title: Rearrangement of structured RNA via branch migration structures catalysed by the highly related DEAD-box proteins p68 and p72.
abstract: RNA helicases, like their DNA-specific counterparts, can function as processive enzymes, unwinding RNA with a defined step size in a unidirectional fashion. Recombinant nuclear DEAD-box protein p68 and its close relative p72 are reported here to function in a similar fashion, though the processivity of both RNA helicases appears to be limited to only a few consecutive catalytic steps. The two proteins resemble each other also with regard to other biochemical properties. We have found that both proteins exhibit an RNA annealing in addition to their helicase activity. By using both these activities the enzymes are able in vitro to catalyse rearrangements of RNA secondary structures that otherwise are too stable to be resolved by their low processive helicase activities. RNA rearrangement proceeds via protein induced formation and subsequent resolution of RNA branch migration structures, whereby the latter step is dependent on ATP hydrolysis. The analysed DEAD-box proteins are reminiscent of certain DNA helicases, for example those found in bacteriophages T4 and T7, that catalyse homologous DNA strand exchange in cooperation with the annealing activity of specific single strand binding proteins.
authors.affiliation: Medizinische Biochemie und Molekularbiologie, Universität des Saarlandes, D-66421 Homburg, Germany.
authors.forename: O G
authors.initials: OG
authors.lastname: Rössler
authors.forename: A
authors.initials: A
authors.lastname: Straka
authors.forename: H
authors.initials: H
authors.lastname: Stahl
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D020816:Amino Acid Motifs; D020029:Base Pairing; D002384:Catalysis; D053487:DEAD-box RNA Helicases; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020365:RNA Helicases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020871:RNA Stability; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D011995:Recombination, Genetic / Q000235:genetics; D017384:Sequence Deletion / Q000235:genetics; D017385:Sequence Homology
chemical_list: D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D012313:RNA; D000255:Adenosine Triphosphate; D011494:Protein Kinases; D000251:Adenosine Triphosphatases; C102004:DDX17 protein, human; C506749:Ddx5 protein, human; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases