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Častorálová M, Sýs J, Prchal J, Pavlů A, Prokopová L, Briki Z, Hubálek M, Ruml T. A myristoyl switch at the plasma membrane triggers cleavage and oligomerization of Mason-Pfizer monkey virus matrix protein. eLife 2024; 13:e93489. [PMID: 38517277 PMCID: PMC11014724 DOI: 10.7554/elife.93489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 03/10/2024] [Indexed: 03/23/2024] Open
Abstract
For most retroviruses, including HIV, association with the plasma membrane (PM) promotes the assembly of immature particles, which occurs simultaneously with budding and maturation. In these viruses, maturation is initiated by oligomerization of polyprotein precursors. In contrast, several retroviruses, such as Mason-Pfizer monkey virus (M-PMV), assemble in the cytoplasm into immature particles that are transported across the PM. Therefore, protease activation and specific cleavage must not occur until the pre-assembled particle interacts with the PM. This interaction is triggered by a bipartite signal consisting of a cluster of basic residues in the matrix (MA) domain of Gag polyprotein and a myristoyl moiety N-terminally attached to MA. Here, we provide evidence that myristoyl exposure from the MA core and its insertion into the PM occurs in M-PMV. By a combination of experimental methods, we show that this results in a structural change at the C-terminus of MA allowing efficient cleavage of MA from the downstream region of Gag. This suggests that, in addition to the known effect of the myristoyl switch of HIV-1 MA on the multimerization state of Gag and particle assembly, the myristoyl switch may have a regulatory role in initiating sequential cleavage of M-PMV Gag in immature particles.
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Affiliation(s)
- Markéta Častorálová
- Department of Biochemistry and Microbiology, University of Chemistry and TechnologyPragueCzech Republic
| | - Jakub Sýs
- Department of Biochemistry and Microbiology, University of Chemistry and TechnologyPragueCzech Republic
- Institute of Organic Chemistry and Biochemistry of Czech Academy of SciencePragueCzech Republic
| | - Jan Prchal
- Department of Biochemistry and Microbiology, University of Chemistry and TechnologyPragueCzech Republic
| | - Anna Pavlů
- Department of Biochemistry and Microbiology, University of Chemistry and TechnologyPragueCzech Republic
| | - Lucie Prokopová
- Department of Biochemistry and Microbiology, University of Chemistry and TechnologyPragueCzech Republic
| | - Zina Briki
- Department of Biochemistry and Microbiology, University of Chemistry and TechnologyPragueCzech Republic
| | - Martin Hubálek
- Institute of Organic Chemistry and Biochemistry of Czech Academy of SciencePragueCzech Republic
| | - Tomas Ruml
- Department of Biochemistry and Microbiology, University of Chemistry and TechnologyPragueCzech Republic
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2
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Banerjee P, Qu K, Briggs JAG, Voth GA. Molecular dynamics simulations of HIV-1 matrix-membrane interactions at different stages of viral maturation. Biophys J 2024; 123:389-406. [PMID: 38196190 PMCID: PMC10870173 DOI: 10.1016/j.bpj.2024.01.006] [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: 09/25/2023] [Revised: 12/05/2023] [Accepted: 01/04/2024] [Indexed: 01/11/2024] Open
Abstract
Although the structural rearrangement of the membrane-bound matrix (MA) protein trimers upon HIV-1 maturation has been reported, the consequences of MA maturation on the MA-lipid interactions are not well understood. Long-timescale molecular dynamics simulations of the MA multimeric assemblies of immature and mature virus particles with our realistic asymmetric membrane model have explored MA-lipid interactions and lateral organization of lipids around MA complexes. The number of stable MA-phosphatidylserine and MA-phosphatidylinositol 4,5-bisphosphate (PIP2) interactions at the trimeric interface of the mature MA complex is observed to be greater compared to that of the immature MA complex. Our simulations identified an alternative PIP2-binding site in the immature MA complex where the multivalent headgroup of a PIP2 lipid with a greater negative charge binds to multiple basic amino acid residues such as ARG3 residues of both the MA monomers at the trimeric interface and highly basic region (HBR) residues (LYS29, LYS31) of one of the MA monomers. Our enhanced sampling simulations have explored the conformational space of phospholipids at different binding sites of the trimer-trimer interface of MA complexes that are not accessible by conventional unbiased molecular dynamics. Unlike the immature MA complex, the 2' acyl tail of two PIP2 lipids at the trimeric interface of the mature MA complex is observed to sample stable binding pockets of MA consisting of helix-4 residues. Together, our results provide molecular-level insights into the interactions of MA trimeric complexes with membrane and different lipid conformations at the specific binding sites of MA protein before and after viral maturation.
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Affiliation(s)
- Puja Banerjee
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois
| | - Kun Qu
- Infectious Diseases Translational Research Programme, Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - John A G Briggs
- Department of Cell and Virus Structure, Max Planck Institute of Biochemistry, Planegg, Germany
| | - Gregory A Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois.
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3
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Kang H, Kang T, Jackson L, Murphy A, Nitta T. Evidence for Involvement of ADP-Ribosylation Factor 6 in Intracellular Trafficking and Release of Murine Leukemia Virus Gag. Cells 2024; 13:270. [PMID: 38334661 PMCID: PMC10854678 DOI: 10.3390/cells13030270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 01/29/2024] [Accepted: 01/29/2024] [Indexed: 02/10/2024] Open
Abstract
Murine leukemia viruses (MuLVs) are simple retroviruses that cause several diseases in mice. Retroviruses encode three basic genes: gag, pol, and env. Gag is translated as a polyprotein and moves to assembly sites where viral particles are shaped by cleavage of poly-Gag. Viral release depends on the intracellular trafficking of viral proteins, which is determined by both viral and cellular factors. ADP-ribosylation factor 6 (Arf6) is a small GTPase that regulates vesicular trafficking and recycling of different types of cargo in cells. Arf6 also activates phospholipase D (PLD) and phosphatidylinositol-4-phosphate 5-kinase (PIP5K) and produces phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2). We investigated how Arf6 affected MuLV release with a constitutively active form of Arf6, Arf6Q67L. Expression of Arf6Q67L impaired Gag release by accumulating Gag at PI(4,5)P2-enriched compartments in the cytoplasm. Treatment of the inhibitors for PLD and PIP5K impaired or recovered MuLV Gag release in the cells expressing GFP (control) and Arf6Q67L, implying that regulation of PI(4,5)P2 through PLD and PIP5K affected MuLV release. Interference with the phosphoinositide 3-kinases, mammalian target of rapamycin (mTOR) pathway, and vacuolar-type ATPase activities showed further impairment of Gag release from the cells expressing Arf6Q67L. In contrast, mTOR inhibition increased Gag release in the control cells. The proteasome inhibitors reduced viral release in the cells regardless of Arf6Q67L expression. These data outline the differences in MuLV release under the controlled and overactivated Arf6 conditions and provide new insight into pathways for MuLV release.
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Affiliation(s)
- Hyokyun Kang
- Department of Biology, Savannah State University, Savannah, GA 31404, USA; (H.K.); (T.K.); (L.J.); (A.M.)
| | - Taekwon Kang
- Department of Biology, Savannah State University, Savannah, GA 31404, USA; (H.K.); (T.K.); (L.J.); (A.M.)
| | - Lauryn Jackson
- Department of Biology, Savannah State University, Savannah, GA 31404, USA; (H.K.); (T.K.); (L.J.); (A.M.)
| | - Amaiya Murphy
- Department of Biology, Savannah State University, Savannah, GA 31404, USA; (H.K.); (T.K.); (L.J.); (A.M.)
| | - Takayuki Nitta
- Department of Biology, Savannah State University, Savannah, GA 31404, USA; (H.K.); (T.K.); (L.J.); (A.M.)
- Department of Molecular Biology and Biochemistry, Cancer Research Institute, University of California, Irvine, CA 92697, USA
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Maity D, Singh D, Bandhu A. Mce1R of Mycobacterium tuberculosis prefers long-chain fatty acids as specific ligands: a computational study. Mol Divers 2023; 27:2523-2543. [PMID: 36385433 DOI: 10.1007/s11030-022-10566-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Accepted: 11/04/2022] [Indexed: 11/17/2022]
Abstract
The mce1 operon of Mycobacterium tuberculosis, which codes the Mce1 transporter, facilitates the transport of fatty acids. Fatty acids are one of the major sources for carbon and energy for the pathogen during its intracellular survival and pathogenicity. The mce1 operon is transcriptionally regulated by Mce1R, a VanR-type regulator, which could bind specific ligands and control the expression of the mce1 operon accordingly. This work reports computational identification of Mce1R-specific ligands. Initially by employing cavity similarity search algorithm by the ProBis server, the cavities of the proteins similar to that of Mce1R and the bound ligands were identified from which fatty acids were selected as the potential ligands. From the earlier-generated monomeric structure, the dimeric structure of Mce1R was then modeled by the GalaxyHomomer server and validated computationally to use in molecular docking and molecular dynamics simulation analysis. The fatty acid ligands were found to dock within the cavity of Mce1R and the docked complexes were subjected to molecular dynamics simulation to explore their stabilities and other dynamic properties. The data suggest that Mce1R preferably binds to long-chain fatty acids and undergoes distinct structural changes upon binding.
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Affiliation(s)
- Dipanwita Maity
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, 506004, India
| | - Dheeraj Singh
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, 506004, India
| | - Amitava Bandhu
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, 506004, India.
