Structural basis for cytosolic double-stranded RNA surveillance by human oligoadenylate synthetase 1

Jesse Donovan, Matthew Dufner, Alexei Korennykh

Research output: Contribution to journalArticle

81 Scopus citations

Abstract

The human sensor of double-stranded RNA (dsRNA) oligoadenylate synthetase 1 (hOAS1) polymerizes ATP into 2',5'-linked iso-RNA (2-5A) involved in innate immunity, cell cycle, and differentiation. We report the crystal structure of hOAS1 in complex with dsRNA and 2'-deoxy ATP at 2.7 Å resolution, which reveals the mechanism of cytoplasmic dsRNA recognition and activation of oligoadenylate synthetases. Human OAS1 recognizes dsRNA using a previously uncharacterized protein/RNA interface that forms via a conformational change induced by binding of dsRNA. The protein/RNA interface involves two minor grooves and has no sequence-specific contacts, with the exception of a single hydrogen bond between the-NH2 groupofnucleobase G17 and the carbonyl oxygen ofserine 56. Using a biochemical readout, we show that hOAS1 undergoes more than 20,000-fold activation upon dsRNA binding and that canonical or GU-wobble substitutions produce dsRNA mutants that retain either full or partial activity, in agreement with the crystal structure. Ultimately, the binding of dsRNA promotes an elaborate conformational rearrangement in the N-terminal lobe of hOAS1, which brings residues D75, D77, and D148 into proximity and creates coordination geometry for binding of two catalytic Mg2+ ions and ATP. The assembly of this critical active-site structure provides the gate that couples binding of dsRNA to the production and downstream functions of 2-5A.

Original languageEnglish (US)
Pages (from-to)1652-1657
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume110
Issue number5
DOIs
StatePublished - Jan 29 2013

All Science Journal Classification (ASJC) codes

  • General

Keywords

  • CCA-adding enzyme
  • Cytokine
  • Interferon response
  • Nucleotidyl transferase
  • PAP1

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