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Gong GQ, Anandapadamanaban M, Islam MS, Hay IM, Bourguet M, Špokaitė S, Dessus AN, Ohashi Y, Perisic O, Williams RL. Making PI3K superfamily enzymes run faster. Adv Biol Regul 2024:101060. [PMID: 39592347 DOI: 10.1016/j.jbior.2024.101060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2024] [Accepted: 11/16/2024] [Indexed: 11/28/2024]
Abstract
The phosphoinositide 3-kinase (PI3K) superfamily includes lipid kinases (PI3Ks and type III PI4Ks) and a group of PI3K-like Ser/Thr protein kinases (PIKKs: mTOR, ATM, ATR, DNA-PKcs, SMG1 and TRRAP) that have a conserved C-terminal kinase domain. A common feature of the superfamily is that they have very low basal activity that can be greatly increased by a range of regulatory factors. Activators reconfigure the active site, causing a subtle realignment of the N-lobe of the kinase domain relative to the C-lobe. This realignment brings the ATP-binding loop in the N-lobe closer to the catalytic residues in the C-lobe. In addition, a conserved C-lobe feature known as the PIKK regulatory domain (PRD) also can change conformation, and PI3K activators can alter an analogous PRD-like region. Recent structures have shown that diverse activating influences can trigger these conformational changes, and a helical region clamping onto the kinase domain transmits regulatory interactions to bring about the active site realignment for more efficient catalysis. A recent report of a small-molecule activator of PI3Kα for application in nerve regeneration suggests that flexibility of these regulatory elements might be exploited to develop specific activators of all PI3K superfamily members. These activators could have roles in wound healing, anti-stroke therapy and treating neurodegeneration. We review common structural features of the PI3K superfamily that may make them amenable to activation.
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Affiliation(s)
- Grace Q Gong
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK; University College London Cancer Institute, University College London, London, UK
| | | | - Md Saiful Islam
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Iain M Hay
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Maxime Bourguet
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Saulė Špokaitė
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Antoine N Dessus
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Yohei Ohashi
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Olga Perisic
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Roger L Williams
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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2
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McCombs AM, Armendariz JR, Falke JJ. Ras signaling mechanisms: New insights from single-molecule biophysics. Biophys J 2024; 123:3277-3280. [PMID: 39217418 PMCID: PMC11480753 DOI: 10.1016/j.bpj.2024.08.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2024] [Revised: 08/23/2024] [Accepted: 08/29/2024] [Indexed: 09/04/2024] Open
Affiliation(s)
- Anne Marie McCombs
- Molecular Biophysics Program and Department of Biochemistry, University of Colorado, Boulder, Colorado
| | - Joy R Armendariz
- Molecular Biophysics Program and Department of Biochemistry, University of Colorado, Boulder, Colorado
| | - Joseph J Falke
- Molecular Biophysics Program and Department of Biochemistry, University of Colorado, Boulder, Colorado.
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3
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Zhao Z, Wei Z, Zheng J, Li Z, Zou H, Wen X, Li F, Wang X, Huang Q, Zeng H, Fan H, Cai X, Zhang J, Jia B, Huang A, Lu M, Lin Y. Hepatitis B virus promotes its own replication by enhancing RAB5A-mediated dual activation of endosomal and autophagic vesicle pathways. Emerg Microbes Infect 2023; 12:2261556. [PMID: 37725090 PMCID: PMC10614717 DOI: 10.1080/22221751.2023.2261556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 09/17/2023] [Indexed: 09/21/2023]
Abstract
Chronic hepatitis B virus (HBV) infection remains one of the major global public health concerns, and it develop into liver fibrosis, cirrhosis, and hepatocellular carcinoma. Recent evidence suggests that endosomal and autophagic vesicles are beneficial for HBV replication. However, it has not been well elucidated how HBV exploits such intracellular vesicle systems for its replication. RAB5A, a member of small GTPase family, plays crucial roles in early endosome biogenesis and autophagy initiation. We observed that RAB5A mRNA and protein levels were significantly increased in HBV-expressing hepatoma cell lines as well as in liver tissue samples from chronic HBV-infected patients. Moreover, RAB5A silencing inhibited HBV replication and subviral particle (SVP) expression significantly in HBV-transfected and -infected hepatoma cells, whereas RAB5A overexpression increased them. Mechanistically, RAB5A increases HBV replication through enhancement of early endosome (EE) - late endosome (LE) activation by interacting with EEA1, as well as enhancing autophagy induction by interacting with VPS34. Additionally, HBV infection enhances RAB5A-mediated dual activation of EE-LE system and autophagy. Collectively, our findings highlight that HBV utilizes RAB5A-mediated dual activation of endosomal and autophagic vesicle pathways for its own replication and persistence. Therefore, RAB5A is a potential target for chronic HBV infection treatment.