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5
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Ghanam RH, Eastep GN, Saad JS. Structural Insights into the Mechanism of HIV-1 Tat Secretion from the Plasma Membrane. J Mol Biol 2023; 435:167880. [PMID: 36370804 PMCID: PMC9822876 DOI: 10.1016/j.jmb.2022.167880] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/27/2022] [Accepted: 11/04/2022] [Indexed: 11/11/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) trans-activator of transcription (Tat) is a small, intrinsically disordered basic protein that plays diverse roles in the HIV-1 replication cycle, including promotion of efficient viral RNA transcription. Tat is released by infected cells and subsequently absorbed by healthy cells, thereby contributing to HIV-1 pathogenesis including HIV-associated neurocognitive disorder. It has been shown that, in HIV-1-infected primary CD4 T-cells, Tat accumulates at the plasma membrane (PM) for secretion, a mechanism mediated by phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). However, the structural basis for Tat interaction with the PM and thereby secretion is lacking. Herein, we employed NMR and biophysical methods to characterize Tat86 (86 amino acids) interactions with PI(4,5)P2 and lipid nanodiscs (NDs). Our data revealed that Arg49, Lys50 and Lys51 (RKK motif) constitute the PI(4,5)P2 binding site, that Tat86 interaction with lipid NDs is dependent on PI(4,5)P2 and phosphatidylserine (PS), and that the arginine-rich motif (RRQRRR) preferentially interacts with PS. Furthermore, we show that Trp11, previously implicated in Tat secretion, penetrates deeply in the membrane; substitution of Trp11 severely reduced Tat86 interaction with membranes. Deletion of the entire highly basic region and Trp11 completely abolished Tat86 binding to lipid NDs. Our data support a mechanism by which HIV-1 Tat secretion from the PM is mediated by a tripartite signal consisting of binding of the RKK motif to PI(4,5)P2, arginine-rich motif to PS, and penetration of Trp11 in the membrane. Altogether, these findings provide new insights into the molecular requirements for Tat binding to membranes during secretion.
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Affiliation(s)
- Ruba H Ghanam
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Gunnar N Eastep
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
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6
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Herrmann D, Hanson HM, Zhou LW, Addabbo R, Willkomm NA, Angert I, Mueller JD, Mansky LM, Saad JS. Molecular Determinants of Human T-cell Leukemia Virus Type 1 Gag Targeting to the Plasma Membrane for Assembly. J Mol Biol 2022; 434:167609. [PMID: 35490898 PMCID: PMC10557380 DOI: 10.1016/j.jmb.2022.167609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/20/2022] [Accepted: 04/23/2022] [Indexed: 01/10/2023]
Abstract
Assembly of human T-cell leukemia virus type 1 (HTLV-1) particles is initiated by the trafficking of virally encoded Gag polyproteins to the inner leaflet of the plasma membrane (PM). Gag-PM interactions are mediated by the matrix (MA) domain, which contains a myristoyl group (myr) and a basic patch formed by lysine and arginine residues. For many retroviruses, Gag-PM interactions are mediated by phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]; however, previous studies suggested that HTLV-1 Gag-PM interactions and therefore virus assembly are less dependent on PI(4,5)P2. We have recently shown that PI(4,5)P2 binds directly to HTLV-1 unmyristoylated MA [myr(-)MA] and that myr(-)MA binding to membranes is significantly enhanced by inclusion of phosphatidylserine (PS) and PI(4,5)P2. Herein, we employed structural, biophysical, biochemical, mutagenesis, and cell-based assays to identify residues involved in MA-membrane interactions. Our data revealed that the lysine-rich motif (Lys47, Lys48, and Lys51) constitutes the primary PI(4,5)P2-binding site. Furthermore, we show that arginine residues 3, 7, 14 and 17 located in the unstructured N-terminus are essential for MA binding to membranes containing PS and/or PI(4,5)P2. Substitution of lysine and arginine residues severely attenuated virus-like particle production, but only the lysine residues could be clearly correlated with reduced PM binding. These results support a mechanism by which HTLV-1 Gag targeting to the PM is mediated by a trio engagement of the myr group, Arg-rich and Lys-rich motifs. These findings advance our understanding of a key step in retroviral particle assembly.
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Affiliation(s)
- Dominik Herrmann
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Heather M Hanson
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, United States
| | - Lynne W Zhou
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Rayna Addabbo
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, United States; School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, United States
| | - Nora A Willkomm
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, United States
| | - Isaac Angert
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, United States; School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, United States
| | - Joachim D Mueller
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, United States; School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, United States
| | - Louis M Mansky
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, United States.
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
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7
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Atomic view of the HIV-1 matrix lattice; implications on virus assembly and envelope incorporation. Proc Natl Acad Sci U S A 2022; 119:e2200794119. [PMID: 35658080 PMCID: PMC9191676 DOI: 10.1073/pnas.2200794119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
SignificanceThe assembly of immature HIV-1 particles is initiated by targeting of the Gag polyproteins to the plasma membrane (PM). Gag binding to the PM is mediated by the N-terminally myristoylated matrix (myrMA) domain. Formation of a Gag lattice on the PM is obligatory for the assembly of immature HIV-1 and envelope (Env) incorporation. The structure of the myrMA lattice presented here provided insights on the molecular factors that stabilize the lattice and hence favor Env incorporation. Our data support a mechanism for Gag binding to the PM during the assembly of immature particles and upon maturation. These findings advance our understanding of a critical step in HIV-1 assembly.
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8
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Ciftci H, Tateishi H, Koiwai K, Koga R, Anraku K, Monde K, Dağ Ç, Destan E, Yuksel B, Ayan E, Yildirim G, Yigin M, Ertem FB, Shafiei A, Guven O, Besler SO, Sierra RG, Yoon CH, Su Z, Liang M, Acar B, Haliloglu T, Otsuka M, Yumoto F, Fujita M, Senda T, DeMirci H. Structural insight into host plasma membrane association and assembly of HIV-1 matrix protein. Sci Rep 2021; 11:15819. [PMID: 34349176 PMCID: PMC8339130 DOI: 10.1038/s41598-021-95236-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 07/15/2021] [Indexed: 11/25/2022] Open
Abstract
Oligomerization of Pr55Gag is a critical step of the late stage of the HIV life cycle. It has been known that the binding of IP6, an abundant endogenous cyclitol molecule at the MA domain, has been linked to the oligomerization of Pr55Gag. However, the exact binding site of IP6 on MA remains unknown and the structural details of this interaction are missing. Here, we present three high-resolution crystal structures of the MA domain in complex with IP6 molecules to reveal its binding mode. Additionally, extensive Differential Scanning Fluorimetry analysis combined with cryo- and ambient-temperature X-ray crystallography and GNM-based transfer entropy calculations identify the key residues that participate in IP6 binding. Our data provide novel insights about the multilayered HIV-1 virion assembly process that involves the interplay of IP6 with PIP2, a phosphoinositide essential for the binding of Pr55Gag to membrane. IP6 and PIP2 have neighboring alternate binding sites within the same highly basic region (residues 18-33). This indicates that IP6 and PIP2 bindings are not mutually exclusive and may play a key role in coordinating virion particles' membrane localization. Based on our three different IP6-MA complex crystal structures, we propose a new model that involves IP6 coordination of the oligomerization of outer MA and inner CA domain's 2D layers during assembly and budding.
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Affiliation(s)
- Halilibrahim Ciftci
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto, 862-0973, Japan
- Department of Drug Discovery, Science Farm Ltd, Kumamoto, 862-0976, Japan
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Hiroshi Tateishi
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto, 862-0973, Japan
| | - Kotaro Koiwai
- Structural Biology Research Center, Institute of Materials Structure Science, KEK/High Energy Accelerator Research Organization, Tsukuba, Ibaraki, 305-0801, Japan
| | - Ryoko Koga
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto, 862-0973, Japan
| | - Kensaku Anraku
- Department of Medical Technology, Kumamoto Health Science University, Kumamoto, 861-5598, Japan
| | - Kazuaki Monde
- Department of Microbiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, 860-8556, Japan
| | - Çağdaş Dağ
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
- Department of Molecular Biology and Genetics, Koc University, 34450, Istanbul, Turkey
| | - Ebru Destan
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Busra Yuksel
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Esra Ayan
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Gunseli Yildirim
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Merve Yigin
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - F Betul Ertem
- Department of Molecular Biology and Genetics, Koc University, 34450, Istanbul, Turkey
| | - Alaleh Shafiei
- Department of Molecular Biology and Genetics, Koc University, 34450, Istanbul, Turkey
| | - Omur Guven
- Department of Molecular Biology and Genetics, Koc University, 34450, Istanbul, Turkey
| | - Sabri O Besler
- Department of Molecular Biology and Genetics, Koc University, 34450, Istanbul, Turkey
| | - Raymond G Sierra
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Chun Hong Yoon
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Zhen Su
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Mengling Liang
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Burcin Acar
- Polymer Research Center, Bogazici University, 34342, Istanbul, Turkey
| | - Turkan Haliloglu
- Department of Chemical Engineering, Bogazici University, 34342, Istanbul, Turkey
- Polymer Research Center, Bogazici University, 34342, Istanbul, Turkey
| | - Masami Otsuka
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto, 862-0973, Japan
- Department of Drug Discovery, Science Farm Ltd, Kumamoto, 862-0976, Japan
| | - Fumiaki Yumoto
- Structural Biology Research Center, Institute of Materials Structure Science, KEK/High Energy Accelerator Research Organization, Tsukuba, Ibaraki, 305-0801, Japan
| | - Mikako Fujita
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto, 862-0973, Japan.
| | - Toshiya Senda
- Structural Biology Research Center, Institute of Materials Structure Science, KEK/High Energy Accelerator Research Organization, Tsukuba, Ibaraki, 305-0801, Japan.
- School of High Energy Accelerator Science, SOKENDAI University, Tsukuba, Ibaraki, 305-0801, Japan.
- Faculty of Pure and Applied Sciences, University of Tsukuba, Ibaraki, 305-8571, Japan.
| | - Hasan DeMirci
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
- Department of Molecular Biology and Genetics, Koc University, 34450, Istanbul, Turkey.
- Koc University Isbank Center for Infectious Diseases (KUISCID), 34450, Istanbul, Turkey.
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9
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Herrmann D, Zhou LW, Hanson HM, Willkomm NA, Mansky LM, Saad JS. Structural Insights into the Mechanism of Human T-cell Leukemia Virus Type 1 Gag Targeting to the Plasma Membrane for Assembly. J Mol Biol 2021; 433:167161. [PMID: 34298060 PMCID: PMC8453114 DOI: 10.1016/j.jmb.2021.167161] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 07/10/2021] [Accepted: 07/12/2021] [Indexed: 01/10/2023]
Abstract
Retroviral Gag targeting to the plasma membrane (PM) for assembly is mediated by the N-terminal matrix (MA) domain. For many retroviruses, Gag-PM interaction is dependent on phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). However, it has been shown that for human T-cell leukemia virus type 1 (HTLV-1), Gag binding to membranes is less dependent on PI(4,5)P2 than HIV-1, suggesting that other factors may modulate Gag assembly. To elucidate the mechanism by which HTLV-1 Gag binds to the PM, we employed NMR techniques to determine the structure of unmyristoylated MA (myr(-)MA) and to characterize its interactions with lipids and liposomes. The MA structure consists of four α-helices and unstructured N- and C-termini. We show that myr(-)MA binds to PI(4,5)P2 via the polar head and that binding to inositol phosphates (IPs) is significantly enhanced by increasing the number of phosphate groups on the inositol ring, indicating that the MA-IP binding is governed by charge-charge interactions. The IP binding site was mapped to a well-defined basic patch formed by lysine and arginine residues. Using an NMR-based liposome binding assay, we show that PI(4,5)P2and phosphatidylserine enhance myr(-)MA binding in a synergistic fashion. Confocal microscopy data revealed formation of puncta on the PM of Gag expressing cells. However, G2A-Gag mutant, lacking myristoylation, is diffuse and cytoplasmic. These results suggest that although myr(-)MA binds to membranes, myristoylation appears to be key for formation of HTLV-1 Gag puncta on the PM. Altogether, these findings advance our understanding of a key mechanism in retroviral assembly.
