title: The RNA annealing mechanism of the HIV-1 Tat peptide: conversion of the RNA into an annealing-competent conformation.
abstract: The annealing of nucleic acids to (partly) complementary RNA or DNA strands is involved in important cellular processes. A variety of proteins have been shown to accelerate RNA/RNA annealing but their mode of action is still mainly uncertain. In order to study the mechanism of protein-facilitated acceleration of annealing we selected a short peptide, HIV-1 Tat(44-61), which accelerates the reaction efficiently. The activity of the peptide is strongly regulated by mono- and divalent cations which hints at the importance of electrostatic interactions between RNA and peptide. Mutagenesis of the peptide illustrated the dominant role of positively charged amino acids in RNA annealing--both the overall charge of the molecule and a precise distribution of basic amino acids within the peptide are important. Additionally, we found that Tat(44-61) drives the RNA annealing reaction via entropic rather than enthalpic terms. One-dimensional-NMR data suggest that the peptide changes the population distribution of possible RNA structures to favor an annealing-prone RNA conformation, thereby increasing the fraction of colliding RNA molecules that successfully anneal.
authors.affiliation: Max F Perutz Laboratories, Dr Bohrgasse 9/5, 1030 Vienna, Austria.
authors.forename: Martina
authors.initials: M
authors.lastname: Doetsch
authors.forename: Boris
authors.initials: B
authors.lastname: Fürtig
authors.forename: Thomas
authors.initials: T
authors.lastname: Gstrein
authors.forename: Sabine
authors.initials: S
authors.lastname: Stampfl
authors.forename: Renée
authors.initials: R
authors.lastname: Schroeder
mesh_terms: D024361:Amino Acids, Basic / Q000502:physiology; D002412:Cations / Q000737:chemistry; D019277:Entropy; D016296:Mutagenesis; D009690:Nucleic Acid Conformation; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D012313:RNA / Q000737:chemistry*; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D024361:Amino Acids, Basic; D002412:Cations; D010446:Peptide Fragments; D054322:tat Gene Products, Human Immunodeficiency Virus; D012313:RNA