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Affiliation(s)
- Zhenyu Zhao
- Key Laboratory of Molecular Biology of Infectious Diseases (Chinese Ministry of Education), Chongqing Medical University, Chongqing, People’s Republic of China
| | - Zhen Wei
- Key Laboratory of Molecular Biology of Infectious Diseases (Chinese Ministry of Education), Chongqing Medical University, Chongqing, People’s Republic of China
| | - Jiaxin Zheng
- Key Laboratory of Molecular Biology of Infectious Diseases (Chinese Ministry of Education), Chongqing Medical University, Chongqing, People’s Republic of China
| | - Zhihong Li
- Key Laboratory of Molecular Biology of Infectious Diseases (Chinese Ministry of Education), Chongqing Medical University, Chongqing, People’s Republic of China
| | - Hecun Zou
- Institute of Life Sciences, Chongqing Medical University, Chongqing, People’s Republic of China
| | - Xiang Wen
- Key Laboratory of Infectious and Parasitic Diseases in Chongqing, Department of Infectious Diseases, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China
| | - Fahong Li
- Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China
| | - Xueyu Wang
- Institute for Virology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Qian Huang
- Key Laboratory of Molecular Biology of Infectious Diseases (Chinese Ministry of Education), Chongqing Medical University, Chongqing, People’s Republic of China
| | - Huaqing Zeng
- Key Laboratory of Molecular Biology of Infectious Diseases (Chinese Ministry of Education), Chongqing Medical University, Chongqing, People’s Republic of China
| | - Hui Fan
- Key Laboratory of Molecular Biology of Infectious Diseases (Chinese Ministry of Education), Chongqing Medical University, Chongqing, People’s Republic of China
| | - Xuefei Cai
- Key Laboratory of Molecular Biology of Infectious Diseases (Chinese Ministry of Education), Chongqing Medical University, Chongqing, People’s Republic of China
| | - Jiming Zhang
- Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China
| | - Bei Jia
- Key Laboratory of Infectious and Parasitic Diseases in Chongqing, Department of Infectious Diseases, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China
| | - Ailong Huang
- Key Laboratory of Molecular Biology of Infectious Diseases (Chinese Ministry of Education), Chongqing Medical University, Chongqing, People’s Republic of China
| | - Mengji Lu
- Institute for Virology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Yong Lin
- Key Laboratory of Molecular Biology of Infectious Diseases (Chinese Ministry of Education), Chongqing Medical University, Chongqing, People’s Republic of China
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4
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Gordon MT, Ziemba BP, Falke JJ. PDK1:PKCα heterodimer association-dissociation dynamics in single-molecule diffusion tracks on a target membrane. Biophys J 2023; 122:2301-2310. [PMID: 36733254 PMCID: PMC10257113 DOI: 10.1016/j.bpj.2023.01.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 12/01/2022] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