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Affiliation(s)
- Dominik Herrmann
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Lynne W Zhou
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Heather M Hanson
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - Nora A Willkomm
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - Louis M Mansky
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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10
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Eastep GN, Ghanam RH, Green TJ, Saad JS. Structural characterization of HIV-1 matrix mutants implicated in envelope incorporation. J Biol Chem 2021; 296:100321. [PMID: 33485964 PMCID: PMC7952133 DOI: 10.1016/j.jbc.2021.100321] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 01/05/2021] [Accepted: 01/20/2021] [Indexed: 11/28/2022] Open
Abstract
During the late phase of HIV-1 infection, viral Gag polyproteins are targeted to the plasma membrane (PM) for assembly. Gag localization at the PM is a prerequisite for the incorporation of the envelope protein (Env) into budding particles. Gag assembly and Env incorporation are mediated by the N-terminal myristoylated matrix (MA) domain of Gag. Nonconservative mutations in the trimer interface of MA (A45E, T70R, and L75G) were found to impair Env incorporation and infectivity, leading to the hypothesis that MA trimerization is an obligatory step for Env incorporation. Conversely, Env incorporation can be rescued by a compensatory mutation in the MA trimer interface (Q63R). The impact of these MA mutations on the structure and trimerization properties of MA is not known. In this study, we employed NMR spectroscopy, X-ray crystallography, and sedimentation techniques to characterize the structure and trimerization properties of HIV-1 MA A45E, Q63R, T70R, and L75G mutant proteins. NMR data revealed that these point mutations did not alter the overall structure and folding of MA but caused minor structural perturbations in the trimer interface. Analytical ultracentrifugation data indicated that mutations had a minimal effect on the MA monomer–trimer equilibrium. The high-resolution X-ray structure of the unmyristoylated MA Q63R protein revealed hydrogen bonding between the side chains of adjacent Arg-63 and Ser-67 on neighboring MA molecules, providing the first structural evidence for an additional intermolecular interaction in the trimer interface. These findings advance our knowledge of the interplay of MA trimerization and Env incorporation into HIV-1 particles.
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Affiliation(s)
- Gunnar N Eastep
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Ruba H Ghanam
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Todd J Green
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
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11
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Boyd PS, Brown JB, Brown JD, Catazaro J, Chaudry I, Ding P, Dong X, Marchant J, O’Hern CT, Singh K, Swanson C, Summers MF, Yasin S. NMR Studies of Retroviral Genome Packaging. Viruses 2020; 12:v12101115. [PMID: 33008123 PMCID: PMC7599994 DOI: 10.3390/v12101115] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/18/2020] [Accepted: 09/26/2020] [Indexed: 12/03/2022] Open
Abstract
Nearly all retroviruses selectively package two copies of their unspliced RNA genomes from a cellular milieu that contains a substantial excess of non-viral and spliced viral RNAs. Over the past four decades, combinations of genetic experiments, phylogenetic analyses, nucleotide accessibility mapping, in silico RNA structure predictions, and biophysical experiments were employed to understand how retroviral genomes are selected for packaging. Genetic studies provided early clues regarding the protein and RNA elements required for packaging, and nucleotide accessibility mapping experiments provided insights into the secondary structures of functionally important elements in the genome. Three-dimensional structural determinants of packaging were primarily derived by nuclear magnetic resonance (NMR) spectroscopy. A key advantage of NMR, relative to other methods for determining biomolecular structure (such as X-ray crystallography), is that it is well suited for studies of conformationally dynamic and heterogeneous systems—a hallmark of the retrovirus packaging machinery. Here, we review advances in understanding of the structures, dynamics, and interactions of the proteins and RNA elements involved in retroviral genome selection and packaging that are facilitated by NMR.
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12
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Rendezvous at Plasma Membrane: Cellular Lipids and tRNA Set up Sites of HIV-1 Particle Assembly and Incorporation of Host Transmembrane Proteins. Viruses 2020; 12:v12080842. [PMID: 32752131 PMCID: PMC7472227 DOI: 10.3390/v12080842] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 07/20/2020] [Accepted: 07/24/2020] [Indexed: 12/28/2022] Open
Abstract
The HIV-1 structural polyprotein Gag drives the virus particle assembly specifically at the plasma membrane (PM). During this process, the nascent virion incorporates specific subsets of cellular lipids and host membrane proteins, in addition to viral glycoproteins and viral genomic RNA. Gag binding to the PM is regulated by cellular factors, including PM-specific phospholipid PI(4,5)P2 and tRNAs, both of which bind the highly basic region in the matrix domain of Gag. In this article, we review our current understanding of the roles played by cellular lipids and tRNAs in specific localization of HIV-1 Gag to the PM. Furthermore, we examine the effects of PM-bound Gag on the organization of the PM bilayer and discuss how the reorganization of the PM at the virus assembly site potentially contributes to the enrichment of host transmembrane proteins in the HIV-1 particle. Since some of these host transmembrane proteins alter release, attachment, or infectivity of the nascent virions, the mechanism of Gag targeting to the PM and the nature of virus assembly sites have major implications in virus spread.
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13
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Brown JB, Summers HR, Brown LA, Marchant J, Canova PN, O'Hern CT, Abbott ST, Nyaunu C, Maxwell S, Johnson T, Moser MB, Ablan SD, Carter H, Freed EO, Summers MF. Structural and Mechanistic Studies of the Rare Myristoylation Signal of the Feline Immunodeficiency Virus. J Mol Biol 2020; 432:4076-4091. [PMID: 32442659 PMCID: PMC7316625 DOI: 10.1016/j.jmb.2020.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/13/2020] [Accepted: 05/14/2020] [Indexed: 10/24/2022]
Abstract
All retroviruses encode a Gag polyprotein containing an N-terminal matrix domain (MA) that anchors Gag to the plasma membrane and recruits envelope glycoproteins to virus assembly sites. Membrane binding by the Gag protein of HIV-1 and most other lentiviruses is dependent on N-terminal myristoylation of MA by host N-myristoyltransferase enzymes (NMTs), which recognize a six-residue "myristoylation signal" with consensus sequence: M1GXXX[ST]. For unknown reasons, the feline immunodeficiency virus (FIV), which infects both domestic and wild cats, encodes a non-consensus myristoylation sequence not utilized by its host or by other mammals (most commonly: M1GNGQG). To explore the evolutionary basis for this sequence, we compared the structure, dynamics, and myristoylation properties of native FIV MA with a mutant protein containing a consensus feline myristoylation motif (MANOS) and examined the impact of MA mutations on virus assembly and ability to support spreading infection. Unexpectedly, myristoylation efficiency of MANOS in Escherichia coli by co-expressed mammalian NMT was reduced by ~70% compared to the wild-type protein. NMR studies revealed that residues of the N-terminal myristoylation signal are fully exposed and mobile in the native protein but partially sequestered in the MANOS chimera, suggesting that the unusual FIV sequence is conserved to promote exposure and efficient myristoylation of the MA N terminus. In contrast, virus assembly studies indicate that the MANOS mutation does not affect virus assembly, but does prevent virus spread, in feline kidney cells. Our findings indicate that residues of the FIV myristoylation sequence play roles in replication beyond NMT recognition and Gag-membrane binding.
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Affiliation(s)
- Janae B Brown
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Holly R Summers
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Lola A Brown
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Jan Marchant
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Paige N Canova
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Colin T O'Hern
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Sophia T Abbott
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Constance Nyaunu
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Simon Maxwell
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Talayah Johnson
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Morgan B Moser
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Sherimay D Ablan
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, National Cancer Institute at Fredrick, Fredrick, MD 21702-1201, USA
| | - Hannah Carter
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, National Cancer Institute at Fredrick, Fredrick, MD 21702-1201, USA
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, National Cancer Institute at Fredrick, Fredrick, MD 21702-1201, USA.
| | - Michael F Summers
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA.
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14
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Murphy RE, Saad JS. The Interplay between HIV-1 Gag Binding to the Plasma Membrane and Env Incorporation. Viruses 2020; 12:E548. [PMID: 32429351 PMCID: PMC7291237 DOI: 10.3390/v12050548] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 05/14/2020] [Accepted: 05/14/2020] [Indexed: 12/21/2022] Open
Abstract
Advancement in drug therapies and patient care have drastically improved the mortality rates of HIV-1 infected individuals. Many of these therapies were developed or improved upon by using structure-based techniques, which underscore the importance of understanding essential mechanisms in the replication cycle of HIV-1 at the structural level. One such process which remains poorly understood is the incorporation of the envelope glycoprotein (Env) into budding virus particles. Assembly of HIV particles is initiated by targeting of the Gag polyproteins to the inner leaflet of the plasma membrane (PM), a process mediated by the N-terminally myristoylated matrix (MA) domain and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). There is strong evidence that formation of the Gag lattice on the PM is a prerequisite for the incorporation of Env into budding particles. It is also suggested that Env incorporation is mediated by an interaction between its cytoplasmic tail (gp41CT) and the MA domain of Gag. In this review, we highlight the latest developments and current efforts to understand the interplay between gp41CT, MA, and the membrane during assembly. Elucidation of the molecular determinants of Gag-Env-membrane interactions may help in the development of new antiviral therapeutic agents that inhibit particle assembly, Env incorporation and ultimately virus production.
