title: The Activation Mechanism of 2'-5'-Oligoadenylate Synthetase Gives New Insights Into OAS/cGAS Triggers of Innate Immunity.
abstract: 2'-5'-Oligoadenylate synthetases (OASs) produce the second messenger 2'-5'-oligoadenylate, which activates RNase L to induce an intrinsic antiviral state. We report on the crystal structures of catalytic intermediates of OAS1 including the OAS1·dsRNA complex without substrates, with a donor substrate, and with both donor and acceptor substrates. Combined with kinetic studies of point mutants and the previously published structure of the apo form of OAS1, the new data suggest a sequential mechanism of OAS activation and show the individual roles of each component. They reveal a dsRNA-mediated push-pull effect responsible for large conformational changes in OAS1, the catalytic role of the active site Mg(2+), and the structural basis for the 2'-specificity of product formation. Our data reveal similarities and differences in the activation mechanisms of members of the OAS/cyclic GMP-AMP synthase family of innate immune sensors. In particular, they show how helix 3103-α5 blocks the synthesis of cyclic dinucleotides by OAS1.
authors.affiliation: Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Lohöfener
authors.affiliation: Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Nicola
authors.initials: N
authors.lastname: Steinke
authors.affiliation: Institute for Virology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Penelope
authors.initials: P
authors.lastname: Kay-Fedorov
authors.affiliation: Research Division for Structural Analysis, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Baruch
authors.affiliation: Institute of Protein Research, Russian Academy of Science, 142290 Pushchino, Moscow Region, Russian Federation.
authors.forename: Alexey
authors.initials: A
authors.lastname: Nikulin
authors.affiliation: Institute of Protein Research, Russian Academy of Science, 142290 Pushchino, Moscow Region, Russian Federation.
authors.forename: Svetlana
authors.initials: S
authors.lastname: Tishchenko
authors.affiliation: Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany; Research Division for Structural Analysis, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Dietmar J
authors.initials: DJ
authors.lastname: Manstein
authors.affiliation: Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany; Research Division for Structural Analysis, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany. Electronic address: fedorov.roman@mh-hannover.de.
authors.forename: Roman
authors.initials: R
authors.lastname: Fedorov
mesh_terms: D015088:2',5'-Oligoadenylate Synthetase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004789:Enzyme Activation; D007113:Immunity, Innate; D008274:Magnesium / Q000378:metabolism; D008958:Models, Molecular; D009713:Nucleotidyltransferases / Q000737:chemistry / Q000378:metabolism; D017354:Point Mutation; D017433:Protein Structure, Secondary; D012330:RNA, Double-Stranded / Q000737:chemistry* / Q000378:metabolism; D013552:Swine / Q000235:genetics / Q000276:immunology* / Q000378:metabolism
chemical_list: D012330:RNA, Double-Stranded; D009713:Nucleotidyltransferases; D015088:2',5'-Oligoadenylate Synthetase; D008274:Magnesium