Previous studies have documented the formation of a heterodimer between the two protein kinases PDK1 and PKCα on a lipid bilayer containing their target lipids. This work investigates the association-dissociation kinetics of this PDK1:PKCα heterodimer. The approach monitors the two-dimensional diffusion of single, membrane-associated PDK1 molecules for diffusivity changes as PKCα molecules bind and unbind. In the absence of PKCα, a membrane-associated PDK1 molecule exhibits high diffusivity (or large diffusion constant, D) because its membrane-contacting PH domain binds the target PIP3 lipid headgroup with little bilayer penetration, yielding minimal frictional drag against the bilayer. In contrast, membrane-associated PKCα contacts the bilayer via its C1A, C1B, and C2 domains, which each bind at least one target lipid with significant bilayer insertion, yielding a large frictional drag and low diffusivity. The present findings reveal that individual fluor-PDK1 molecules freely diffusing on the membrane surface undergo reversible switching between distinct high and low diffusivity states, corresponding to the PDK1 monomer and the PDK1:PKCα heterodimer, respectively. The observed single-molecule diffusion trajectories are converted to step length time courses, then subjected to two-state, hidden Markov modeling and dwell time analysis. The findings reveal that both the PDK1 monomer state and the PDK1:PKCα heterodimer state decay via simple exponential kinetics, yielding estimates of rate constants for state switching in both directions. Notably, the PDK1:PKCα heterodimer has been shown to competitively inhibit PDK1 phosphoactivation of AKT1, and is believed to play a tumor suppressor role by limiting excess activation of the highly oncogenic PDK1/AKT1/mTOR pathway. Thus, the present elucidation of the PDK1:PKCα association-dissociation kinetics has important biological and medical implications. More broadly, the findings illustrate the power of single-molecule diffusion measurements to reveal the kinetics of association-dissociation events in membrane signaling reactions that yield a large change in diffusive mobility.
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Affiliation(s)
- Moshe T Gordon
- Molecular Biophysics Program and Department of Biochemistry, University of Colorado, Boulder, Colorado
| | - Brian P Ziemba
- Molecular Biophysics Program and Department of Biochemistry, University of Colorado, Boulder, Colorado
| | - Joseph J Falke
- Molecular Biophysics Program and Department of Biochemistry, University of Colorado, Boulder, Colorado.
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5
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Kotzampasi DM, Premeti K, Papafotika A, Syropoulou V, Christoforidis S, Cournia Z, Leondaritis G. The orchestrated signaling by PI3Kα and PTEN at the membrane interface. Comput Struct Biotechnol J 2022; 20:5607-5621. [PMID: 36284707 PMCID: PMC9578963 DOI: 10.1016/j.csbj.2022.10.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 10/03/2022] [Accepted: 10/03/2022] [Indexed: 11/16/2022] Open
Abstract
The oncogene PI3Kα and the tumor suppressor PTEN represent two antagonistic enzymatic activities that regulate the interconversion of the phosphoinositide lipids PI(4,5)P2 and PI(3,4,5)P3 in membranes. As such, they are defining components of phosphoinositide-based cellular signaling and membrane trafficking pathways that regulate cell survival, growth, and proliferation, and are often deregulated in cancer. In this review, we highlight aspects of PI3Kα and PTEN interplay at the intersection of signaling and membrane trafficking. We also discuss the mechanisms of PI3Kα- and PTEN- membrane interaction and catalytic activation, which are fundamental for our understanding of the structural and allosteric implications on signaling at the membrane interface and may aid current efforts in pharmacological targeting of these proteins.