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Affiliation(s)
| | - Jamil S. Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA;
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15
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Junková P, Pleskot R, Prchal J, Sýs J, Ruml T. Differences and commonalities in plasma membrane recruitment of the two morphogenetically distinct retroviruses HIV-1 and MMTV. J Biol Chem 2020; 295:8819-8833. [PMID: 32385109 DOI: 10.1074/jbc.ra119.011991] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 05/05/2020] [Indexed: 11/06/2022] Open
Abstract
Retroviral Gag polyproteins are targeted to the inner leaflet of the plasma membrane through their N-terminal matrix (MA) domain. Because retroviruses of different morphogenetic types assemble their immature particles in distinct regions of the host cell, the mechanism of MA-mediated plasma membrane targeting differs among distinct retroviral morphogenetic types. Here, we focused on possible mechanistic differences of the MA-mediated plasma membrane targeting of the B-type mouse mammary tumor virus (MMTV) and C-type HIV-1, which assemble in the cytoplasm and at the plasma membrane, respectively. Molecular dynamics simulations, together with surface mapping, indicated that, similarly to HIV-1, MMTV uses a myristic switch to anchor the MA to the membrane and electrostatically interacts with phosphatidylinositol 4,5-bisphosphate to stabilize MA orientation. We observed that the affinity of MMTV MA to the membrane is lower than that of HIV-1 MA, possibly related to their different topologies and the number of basic residues in the highly basic MA region. The latter probably reflects the requirement of C-type retroviruses for tighter membrane binding, essential for assembly, unlike for D/B-type retroviruses, which assemble in the cytoplasm. A comparison of the membrane topology of the HIV-1 MA, using the surface-mapping method and molecular dynamics simulations, revealed that the residues at the HIV-1 MA C terminus help stabilize protein-protein interactions within the HIV-1 MA lattice at the plasma membrane. In summary, HIV-1 and MMTV share common features such as membrane binding of the MA via hydrophobic interactions and exhibit several differences, including lower membrane affinity of MMTV MA.
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Affiliation(s)
- Petra Junková
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Czech Republic; Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Roman Pleskot
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium; VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Jan Prchal
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Czech Republic
| | - Jakub Sýs
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Czech Republic
| | - Tomáš Ruml
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Czech Republic.
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16
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Angert I, Karuka SR, Hennen J, Chen Y, Albanesi JP, Mansky LM, Mueller JD. Sensitive Detection of Protein Binding to the Plasma Membrane with Dual-Color Z-Scan Fluorescence. Biophys J 2020; 118:281-293. [PMID: 31870539 DOI: 10.1016/j.bpj.2019.12.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 11/22/2019] [Accepted: 12/03/2019] [Indexed: 11/25/2022] Open
Abstract
Delicate and transitory protein engagement at the plasma membrane (PM) is crucial to a broad range of cellular functions, including cell motility, signal transduction, and virus replication. Here, we describe a dual-color (DC) extension of the fluorescence z-scan technique, which has proven successful for quantification of peripheral membrane protein binding to the PM in living cells. We demonstrate that the coexpression of a second, distinctly colored fluorescent protein provides a soluble reference species that delineates the extent of the cell cytoplasm and lowers the detection threshold of z-scan PM-binding measurements by an order of magnitude. DC z-scan generates an intensity profile for each detection channel that contains information on the axial distribution of the peripheral membrane and reference protein. Fit models for DC z-scan are developed and verified using simple model systems. Next, we apply the quantitative DC z-scan technique to investigate the binding of two peripheral membrane protein systems for which previous z-scan studies failed to detect binding: human immunodeficiency virus type 1 (HIV-1) matrix (MA) protein and lipidation-deficient mutants of the fibroblast growth factor receptor substrate 2α. Our findings show that these mutations severely disrupt PM association of fibroblast growth factor receptor substrate 2α but do not eliminate it. We further detected binding of HIV-1 MA to the PM using DC z-scan. Interestingly, our data indicate that HIV-1 MA binds cooperatively to the PM with a dissociation coefficient of Kd ∼16 μM and Hill coefficient of n ∼2.
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Affiliation(s)
- Isaac Angert
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota
| | | | - Jared Hennen
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota
| | - Yan Chen
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota; Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota
| | - Joseph P Albanesi
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Louis M Mansky
- Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota; Division of Basic Sciences, University of Minnesota, Minneapolis, Minnesota; School of Dentistry, University of Minnesota, Minneapolis, Minnesota
| | - Joachim D Mueller
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota; Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota; Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota.
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17
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Murphy RE, Samal AB, Vlach J, Mas V, Prevelige PE, Saad JS. Structural and biophysical characterizations of HIV-1 matrix trimer binding to lipid nanodiscs shed light on virus assembly. J Biol Chem 2019; 294:18600-18612. [PMID: 31640987 PMCID: PMC6901326 DOI: 10.1074/jbc.ra119.010997] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 10/16/2019] [Indexed: 12/17/2022] Open
Abstract
During the late phase of the HIV-1 replication cycle, the viral Gag polyproteins are targeted to the plasma membrane for assembly. The Gag-membrane interaction is mediated by binding of Gag's N-terminal myristoylated matrix (MA) domain to phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). The viral envelope (Env) glycoprotein is then recruited to the assembly sites and incorporated into budding particles. Evidence suggests that Env incorporation is mediated by interactions between Gag's MA domain and the cytoplasmic tail of the gp41 subunit of Env (gp41CT). MA trimerization appears to be an obligatory step for this interaction. Insufficient production of a recombinant MA trimer and unavailability of a biologically relevant membrane system have been barriers to detailed structural and biophysical characterization of the putative MA-gp41CT-membrane interactions. Here, we engineered a stable recombinant HIV-1 MA trimer construct by fusing a foldon domain (FD) of phage T4 fibritin to the MA C terminus. Results from NMR experiments confirmed that the FD attachment does not adversely alter the MA structure. Employing hydrogen-deuterium exchange MS, we identified an MA-MA interface in the MA trimer that is implicated in Gag assembly and Env incorporation. Utilizing lipid nanodiscs as a membrane mimetic, we show that the MA trimer binds to membranes 30-fold tighter than does the MA monomer and that incorporation of PI(4,5)P2 and phosphatidylserine enhances the binding of MA to nanodiscs. These findings advance our understanding of a fundamental mechanism in HIV-1 assembly and provide a template for investigating the interaction of MA with gp41CT.
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Affiliation(s)
- R Elliot Murphy
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Alexandra B Samal
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Jiri Vlach
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Vicente Mas
- Centro Nacional de Microbiología and CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Peter E Prevelige
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294.
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18
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Watanabe SM, Medina GN, Eastep GN, Ghanam RH, Vlach J, Saad JS, Carter CA. The matrix domain of the Gag protein from avian sarcoma virus contains a PI(4,5)P 2-binding site that targets Gag to the cell periphery. J Biol Chem 2018; 293:18841-18853. [PMID: 30309982 DOI: 10.1074/jbc.ra118.003947] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 09/28/2018] [Indexed: 01/08/2023] Open
Abstract
The Gag protein of avian sarcoma virus (ASV) lacks an N-myristoyl (myr) group, but contains structural domains similar to those of HIV-1 Gag. Similarly to HIV-1, ASV Gag accumulates on the plasma membrane (PM) before egress; however, it is unclear whether the phospholipid PI(4,5)P2 binds directly to the matrix (MA) domain of ASV Gag, as is the case for HIV-1 Gag. Moreover, the role of PI(4,5)P2 in ASV Gag localization and budding has been controversial. Here, we report that substitution of residues that define the PI(4,5)P2-binding site in the ASV MA domain (reported in an accompanying paper) interfere with Gag localization to the cell periphery and inhibit the production of virus-like particles (VLPs). We show that co-expression of Sprouty2 (Spry2) or the pleckstrin homology domain of phospholipase Cδ (PH-PLC), two proteins that bind PI(4,5)P2, affects ASV Gag trafficking to the PM and budding. Replacement of the N-terminal 32 residues of HIV-1 MA, which encode its N-terminal myr signal and its PI(4,5)P2-binding site, with the structurally equivalent N-terminal 24 residues of ASV MA created a chimera that localized at the PM and produced VLPs. In contrast, the homologous PI(4,5)P2-binding signal in ASV MA could target HIV-1 Gag to the PM when substituted, but did not support budding. Collectively, these findings reveal a basic patch in both ASV and HIV-1 Gag capable of mediating PM binding and budding for ASV but not for HIV-1 Gag. We conclude that PI(4,5)P2 is a strong determinant of ASV Gag targeting to the PM and budding.
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Affiliation(s)
- Susan M Watanabe
- From the Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794 and
| | - Gisselle N Medina
- From the Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794 and
| | - Gunnar N Eastep
- the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Ruba H Ghanam
- the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Jiri Vlach
- the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Jamil S Saad
- the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Carol A Carter
- From the Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794 and
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19
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Vlach J, Eastep GN, Ghanam RH, Watanabe SM, Carter CA, Saad JS. Structural basis for targeting avian sarcoma virus Gag polyprotein to the plasma membrane for virus assembly. J Biol Chem 2018; 293:18828-18840. [PMID: 30309983 DOI: 10.1074/jbc.ra118.003944] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 09/17/2018] [Indexed: 01/30/2023] Open
Abstract
For most retroviruses, including HIV-1, binding of the Gag polyprotein to the plasma membrane (PM) is mediated by interactions between Gag's N-terminal myristoylated matrix (MA) domain and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) in the PM. The Gag protein of avian sarcoma virus (ASV) lacks the N-myristoylation signal but contains structural domains having functions similar to those of HIV-1 Gag. The molecular mechanism by which ASV Gag binds to the PM is incompletely understood. Here, we employed NMR techniques to elucidate the molecular determinants of the membrane-binding domain of ASV MA (MA87) to lipids and liposomes. We report that MA87 binds to the polar head of phosphoinositides such as PI(4,5)P2 We found that MA87 binding to inositol phosphates (IPs) is significantly enhanced by increasing the number of phosphate groups, indicating that the MA87-IP binding is governed by charge-charge interactions. Using a sensitive NMR-based liposome-binding assay, we show that binding of MA87 to liposomes is enhanced by incorporation of PI(4,5)P2 and phosphatidylserine. We also show that membrane binding is mediated by a basic surface formed by Lys-6, Lys-13, Lys-23, and Lys-24. Substitution of these residues to glutamate abolished binding of MA87 to both IPs and liposomes. In an accompanying paper, we further report that mutation of these lysine residues diminishes Gag assembly on the PM and inhibits ASV particle release. These findings provide a molecular basis for ASV Gag binding to the inner leaflet of the PM and advance our understanding of the basic mechanisms of retroviral assembly.
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Affiliation(s)
- Jiri Vlach
- From the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
| | - Gunnar N Eastep
- From the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
| | - Ruba H Ghanam
- From the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
| | - Susan M Watanabe
- the Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794
| | - Carol A Carter
- the Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794
| | - Jamil S Saad
- From the Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
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20
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He W, Mazzuca P, Yuan W, Varney K, Bugatti A, Cagnotto A, Giagulli C, Rusnati M, Marsico S, Diomede L, Salmona M, Caruso A, Lu W, Caccuri F. Identification of amino acid residues critical for the B cell growth-promoting activity of HIV-1 matrix protein p17 variants. Biochim Biophys Acta Gen Subj 2018; 1863:13-24. [PMID: 30248376 DOI: 10.1016/j.bbagen.2018.09.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 09/18/2018] [Accepted: 09/19/2018] [Indexed: 10/28/2022]
Abstract
BACKGROUND HIV-1 matrix protein p17 variants (vp17s) detected in HIV-1-infected patients with non-Hodgkin's lymphoma (HIV-NHL) display, differently from the wild-type protein (refp17), B cell growth-promoting activity. Biophysical analysis revealed that vp17s are destabilized as compared to refp17, motivating us to explore structure-function relationships. METHODS We used: biophysical techniques (circular dichroism (CD), nuclear magnetic resonance (NMR) and thermal/GuHCL denaturation) to study protein conformation and stability; Surface plasmon resonance (SPR) to study interactions; Western blot to investigate signaling pathways; and Colony Formation and Soft Agar assays to study B cell proliferation and clonogenicity. RESULTS By forcing the formation of a disulfide bridge between Cys residues at positions 57 and 87 we obtained a destabilized p17 capable of promoting B cell proliferation. This finding prompted us to dissect refp17 to identify the functional epitope. A synthetic peptide (F1) spanning from amino acid (aa) 2 to 21 was found to activate Akt and promote B cell proliferation and clonogenicity. Three positively charged aa (Arg15, Lys18 and Arg20) proved critical for sustaining the proliferative activity of both F1 and HIV-NHL-derived vp17s. Lack of any interaction of F1 with the known refp17 receptors suggests an alternate one involved in cell proliferation. CONCLUSIONS The molecular reasons for the proliferative activity of vp17s, compared to refp17, relies on the exposure of a functional epitope capable of activating Akt. GENERAL SIGNIFICANCE Our findings pave the way for identifying the receptor(s) responsible for B cell proliferation and offer new opportunities to identify novel treatment strategies in combating HIV-related NHL.
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Affiliation(s)
- Wangxiao He
- Center for Translational Medicine, Xi'an Jiaotong University School of Life Science and Technology, Xi'an, China.
| | - Pietro Mazzuca
- Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy.
| | - Weirong Yuan
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, USA.
| | - Kristen Varney
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, USA.
| | - Antonella Bugatti
- Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy.
| | - Alfredo Cagnotto
- IRCCS Istituto Ricerche Farmacologiche "Mario Negri", Milan, Italy.
| | - Cinzia Giagulli
- Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy.
| | - Marco Rusnati
- Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy.
| | - Stefania Marsico
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Italy.
| | - Luisa Diomede
- IRCCS Istituto Ricerche Farmacologiche "Mario Negri", Milan, Italy.
| | - Mario Salmona
- IRCCS Istituto Ricerche Farmacologiche "Mario Negri", Milan, Italy.
| | - Arnaldo Caruso
- Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy.
| | - Wuyuan Lu
- Center for Translational Medicine, Xi'an Jiaotong University School of Life Science and Technology, Xi'an, China; Institute of Human Virology, University of Maryland School of Medicine, Baltimore, USA; Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, USA.
| | - Francesca Caccuri
- Department of Molecular and Translational Medicine, University of Brescia Medical School, Brescia, Italy.
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21
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HIV-1 Matrix Protein Interactions with tRNA: Implications for Membrane Targeting. J Mol Biol 2018; 430:2113-2127. [PMID: 29752967 DOI: 10.1016/j.jmb.2018.04.042] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 04/30/2018] [Accepted: 04/30/2018] [Indexed: 12/31/2022]
Abstract
The N-terminally myristoylated matrix (MA) domain of the HIV-1 Gag polyprotein promotes virus assembly by targeting Gag to the inner leaflet of the plasma membrane. Recent studies indicate that, prior to membrane binding, MA associates with cytoplasmic tRNAs (including tRNALys3), and in vitro studies of tRNA-dependent MA interactions with model membranes have led to proposals that competitive tRNA interactions contribute to membrane discrimination. We have characterized interactions between native, mutant, and unmyristylated (myr-) MA proteins and recombinant tRNALys3 by NMR spectroscopy and isothermal titration calorimetry. NMR experiments confirm that tRNALys3 interacts with a patch of basic residues that are also important for binding to the plasma membrane marker, phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2]. Unexpectedly, the affinity of MA for tRNALys3 (Kd = 0.63 ± 0.03 μM) is approximately 1 order of magnitude greater than its affinity for PI(4,5)P2-enriched liposomes (Kd(apparent) = 10.2 ± 2.1 μM), and NMR studies indicate that tRNALys3 binding blocks MA association with liposomes, including those enriched with PI(4,5)P2, phosphatidylserine, and cholesterol. However, the affinity of MA for tRNALys3 is diminished by mutations or sample conditions that promote myristate exposure. Since Gag-Gag interactions are known to promote myristate exposure, our findings support virus assembly models in which membrane targeting and genome binding are mechanistically coupled.
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22
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Konagaya Y, Miyakawa R, Sato M, Matsugami A, Watanabe S, Hayashi F, Kigawa T, Nishimura C. Effect of Glu12-His89 Interaction on Dynamic Structures in HIV-1 p17 Matrix Protein Elucidated by NMR. PLoS One 2016; 11:e0167176. [PMID: 27907055 PMCID: PMC5132258 DOI: 10.1371/journal.pone.0167176] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 11/09/2016] [Indexed: 11/18/2022] Open
Abstract
To test the existence of the salt bridge and stability of the HIV-1 p17 matrix protein, an E12A (mutated at helix 1) was established to abolish possible electrostatic interactions. The chemical shift perturbation from the comparison between wild type and E12A suggested the existence of an electrostatic interaction in wild type between E12 and H89 (located in helix 4). Unexpectedly, the studies using urea denaturation indicated that the E12A substitution slightly stabilized the protein. The dynamic structure of E12A was examined under physiological conditions by both amide proton exchange and relaxation studies. The quick exchange method of amide protons revealed that the residues with faster exchange were located at the mutated region, around A12, compared to those of the wild-type protein. In addition, some residues at the region of helix 4, including H89, exhibited faster exchange in the mutant. In contrast, the average values of the kinetic rate constants for amide proton exchange for residues located in all loop regions were slightly lower in E12A than in wild type. Furthermore, the analyses of the order parameter revealed that less flexible structures existed at each loop region in E12A. Interestingly, the structures of the regions including the alpha1-2 loop and helix 5 of E12A exhibited more significant conformational exchanges with the NMR time-scale than those of wild type. Under lower pH conditions, for further destabilization, the helix 1 and alpha2-3 loop in E12A became more fluctuating than at physiological pH. Because the E12A mutant lacks the activities for trimer formation on the basis of the analytical ultra-centrifuge studies on the sedimentation distribution of p17 (Fledderman et al. Biochemistry 49, 9551–9562, 2010), it is possible that the changes in the dynamic structures induced by the absence of the E12-H89 interaction in the p17 matrix protein contributes to a loss of virus assembly.
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Affiliation(s)
- Yuta Konagaya
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano, Tokyo, Japan
| | - Rina Miyakawa
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano, Tokyo, Japan
| | - Masumi Sato
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano, Tokyo, Japan
| | - Akimasa Matsugami
- Division of Structural and Synthetic Biology, RIKEN Center for Life Science Technologies, Yokohama, Kanagawa, Japan
| | - Satoru Watanabe
- Laboratory for Biomolecular Structure and Dynamics, RIKEN Quantitative Biology Center, Yokohama, Kanagawa, Japan
| | - Fumiaki Hayashi
- Division of Structural and Synthetic Biology, RIKEN Center for Life Science Technologies, Yokohama, Kanagawa, Japan
| | - Takanori Kigawa
- Laboratory for Biomolecular Structure and Dynamics, RIKEN Quantitative Biology Center, Yokohama, Kanagawa, Japan
| | - Chiaki Nishimura
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano, Tokyo, Japan
- * E-mail:
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23
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Agamasu C, Ghanam RH, Xu F, Sun Y, Chen Y, Saad JS. The Interplay between Calmodulin and Membrane Interactions with the Pleckstrin Homology Domain of Akt. J Biol Chem 2016; 292:251-263. [PMID: 27872186 DOI: 10.1074/jbc.m116.752816] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 11/19/2016] [Indexed: 11/06/2022] Open
Abstract
The Akt protein, a serine/threonine kinase, plays important roles in cell survival, apoptosis, and oncogenes. Akt is translocated to the plasma membrane for activation. Akt-membrane binding is mediated by direct interactions between its pleckstrin homology domain (PHD) and phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3). It has been shown that Akt activation in breast cancer cells is modulated by calmodulin (CaM). However, the molecular mechanism of the interplay between CaM and membrane binding is not established. Here, we employed nuclear magnetic resonance (NMR) and biochemical and biophysical techniques to characterize how PI(3,4,5)P3, CaM, and membrane mimetics (nanodisc) bind to Akt(PHD). We show that PI(3,4,5)P3 binding to Akt(PHD) displaces the C-terminal lobe of CaM but not the weakly binding N-terminal lobe. However, binding of a PI(3,4,5)P3-embedded membrane nanodisc to Akt(PHD) with a 103-fold tighter affinity than PI(3,4,5)P3 is able to completely displace CaM. We also show that Akt(PHD) binds to both layers of the nanodisc, indicating proper incorporation of PI(3,4,5)P3 on the nanodisc surface. No detectable binding has been observed between Akt(PHD) and PI(3,4,5)P3-free nanodiscs, demonstrating that PI(3,4,5)P3 is required for membrane binding, CaM displacement, and Akt activation. Using pancreatic cancer cells, we demonstrate that inhibition of Akt-CaM binding attenuated Akt activation. Our findings support a model by which CaM binds to Akt to facilitate its translocation to the membrane. Elucidation of the molecular details of the interplay between membrane and CaM binding to Akt may help in the development of potential targets to control the pathophysiological processes of cell survival.
