPMC2423170 | biostudies-literature | 2008 May

REPOSITORIES: biostudies-literature