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Affiliation(s)
- Danai Maria Kotzampasi
- Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece
- Department of Biology, University of Crete, Heraklion 71500, Greece
| | - Kyriaki Premeti
- Laboratory of Pharmacology, Faculty of Medicine, University of Ioannina, Ioannina 45110, Greece
| | - Alexandra Papafotika
- Laboratory of Biological Chemistry, Faculty of Medicine, School of Health Sciences, University of Ioannina, Ioannina 45110, Greece
- Biomedical Research Institute, Foundation for Research and Technology, Ioannina 45110, Greece
| | - Vasiliki Syropoulou
- Laboratory of Pharmacology, Faculty of Medicine, University of Ioannina, Ioannina 45110, Greece
| | - Savvas Christoforidis
- Laboratory of Biological Chemistry, Faculty of Medicine, School of Health Sciences, University of Ioannina, Ioannina 45110, Greece
- Biomedical Research Institute, Foundation for Research and Technology, Ioannina 45110, Greece
| | - Zoe Cournia
- Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece
| | - George Leondaritis
- Laboratory of Pharmacology, Faculty of Medicine, University of Ioannina, Ioannina 45110, Greece
- Institute of Biosciences, University Research Center of Ioannina, Ioannina 45110, Greece
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6
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Class III PI3K Biology. Curr Top Microbiol Immunol 2022; 436:69-93. [DOI: 10.1007/978-3-031-06566-8_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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7
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Ohashi Y. Activation Mechanisms of the VPS34 Complexes. Cells 2021; 10:cells10113124. [PMID: 34831348 PMCID: PMC8624279 DOI: 10.3390/cells10113124] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 11/09/2021] [Accepted: 11/09/2021] [Indexed: 01/18/2023] Open
Abstract
Phosphatidylinositol-3-phosphate (PtdIns(3)P) is essential for cell survival, and its intracellular synthesis is spatially and temporally regulated. It has major roles in two distinctive cellular pathways, namely, the autophagy and endocytic pathways. PtdIns(3)P is synthesized from phosphatidylinositol (PtdIns) by PIK3C3C/VPS34 in mammals or Vps34 in yeast. Pathway-specific VPS34/Vps34 activity is the consequence of the enzyme being incorporated into two mutually exclusive complexes: complex I for autophagy, composed of VPS34/Vps34-Vps15/Vps15-Beclin 1/Vps30-ATG14L/Atg14 (mammals/yeast), and complex II for endocytic pathways, in which ATG14L/Atg14 is replaced with UVRAG/Vps38 (mammals/yeast). Because of its involvement in autophagy, defects in which are closely associated with human diseases such as cancer and neurodegenerative diseases, developing highly selective drugs that target specific VPS34/Vps34 complexes is an essential goal in the autophagy field. Recent studies on the activation mechanisms of VPS34/Vps34 complexes have revealed that a variety of factors, including conformational changes, lipid physicochemical parameters, upstream regulators, and downstream effectors, greatly influence the activity of these complexes. This review summarizes and highlights each of these influences as well as clarifying key questions remaining in the field and outlining future perspectives.
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Affiliation(s)
- Yohei Ohashi
- MRC Laboratory of Molecular Biology, Protein and Nucleic Acid Chemistry Division, Francis Crick Avenue, Cambridge CB2 0QH, UK
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8
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Gordon MT, Ziemba BP, Falke JJ. Single-molecule studies reveal regulatory interactions between master kinases PDK1, AKT1, and PKC. Biophys J 2021; 120:5657-5673. [PMID: 34673053 DOI: 10.1016/j.bpj.2021.10.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 09/30/2021] [Accepted: 10/13/2021] [Indexed: 12/26/2022] Open
Abstract
Leukocyte migration is controlled by a leading-edge chemosensory pathway that generates the regulatory lipid phosphatidylinositol-3,4,5-trisphosphate (PIP3), a growth signal, thereby driving leading-edge expansion up attractant gradients toward sites of infection, inflammation, or tissue damage. PIP3 also serves as an important growth signal in growing cells and oncogenesis. The kinases PDK1, AKT1 or PKB, and PKCα are key components of a plasma-membrane-based PIP3 and Ca2+ signaling circuit that regulates these processes. PDK1 and AKT1 are recruited to the membrane by PIP3, whereas PKCα is recruited to the membrane by Ca2+. All three of these master kinases phosphoregulate an array of protein targets. For example, PDK1 activates AKT1, PKCα, and other AGC kinases by phosphorylation at key sites. PDK1 is believed to form PDK1-AKT1 and PDK1-PKCα heterodimers stabilized by a PDK1-interacting fragment (PIF) interaction between the PDK1 PIF pocket and the PIF motif of the AGC binding partner. Here, we present the first, to our knowledge, single-molecule studies of full-length PDK1 and AKT1 on target membrane surfaces, as well as their interaction with full-length PKCα. These studies directly detect membrane-bound PDK1-AKT1 and PDK1-PKCα heterodimers stabilized by PIF interactions formed at physiological ligand concentrations. PKCα exhibits eightfold higher PDK1 affinity than AKT1 and can competitively displace AKT1 from PDK1-AKT1 heterodimers. Ensemble activity measurements under matched conditions reveal that PDK1 activates AKT1 via a cis mechanism by phosphorylating an AKT1 molecule in the same PDK1-AKT1 heterodimer, whereas PKCα acts as a competitive inhibitor of this phosphoactivation reaction by displacing AKT1 from PDK1. Overall, the findings provide insights into the binding and regulatory interactions of the three master kinases on their target membrane and suggest that a recently described tumor suppressor activity of PKC isoforms may arise from its ability to downregulate PDK1-AKT1 phosphoactivation in the PIP3-PDK1-AKT1-mTOR pathway linked to cell growth and oncogenesis.