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Affiliation(s)
| | | | - Fei Xu
- Pathology, University of Alabama at Birmingham and
| | - Yong Sun
- Pathology, University of Alabama at Birmingham and.,the Research Department, Birmingham Veterans Affairs Medical Center, Birmingham, Alabama 35294
| | - Yabing Chen
- Pathology, University of Alabama at Birmingham and.,the Research Department, Birmingham Veterans Affairs Medical Center, Birmingham, Alabama 35294
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24
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Spearman P. HIV-1 Gag as an Antiviral Target: Development of Assembly and Maturation Inhibitors. Curr Top Med Chem 2016; 16:1154-66. [PMID: 26329615 DOI: 10.2174/1568026615666150902102143] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 06/18/2015] [Accepted: 06/21/2015] [Indexed: 01/10/2023]
Abstract
HIV-1 Gag is the master orchestrator of particle assembly. The central role of Gag at multiple stages of the HIV lifecycle has led to efforts to develop drugs that directly target Gag and prevent the formation and release of infectious particles. Until recently, however, only the catalytic site protease inhibitors have been available to inhibit late stages of HIV replication. This review summarizes the current state of development of antivirals that target Gag or disrupt late events in the retrovirus lifecycle such as maturation of the viral capsid. Maturation inhibitors represent an exciting new series of antiviral compounds, including those that specifically target CA-SP1 cleavage and the allosteric integrase inhibitors that inhibit maturation by a completely different mechanism. Numerous small molecules and peptides targeting CA have been studied in attempts to disrupt steps in assembly. Efforts to target CA have recently gained considerable momentum from the development of small molecules that bind CA and alter capsid stability at the post-entry stage of the lifecycle. Efforts to develop antivirals that inhibit incorporation of genomic RNA or to inhibit late budding events remain in preliminary stages of development. Overall, the development of novel antivirals targeting Gag and the late stages in HIV replication appears much closer to success than ever, with the new maturation inhibitors leading the way.
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Affiliation(s)
- Paul Spearman
- Department of Pediatrics; Pediatric Infectious Diseases, Emory University, 2015 Uppergate Drive, Atlanta, GA 30322.
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25
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Effects of Membrane Charge and Order on Membrane Binding of the Retroviral Structural Protein Gag. J Virol 2016; 90:9518-32. [PMID: 27512076 DOI: 10.1128/jvi.01102-16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/05/2016] [Indexed: 12/28/2022] Open
Abstract
UNLABELLED The retroviral structural protein Gag binds to the inner leaflet of the plasma membrane (PM), and many cellular proteins do so as well. We used Rous sarcoma virus (RSV) Gag together with membrane sensors to study the principles governing peripheral protein membrane binding, including electrostatics, specific recognition of phospholipid headgroups, sensitivity to phospholipid acyl chain compositions, preference for membrane order, and protein multimerization. We used an in vitro liposome-pelleting assay to test protein membrane binding properties of Gag, the well-characterized MARCKS peptide, a series of fluorescent electrostatic sensor proteins (mNG-KRn), and the specific phosphatidylserine (PS) binding protein Evectin2. RSV Gag and mNG-KRn bound well to membranes with saturated and unsaturated acyl chains, whereas the MARCKS peptide and Evectin2 preferentially bound to membranes with unsaturated acyl chains. To further discriminate whether the primary driving force for Gag membrane binding is electrostatic interactions or preference for membrane order, we measured protein binding to giant unilamellar vesicles (GUVs) containing the same PS concentration in both disordered (Ld) and ordered (Lo) phases. RSV Gag and mNG-KRn membrane association followed membrane charge, independent of membrane order. Consistent with pelleting data, the MARCKS peptide showed preference for the Ld domain. Surprisingly, the PS sensor Evectin2 bound to the PS-rich Ld domain with 10-fold greater affinity than to the PS-rich Lo domain. In summary, we found that RSV Gag shows no preference for membrane order, while proteins with reported membrane-penetrating domains show preference for disordered membranes. IMPORTANCE Retroviral particles assemble on the PM and bud from infected cells. Our understanding of how Gag interacts with the PM and how different membrane properties contribute to overall Gag assembly is incomplete. This study examined how membrane charge and membrane order influence Gag membrane association. Consistent with previous work on RSV Gag, we report here that electrostatic interactions provide the primary driving force for RSV Gag membrane association. Using phase-separated GUVs with known lipid composition of the Ld and Lo phases, we demonstrate for the first time that RSV Gag is sensitive to membrane charge but not membrane order. In contrast, the cellular protein domain MARCKS and the PS sensor Evectin2 show preference for disordered membranes. We also demonstrate how to define GUV phase composition, which could serve as a tool in future studies of protein membrane interactions.
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26
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Junková P, Prchal J, Spiwok V, Pleskot R, Kadlec J, Krásný L, Hynek R, Hrabal R, Ruml T. Molecular aspects of the interaction between Mason-Pfizer monkey virus matrix protein and artificial phospholipid membrane. Proteins 2016; 84:1717-1727. [PMID: 27578150 DOI: 10.1002/prot.25156] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 08/04/2016] [Accepted: 08/25/2016] [Indexed: 11/09/2022]
Abstract
The Mason-Pfizer monkey virus is a type D retrovirus, which assembles its immature particles in the cytoplasm prior to their transport to the host cell membrane. The association with the membrane is mediated by the N-terminally myristoylated matrix protein. To reveal the role of particular residues which are involved in the capsid-membrane interaction, covalent labelling of arginine, lysine and tyrosine residues of the Mason-Pfizer monkey virus matrix protein bound to artificial liposomes containing 95% of phosphatidylcholine and 5% phosphatidylinositol-(4,5)-bisphosphate (PI(4,5)P2 ) was performed. The experimental results were interpreted by multiscale molecular dynamics simulations. The application of these two complementary approaches helped us to reveal that matrix protein specifically recognizes the PI(4,5)P2 molecule by the residues K20, K25, K27, K74, and Y28, while the residues K92 and K93 stabilizes the matrix protein orientation on the membrane by the interaction with another PI(4,5)P2 molecule. Residues K33, K39, K54, Y66, Y67, and K87 appear to be involved in the matrix protein oligomerization. All arginine residues remained accessible during the interaction with liposomes which indicates that they neither contribute to the interaction with membrane nor are involved in protein oligomerization. Proteins 2016; 84:1717-1727. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- P Junková
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Czech Republic.
| | - J Prchal
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Czech Republic
| | - V Spiwok
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Czech Republic
| | - R Pleskot
- Laboratory of Cell Biology, Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic.,Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - J Kadlec
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - L Krásný
- Laboratory of molecular structure characterisation, Institute of Microbiology of the ASCR, Academy of Sciences of the Czech Republic, Prague, Czech Republic.,Department of Cancer Biology, Institute of Cancer Research, London, United Kingdom
| | - R Hynek
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Czech Republic
| | - R Hrabal
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Czech Republic
| | - T Ruml
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Czech Republic
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27
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Kijewski SDG, Akiyama H, Feizpour A, Miller CM, Ramirez NGP, Reinhard BM, Gummuluru S. Access of HIV-2 to CD169-dependent dendritic cell-mediated trans infection pathway is attenuated. Virology 2016; 497:328-336. [PMID: 27521724 DOI: 10.1016/j.virol.2016.07.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 07/27/2016] [Accepted: 07/28/2016] [Indexed: 10/21/2022]
Abstract
The mechanisms behind the low viral loads and lower mortality rates of HIV-2(+) individuals remain unknown. We hypothesized that reduced interaction of HIV-2 with CD169, the primary HIV-1 attachment factor on monocyte-derived dendritic cells (DCs) that targets captured virus particles to the trans infection pathway, contributes to its diminished pathogenic phenotype in vivo. We observed a significant decrease in capture of HIV-2 Gag-eGFP virus-like particles (VLPs) and infectious GFP-containing HIV-2 particles compared to corresponding HIV-1 particles by CD169(+) mature DCs. Interestingly, there was decreased co-localization of HIV-2 with HIV-1 Gag at plasma membrane microdomains in virus producer cells which correlated with reduced incorporation of GM3, the CD169 ligand, in HIV-2 virions, and reduction in mature DC-mediated HIV-2 trans infection compared to HIV-1. We conclude that limited interaction of HIV-2 with CD169 diminishes virus access to the mature DC-mediated trans infection pathway and might result in attenuated HIV-2 dissemination in vivo.
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Affiliation(s)
- Suzanne D G Kijewski
- Department of Microbiology, Boston University School of Medicine, Boston, MA 02118, USA.
| | - Hisashi Akiyama
- Department of Microbiology, Boston University School of Medicine, Boston, MA 02118, USA.
| | - Amin Feizpour
- Department of Chemistry and The Photonics Center, Boston University, Boston, MA 02215, USA.
| | - Caitlin M Miller
- Department of Pathology, Boston University School of Medicine, Boston, MA 02118, USA.
| | | | - Björn M Reinhard
- Department of Chemistry and The Photonics Center, Boston University, Boston, MA 02215, USA.
| | - Suryaram Gummuluru
- Department of Microbiology, Boston University School of Medicine, Boston, MA 02118, USA.
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28
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Human Immunodeficiency Virus Type 2 (HIV-2) Gag Is Trafficked in an AP-3 and AP-5 Dependent Manner. PLoS One 2016; 11:e0158941. [PMID: 27392064 PMCID: PMC4938559 DOI: 10.1371/journal.pone.0158941] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 06/24/2016] [Indexed: 02/03/2023] Open
Abstract
Although human immunodeficiency virus (HIV) types 1 and 2 are closely related lentiviruses with similar replication cycles, HIV-2 infection is associated with slower progression to AIDS, a higher proportion of long term non-progressors, and lower rates of transmission than HIV-1, likely as a consequence of a lower viral load during HIV-2 infection. A mechanistic explanation for the differential viral load remains unclear but knowledge of differences in particle production between HIV-1 and HIV-2 may help to shed light on this issue. In contrast to HIV-1, little is known about the assembly of HIV-2 particles, and the trafficking of HIV-2 Gag, the structural component of the virus, within cells. We have established that HIV-2 Gag accumulates in intracellular CD63 positive compartments, from which it may be delivered or recycled to the cell surface, or degraded. HIV-2 particle release was dependent on the adaptor protein complex AP-3 and the newly identified AP-5 complex, but much less so on AP-1. In contrast, HIV-1 particle release required AP-1 and AP-3, but not AP-5. AP-2, an essential component of clathrin-mediated endocytosis, which was previously shown to be inhibitory to HIV-1 particle release, had no effect on HIV-2. The differential requirement for adaptor protein complexes confirmed that HIV-1 and HIV-2 Gag have distinct cellular trafficking pathways, and that HIV-2 particles may be more susceptible to degradation prior to release.
