RIG-I Uses an ATPase-Powered Translocation-Throttling Mechanism for Kinetic Proofreading of RNAs and Oligomerization

Mol Cell. 2018 Oct 18;72(2):355-368.e4. doi: 10.1016/j.molcel.2018.08.021. Epub 2018 Sep 27.

Abstract

RIG-I has a remarkable ability to specifically select viral 5'ppp dsRNAs for activation from a pool of cytosolic self-RNAs. The ATPase activity of RIG-I plays a role in RNA discrimination and activation, but the underlying mechanism was unclear. Using transient-state kinetics, we elucidated the ATPase-driven "kinetic proofreading" mechanism of RIG-I activation and RNA discrimination, akin to DNA polymerases, ribosomes, and T cell receptors. Even in the autoinhibited state of RIG-I, the C-terminal domain kinetically discriminates against self-RNAs by fast off rates. ATP binding facilitates dsRNA engagement but, interestingly, makes RIG-I promiscuous, explaining the constitutive signaling by Singleton-Merten syndrome-linked mutants that bind ATP without hydrolysis. ATP hydrolysis dissociates self-RNAs faster than 5'ppp dsRNA but, more importantly, drives RIG-I oligomerization through translocation, which we show to be regulated by helicase motif IVa. RIG-I translocates directionally from the dsRNA end into the stem region, and the 5'ppp end "throttles" translocation to provide a mechanism for threading and building a signaling-active oligomeric complex.

Keywords: ATP; RIG-I; RNA discrimination; innate immunity; kinetic proofreading; kinetics; oligomerization; self-versus-non-self; translocation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

MeSH terms

  • Adenosine Triphosphatases / metabolism*
  • Adenosine Triphosphate / metabolism
  • Aortic Diseases / metabolism
  • Cell Line
  • DEAD Box Protein 58 / metabolism*
  • DEAD-box RNA Helicases / metabolism
  • Dental Enamel Hypoplasia / metabolism
  • Female
  • HEK293 Cells
  • Humans
  • Hydrolysis
  • Kinetics
  • Metacarpus / abnormalities
  • Metacarpus / metabolism
  • Muscular Diseases / metabolism
  • Odontodysplasia / metabolism
  • Osteoporosis / metabolism
  • Protein Binding / physiology
  • RNA / metabolism*
  • RNA, Double-Stranded / metabolism
  • Receptors, Antigen, T-Cell / metabolism
  • Ribosomes / metabolism
  • Signal Transduction / physiology
  • Vascular Calcification / metabolism

Substances

  • RNA, Double-Stranded
  • Receptors, Antigen, T-Cell
  • RNA
  • Adenosine Triphosphate
  • Adenosine Triphosphatases
  • DDX58 protein, human
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases

Supplementary concepts

  • Singleton Merten syndrome