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Affiliation(s)
- Moshe T Gordon
- Molecular Biophysics Program and Department of Biochemistry, University of Colorado, Boulder, Colorado
| | - Brian P Ziemba
- Molecular Biophysics Program and Department of Biochemistry, University of Colorado, Boulder, Colorado
| | - Joseph J Falke
- Molecular Biophysics Program and Department of Biochemistry, University of Colorado, Boulder, Colorado.
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9
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Rathinaswamy MK, Fleming KD, Dalwadi U, Pardon E, Harris NJ, Yip CK, Steyaert J, Burke JE. HDX-MS-optimized approach to characterize nanobodies as tools for biochemical and structural studies of class IB phosphoinositide 3-kinases. Structure 2021; 29:1371-1381.e6. [PMID: 34348129 DOI: 10.1016/j.str.2021.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 06/07/2021] [Accepted: 07/15/2021] [Indexed: 10/20/2022]
Abstract
There is considerable interest in developing antibodies as modulators of signaling pathways. One of the most important signaling pathways in higher eukaryotes is the phosphoinositide 3-kinase (PI3K) pathway, which plays fundamental roles in growth, metabolism, and immunity. The class IB PI3K, PI3Kγ, is a heterodimeric complex composed of a catalytic p110γ subunit bound to a p101 or p84 regulatory subunit. PI3Kγ is a critical component in multiple immune signaling processes and is dependent on activation by Ras and G protein-coupled receptors (GPCRs) to mediate its cellular roles. Here we describe the rapid and efficient characterization of multiple PI3Kγ binding single-chain camelid nanobodies using hydrogen-deuterium exchange (HDX) mass spectrometry (MS) for structural and biochemical studies. We identify nanobodies that stimulated lipid kinase activity, block Ras activation, and specifically inhibited p101-mediated GPCR activation. Overall, our work reveals insight into PI3Kγ regulation and identifies sites that may be exploited for therapeutic development.