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29
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Pachulska-Wieczorek K, Błaszczyk L, Biesiada M, Adamiak RW, Purzycka KJ. The matrix domain contributes to the nucleic acid chaperone activity of HIV-2 Gag. Retrovirology 2016; 13:18. [PMID: 26987314 PMCID: PMC4794849 DOI: 10.1186/s12977-016-0245-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 02/17/2016] [Indexed: 01/17/2023] Open
Abstract
Background The Gag polyprotein is a multifunctional regulator of retroviral replication and major structural component of immature virions. The nucleic acid chaperone (NAC) activity is considered necessary to retroviral Gag functions, but so far, NAC activity has only been confirmed for HIV-1 and RSV Gag polyproteins. The nucleocapsid (NC) domain of Gag is proposed to be crucial for interactions with nucleic acids and NAC activity. The major function of matrix (MA) domain is targeting and binding of Gag to the plasma membrane but MA can also interact with RNA and influence NAC activity of Gag. Here, we characterize RNA binding properties and NAC activity of HIV-2 MA and Gag, lacking p6 domain (GagΔp6) and discuss potential contribution of NC and MA domains to HIV-2 GagΔp6 functions and interactions with RNA. Results We found that HIV-2 GagΔp6 is a robust nucleic acid chaperone. HIV-2 MA protein promotes nucleic acids aggregation and tRNALys3 annealing in vitro. The NAC activity of HIV-2 NC is affected by salt which is in contrast to HIV-2 GagΔp6 and MA. At a physiological NaCl concentration the tRNALys3 annealing activity of HIV-2 GagΔp6 or MA is higher than HIV-2 NC. The HIV-2 NC and GagΔp6 show strong binding to the packaging signal (Ψ) of HIV-2 RNA and preference for the purine-rich sequences, while MA protein binds mainly to G residues without favouring Ψ RNA. Moreover, HIV-2 GagΔp6 and NC promote HIV-2 RNA dimerization while our data do not support MA domain participation in this process in vitro. Conclusions We present that contrary to HIV-1 MA, HIV-2 MA displays NAC activity and we propose that MA domain may enhance the activity of HIV-2 GagΔp6. The role of the MA domain in the NAC activity of Gag may differ significantly between HIV-1 and HIV-2. The HIV-2 NC and MA interactions with RNA are not equivalent. Even though both NC and MA can facilitate tRNALys3 annealing, MA does not participate in RNA dimerization in vitro. Our data on HIV-2 indicate that the role of the MA domain in the NAC activity of Gag differs not only between, but also within, retroviral genera. Electronic supplementary material The online version of this article (doi:10.1186/s12977-016-0245-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Leszek Błaszczyk
- Institute of Computing Science, Poznan University of Technology, Piotrowo 2, 60-965, Poznan, Poland
| | - Marcin Biesiada
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland.,Institute of Computing Science, Poznan University of Technology, Piotrowo 2, 60-965, Poznan, Poland
| | - Ryszard W Adamiak
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland.,Institute of Computing Science, Poznan University of Technology, Piotrowo 2, 60-965, Poznan, Poland
| | - Katarzyna J Purzycka
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland.
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30
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Mercredi PY, Bucca N, Loeliger B, Gaines CR, Mehta M, Bhargava P, Tedbury PR, Charlier L, Floquet N, Muriaux D, Favard C, Sanders CR, Freed EO, Marchant J, Summers MF. Structural and Molecular Determinants of Membrane Binding by the HIV-1 Matrix Protein. J Mol Biol 2016; 428:1637-55. [PMID: 26992353 DOI: 10.1016/j.jmb.2016.03.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 03/09/2016] [Accepted: 03/10/2016] [Indexed: 10/22/2022]
Abstract
Assembly of HIV-1 particles is initiated by the trafficking of viral Gag polyproteins from the cytoplasm to the plasma membrane, where they co-localize and bud to form immature particles. Membrane targeting is mediated by the N-terminally myristoylated matrix (MA) domain of Gag and is dependent on the plasma membrane marker phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2]. Recent studies revealed that PI(4,5)P2 molecules containing truncated acyl chains [tr-PI(4,5)P2] are capable of binding MA in an "extended lipid" conformation and promoting myristoyl exposure. Here we report that tr-PI(4,5)P2 molecules also readily bind to non-membrane proteins, including HIV-1 capsid, which prompted us to re-examine MA-PI(4,5)P2 interactions using native lipids and membrane mimetic liposomes and bicelles. Liposome binding trends observed using a recently developed NMR approach paralleled results of flotation assays, although the affinities measured under the equilibrium conditions of NMR experiments were significantly higher. Native PI(4,5)P2 enhanced MA binding to liposomes designed to mimic non-raft-like regions of the membrane, suggesting the possibility that binding of the protein to disordered domains may precede Gag association with, or nucleation of, rafts. Studies with bicelles revealed a subset of surface and myr-associated MA residues that are sensitive to native PI(4,5)P2, but cleft residues that interact with the 2'-acyl chains of tr-PI(4,5)P2 molecules in aqueous solution were insensitive to native PI(4,5)P2 in bicelles. Our findings call to question extended-lipid MA:membrane binding models, and instead support a model put forward from coarse-grained simulations indicating that binding is mediated predominantly by dynamic, electrostatic interactions between conserved basic residues of MA and multiple PI(4,5)P2 and phosphatidylserine molecules.
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Affiliation(s)
- Peter Y Mercredi
- Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Nadine Bucca
- Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Burk Loeliger
- Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Christy R Gaines
- Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Mansi Mehta
- Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Pallavi Bhargava
- Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Philip R Tedbury
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, National Cancer Institute at Fredrick, Fredrick, MD 21702-1201, USA
| | - Landry Charlier
- Institut des Biomolécules Max Mousseron, CNRS UMR5247, Université Montpellier, Faculté de Pharmacie, Montpellier Cedex 05, France
| | - Nicolas Floquet
- Institut des Biomolécules Max Mousseron, CNRS UMR5247, Université Montpellier, Faculté de Pharmacie, Montpellier Cedex 05, France
| | - Delphine Muriaux
- Centre d'études d'agents Pathogénes et Biotechnologies pour la Santé CNRS-UMR 5236, Université Montpellier, Montpellier Cedex 5, France
| | - Cyril Favard
- Centre d'études d'agents Pathogénes et Biotechnologies pour la Santé CNRS-UMR 5236, Université Montpellier, Montpellier Cedex 5, France
| | - Charles R Sanders
- Department of Biochemistry, Center for Structural Biology, and Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, TN 37240-7917, USA
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, National Cancer Institute at Fredrick, Fredrick, MD 21702-1201, USA.
| | - Jan Marchant
- Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, University of Maryland, Baltimore County, Baltimore, MD 21250, USA.
| | - Michael F Summers
- Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, University of Maryland, Baltimore County, Baltimore, MD 21250, USA.
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31
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The Ebola Virus matrix protein, VP40, requires phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) for extensive oligomerization at the plasma membrane and viral egress. Sci Rep 2016; 6:19125. [PMID: 26753796 PMCID: PMC4709572 DOI: 10.1038/srep19125] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 12/07/2015] [Indexed: 12/25/2022] Open
Abstract
VP40 is one of eight proteins encoded by the Ebola Virus (EBOV) and serves as the primary matrix protein, forming virus like particles (VLPs) from mammalian cells without the need for other EBOV proteins. While VP40 is required for viral assembly and budding from host cells during infection, the mechanisms that target VP40 to the plasma membrane are not well understood. Phosphatidylserine is required for VP40 plasma membrane binding, VP40 hexamer formation, and VLP egress, However, PS also becomes exposed on the outer membrane leaflet at sites of VP40 budding, raising the question of how VP40 maintains an interaction with the plasma membrane inner leaflet when PS is flipped to the opposite side. To address this question, cellular and in vitro assays were employed to determine if phosphoinositides are important for efficient VP40 localization to the plasma membrane. Cellular studies demonstrated that PI(4,5)P2 was an important component of VP40 assembly at the plasma membrane and subsequent virus like particle formation. Additionally, PI(4,5)P2 was required for formation of extensive oligomers of VP40, suggesting PS and PI(4,5)P2 have different roles in VP40 assembly where PS regulates formation of hexamers from VP40 dimers and PI(4,5)P2 stabilizes and/or induces extensive VP40 oligomerization at the plasma membrane.
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Doležal M, Zábranský A, Dostál J, Vaněk O, Brynda J, Lepšík M, Hadravová R, Pichová I. Myristoylation drives dimerization of matrix protein from mouse mammary tumor virus. Retrovirology 2016; 13:2. [PMID: 26728401 PMCID: PMC4700671 DOI: 10.1186/s12977-015-0235-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 12/22/2015] [Indexed: 11/25/2022] Open
Abstract
Background Myristoylation of the matrix (MA) domain mediates the transport and binding of Gag polyproteins to the plasma membrane (PM) and is required for the assembly of most retroviruses. In betaretroviruses, which assemble immature particles in the cytoplasm, myristoylation is dispensable for assembly but is crucial for particle transport to the PM. Oligomerization of HIV-1 MA stimulates the transition of the myristoyl group from a sequestered to an exposed conformation, which is more accessible for membrane binding. However, for other retroviruses, the effect of MA oligomerization on myristoyl group exposure has not been thoroughly investigated. Results Here, we demonstrate that MA from the betaretrovirus mouse mammary tumor virus (MMTV) forms dimers in solution and that this process is stimulated by its myristoylation. The crystal structure of N-myristoylated MMTV MA, determined at 1.57 Å resolution, revealed that the myristoyl groups are buried in a hydrophobic pocket at the dimer interface and contribute to dimer formation. Interestingly, the myristoyl groups in the dimer are mutually swapped to achieve energetically stable binding, as documented by molecular dynamics modeling. Mutations within the myristoyl binding site resulted in reduced MA dimerization and extracellular particle release. Conclusions Based on our experimental, structural, and computational data, we propose a model for dimerization of MMTV MA in which myristoyl groups stimulate the interaction between MA molecules. Moreover, dimer-forming MA molecules adopt a sequestered conformation with their myristoyl groups entirely buried within the interaction interface. Although this differs from the current model proposed for lentiviruses, in which oligomerization of MA triggers exposure of myristoyl group, it appears convenient for intracellular assembly, which involves no apparent membrane interaction and allows the myristoyl group to be sequestered during oligomerization. Electronic supplementary material The online version of this article (doi:10.1186/s12977-015-0235-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Michal Doležal
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10, Prague, Czech Republic.
| | - Aleš Zábranský
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10, Prague, Czech Republic.
| | - Jiří Dostál
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10, Prague, Czech Republic.
| | - Ondřej Vaněk
- Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 40, Prague, Czech Republic.
| | - Jiří Brynda
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10, Prague, Czech Republic.
| | - Martin Lepšík
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10, Prague, Czech Republic.
| | - Romana Hadravová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10, Prague, Czech Republic.
| | - Iva Pichová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10, Prague, Czech Republic.
