title: Atomic structure of the apoptosome: mechanism of cytochrome c- and dATP-mediated activation of Apaf-1.
abstract: The apoptotic protease-activating factor 1 (Apaf-1) controls the onset of many known forms of intrinsic apoptosis in mammals. Apaf-1 exists in normal cells as an autoinhibited monomer. Upon binding to cytochrome c and dATP, Apaf-1 oligomerizes into a heptameric complex known as the apoptosome, which recruits and activates cell-killing caspases. Here we present an atomic structure of an intact mammalian apoptosome at 3.8 Å resolution, determined by single-particle, cryo-electron microscopy (cryo-EM). Structural analysis, together with structure-guided biochemical characterization, uncovered how cytochrome c releases the autoinhibition of Apaf-1 through specific interactions with the WD40 repeats. Structural comparison with autoinhibited Apaf-1 revealed how dATP binding triggers a set of conformational changes that results in the formation of the apoptosome. Together, these results constitute the molecular mechanism of cytochrome c- and dATP-mediated activation of Apaf-1.
authors.affiliation: Ministry of Education Protein Science Laboratory, Center for Structural Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, China;
authors.forename: Mengying
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Ministry of Education Protein Science Laboratory, Center for Structural Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, China;
authors.forename: Yini
authors.initials: Y
authors.lastname: Li
authors.affiliation: Ministry of Education Protein Science Laboratory, Center for Structural Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, China;
authors.forename: Qi
authors.initials: Q
authors.lastname: Hu
authors.affiliation: MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, United Kingdom.
authors.forename: Xiao-Chen
authors.initials: XC
authors.lastname: Bai
authors.affiliation: Ministry of Education Protein Science Laboratory, Center for Structural Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, China;
authors.forename: Weiyun
authors.initials: W
authors.lastname: Huang
authors.affiliation: Ministry of Education Protein Science Laboratory, Center for Structural Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, China;
authors.forename: Chuangye
authors.initials: C
authors.lastname: Yan
authors.affiliation: MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, United Kingdom.
authors.forename: Sjors H W
authors.initials: SH
authors.lastname: Scheres
authors.affiliation: Ministry of Education Protein Science Laboratory, Center for Structural Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, China;
authors.forename: Yigong
authors.initials: Y
authors.lastname: Shi
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D053478:Apoptosomes / Q000737:chemistry*; D053477:Apoptotic Protease-Activating Factor 1 / Q000378:metabolism*; D053453:Caspase 9 / Q000378:metabolism; D002460:Cell Line; D020285:Cryoelectron Microscopy; D045304:Cytochromes c / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation / Q000502:physiology; D006801:Humans; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D017434:Protein Structure, Tertiary
chemical_list: D053478:Apoptosomes; D053477:Apoptotic Protease-Activating Factor 1; D000255:Adenosine Triphosphate; D045304:Cytochromes c; D053453:Caspase 9
keywords: Apaf-1; apoptosis; apoptosome; caspase activation; caspase-9; cryo-EM structure