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Affiliation(s)
- Manoj K Rathinaswamy
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada
| | - Kaelin D Fleming
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada
| | - Udit Dalwadi
- Life Sciences Institute, Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Els Pardon
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium; VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Noah J Harris
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada
| | - Calvin K Yip
- Life Sciences Institute, Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium; VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - John E Burke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada; Life Sciences Institute, Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
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10
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Tremel S, Ohashi Y, Morado DR, Bertram J, Perisic O, Brandt LTL, von Wrisberg MK, Chen ZA, Maslen SL, Kovtun O, Skehel M, Rappsilber J, Lang K, Munro S, Briggs JAG, Williams RL. Structural basis for VPS34 kinase activation by Rab1 and Rab5 on membranes. Nat Commun 2021; 12:1564. [PMID: 33692360 PMCID: PMC7946940 DOI: 10.1038/s41467-021-21695-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 02/01/2021] [Indexed: 02/07/2023] Open
Abstract
The lipid phosphatidylinositol-3-phosphate (PI3P) is a regulator of two fundamental but distinct cellular processes, endocytosis and autophagy, so its generation needs to be under precise temporal and spatial control. PI3P is generated by two complexes that both contain the lipid kinase VPS34: complex II on endosomes (VPS34/VPS15/Beclin 1/UVRAG), and complex I on autophagosomes (VPS34/VPS15/Beclin 1/ATG14L). The endosomal GTPase Rab5 binds complex II, but the mechanism of VPS34 activation by Rab5 has remained elusive, and no GTPase is known to bind complex I. Here we show that Rab5a–GTP recruits endocytic complex II to membranes and activates it by binding between the VPS34 C2 and VPS15 WD40 domains. Electron cryotomography of complex II on Rab5a-decorated vesicles shows that the VPS34 kinase domain is released from inhibition by VPS15 and hovers over the lipid bilayer, poised for catalysis. We also show that the GTPase Rab1a, which is known to be involved in autophagy, recruits and activates the autophagy-specific complex I, but not complex II. Both Rabs bind to the same VPS34 interface but in a manner unique for each. These findings reveal how VPS34 complexes are activated on membranes by specific Rab GTPases and how they are recruited to unique cellular locations. The phosphatidylinositol-3-phosphate (PI3P) is generated by the lipid kinase VPS34, in the context of VPS34 complex I on autophagosomes or complex II on endosomes. Biochemical and structural analyses provide insights into the mechanism of both VPS34 complexes recruitment to and activation on membranes by specific Rab GTPases.
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Affiliation(s)
| | - Yohei Ohashi
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Dustin R Morado
- MRC Laboratory of Molecular Biology, Cambridge, UK.,Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden
| | | | - Olga Perisic
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | | | - Marie-Kristin von Wrisberg
- Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, Lab for Synthetic Biochemistry, Technical University of Munich, Institute for Advanced Study, TUM-IAS, Garching, Germany
| | - Zhuo A Chen
- Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
| | | | | | - Mark Skehel
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Juri Rappsilber
- Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany.,Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Kathrin Lang
- Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, Lab for Synthetic Biochemistry, Technical University of Munich, Institute for Advanced Study, TUM-IAS, Garching, Germany
| | - Sean Munro
- MRC Laboratory of Molecular Biology, Cambridge, UK.
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11
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Ohashi Y. Class III phosphatidylinositol 3-kinase complex I subunit NRBF2/Atg38 - from cell and structural biology to health and disease. Autophagy 2021; 17:3897-3907. [PMID: 33459128 PMCID: PMC8726667 DOI: 10.1080/15548627.2021.1872240] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Macroautophagy/autophagy is triggered by various starvation and stress conditions. The phospholipid phosphatidylinositol-3-phosphate (PtdIns3P) is essential for the formation of the autophagosome both in yeast and mammals. The class III phosphatidylinositol 3-kinase, PIK3C3C in humans or Vps34 in yeast, produces PtdIns3P by phosphorylating the 3'-OH position of phosphatidylinositol (PtdIns). In order to synthesize PtdIns3P for the initiation of autophagy, PIK3C3/Vps34 has a heterotetrameric core, the PIK3C3 complex I (hereafter complex I) composed of PIK3C3/Vps34, PIK3R4/Vps15, BECN1/Vps30, and ATG14/Atg14. A fifth component of complex I, NRBF2 in mammals and Atg38 in yeast, was found and has been characterized in the past decade. The field has been expanding from cell and structural biology to mouse model and cohort studies. Here I will summarize the structures and models of complex I binding NRBF2/Atg38, its intracellular roles, and its involvement in health and disease. Along with this expansion of the field, different conclusions have been drawn in several topics. I will clarify what has and has not been agreed, and what is to be clarified in the future.
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Affiliation(s)
- Yohei Ohashi
- Division of Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, UK
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