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Hendrix J, Baumgärtel V, Schrimpf W, Ivanchenko S, Digman MA, Gratton E, Kräusslich HG, Müller B, Lamb DC. Live-cell observation of cytosolic HIV-1 assembly onset reveals RNA-interacting Gag oligomers. J Cell Biol 2015; 210:629-46. [PMID: 26283800 PMCID: PMC4539982 DOI: 10.1083/jcb.201504006] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Analysis of the cytosolic HIV-1 Gag fraction in live cells via advanced fluctuation imaging methods reveals potential nucleation steps before membrane-assisted Gag assembly. Assembly of the Gag polyprotein into new viral particles in infected cells is a crucial step in the retroviral replication cycle. Currently, little is known about the onset of assembly in the cytosol. In this paper, we analyzed the cytosolic HIV-1 Gag fraction in real time in live cells using advanced fluctuation imaging methods and thereby provide detailed insights into the complex relationship between cytosolic Gag mobility, stoichiometry, and interactions. We show that Gag diffuses as a monomer on the subsecond timescale with severely reduced mobility. Reduction of mobility is associated with basic residues in its nucleocapsid (NC) domain, whereas capsid (CA) and matrix (MA) domains do not contribute significantly. Strikingly, another diffusive Gag species was observed on the seconds timescale that oligomerized in a concentration-dependent manner. Both NC- and CA-mediated interactions strongly assist this process. Our results reveal potential nucleation steps of cytosolic Gag fractions before membrane-assisted Gag assembly.
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Affiliation(s)
- Jelle Hendrix
- Physical Chemistry, Department of Chemistry, Ludwig Maximilian University of Munich, D-81377 Munich, Germany NanoSystems Initiative Munich (NIM), Ludwig Maximilian University of Munich, D-81377 Munich, Germany Munich Center for Integrated Protein Science (CiPSM), Ludwig Maximilian University of Munich, D-81377 Munich, Germany Center for Nanoscience (CeNS), Ludwig Maximilian University of Munich, D-81377 Munich, Germany
| | - Viola Baumgärtel
- Physical Chemistry, Department of Chemistry, Ludwig Maximilian University of Munich, D-81377 Munich, Germany NanoSystems Initiative Munich (NIM), Ludwig Maximilian University of Munich, D-81377 Munich, Germany Munich Center for Integrated Protein Science (CiPSM), Ludwig Maximilian University of Munich, D-81377 Munich, Germany Center for Nanoscience (CeNS), Ludwig Maximilian University of Munich, D-81377 Munich, Germany
| | - Waldemar Schrimpf
- Physical Chemistry, Department of Chemistry, Ludwig Maximilian University of Munich, D-81377 Munich, Germany NanoSystems Initiative Munich (NIM), Ludwig Maximilian University of Munich, D-81377 Munich, Germany Munich Center for Integrated Protein Science (CiPSM), Ludwig Maximilian University of Munich, D-81377 Munich, Germany Center for Nanoscience (CeNS), Ludwig Maximilian University of Munich, D-81377 Munich, Germany
| | - Sergey Ivanchenko
- Physical Chemistry, Department of Chemistry, Ludwig Maximilian University of Munich, D-81377 Munich, Germany NanoSystems Initiative Munich (NIM), Ludwig Maximilian University of Munich, D-81377 Munich, Germany Munich Center for Integrated Protein Science (CiPSM), Ludwig Maximilian University of Munich, D-81377 Munich, Germany Center for Nanoscience (CeNS), Ludwig Maximilian University of Munich, D-81377 Munich, Germany
| | - Michelle A Digman
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697 Development Biology Center Optical Biology Core Facility, University of California, Irvine, Irvine, CA 92697
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697 Development Biology Center Optical Biology Core Facility, University of California, Irvine, Irvine, CA 92697
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, D-69120 Heidelberg, Germany
| | - Barbara Müller
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, D-69120 Heidelberg, Germany
| | - Don C Lamb
- Physical Chemistry, Department of Chemistry, Ludwig Maximilian University of Munich, D-81377 Munich, Germany NanoSystems Initiative Munich (NIM), Ludwig Maximilian University of Munich, D-81377 Munich, Germany Munich Center for Integrated Protein Science (CiPSM), Ludwig Maximilian University of Munich, D-81377 Munich, Germany Center for Nanoscience (CeNS), Ludwig Maximilian University of Munich, D-81377 Munich, Germany
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Involvement of the Rac1-IRSp53-Wave2-Arp2/3 Signaling Pathway in HIV-1 Gag Particle Release in CD4 T Cells. J Virol 2015; 89:8162-81. [PMID: 26018170 DOI: 10.1128/jvi.00469-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Accepted: 05/14/2015] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED During HIV-1 assembly, the Gag viral proteins are targeted and assemble at the inner leaflet of the cell plasma membrane. This process could modulate the cortical actin cytoskeleton, located underneath the plasma membrane, since actin dynamics are able to promote localized membrane reorganization. In addition, activated small Rho GTPases are known for regulating actin dynamics and membrane remodeling. Therefore, the modulation of such Rho GTPase activity and of F-actin by the Gag protein during virus particle formation was considered. Here, we studied the implication of the main Rac1, Cdc42, and RhoA small GTPases, and some of their effectors, in this process. The effect of small interfering RNA (siRNA)-mediated Rho GTPases and silencing of their effectors on Gag localization, Gag membrane attachment, and virus-like particle production was analyzed by immunofluorescence coupled to confocal microscopy, membrane flotation assays, and immunoblot assays, respectively. In parallel, the effect of Gag expression on the Rac1 activation level was monitored by G-LISA, and the intracellular F-actin content in T cells was monitored by flow cytometry and fluorescence microscopy. Our results revealed the involvement of activated Rac1 and of the IRSp53-Wave2-Arp2/3 signaling pathway in HIV-1 Gag membrane localization and particle release in T cells as well as a role for actin branching and polymerization, and this was solely dependent on the Gag viral protein. In conclusion, our results highlight a new role for the Rac1-IRSp53-Wave2-Arp2/3 signaling pathway in the late steps of HIV-1 replication in CD4 T lymphocytes. IMPORTANCE During HIV-1 assembly, the Gag proteins are targeted and assembled at the inner leaflet of the host cell plasma membrane. Gag interacts with specific membrane phospholipids that can also modulate the regulation of cortical actin cytoskeleton dynamics. Actin dynamics can promote localized membrane reorganization and thus can be involved in facilitating Gag assembly and particle formation. Activated small Rho GTPases and effectors are regulators of actin dynamics and membrane remodeling. We thus studied the effects of the Rac1, Cdc42, and RhoA GTPases and their specific effectors on HIV-1 Gag membrane localization and viral particle release in T cells. Our results show that activated Rac1 and the IRSp53-Wave2-Arp2/3 signaling pathway are involved in Gag plasma membrane localization and viral particle production. This work uncovers a role for cortical actin through the activation of Rac1 and the IRSp53/Wave2 signaling pathway in HIV-1 particle formation in CD4 T lymphocytes.
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Brown LA, Cox C, Baptiste J, Summers H, Button R, Bahlow K, Spurrier V, Kyser J, Luttge BG, Kuo L, Freed EO, Summers MF. NMR structure of the myristylated feline immunodeficiency virus matrix protein. Viruses 2015; 7:2210-29. [PMID: 25941825 PMCID: PMC4452903 DOI: 10.3390/v7052210] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 03/30/2015] [Accepted: 04/21/2015] [Indexed: 11/25/2022] Open
Abstract
Membrane targeting by the Gag proteins of the human immunodeficiency viruses (HIV types-1 and -2) is mediated by Gag's N-terminally myristylated matrix (MA) domain and is dependent on cellular phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2]. To determine if other lentiviruses employ a similar membrane targeting mechanism, we initiated studies of the feline immunodeficiency virus (FIV), a widespread feline pathogen with potential utility for development of human therapeutics. Bacterial co-translational myristylation was facilitated by mutation of two amino acids near the amino-terminus of the protein (Q5A/G6S; myrMAQ5A/G6S). These substitutions did not affect virus assembly or release from transfected cells. NMR studies revealed that the myristyl group is buried within a hydrophobic pocket in a manner that is structurally similar to that observed for the myristylated HIV-1 protein. Comparisons with a recent crystal structure of the unmyristylated FIV protein [myr(-)MA] indicate that only small changes in helix orientation are required to accommodate the sequestered myr group. Depletion of PI(4,5)P2 from the plasma membrane of FIV-infected CRFK cells inhibited production of FIV particles, indicating that, like HIV, FIV hijacks the PI(4,5)P2 cellular signaling system to direct intracellular Gag trafficking during virus assembly.
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Affiliation(s)
- Lola A Brown
- Howard Hughes Medical Institute, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
| | - Cassiah Cox
- Howard Hughes Medical Institute, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
| | - Janae Baptiste
- Howard Hughes Medical Institute, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
| | - Holly Summers
- Howard Hughes Medical Institute, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
| | - Ryan Button
- Howard Hughes Medical Institute, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
| | - Kennedy Bahlow
- Howard Hughes Medical Institute, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
| | - Vaughn Spurrier
- Howard Hughes Medical Institute, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
| | - Jenna Kyser
- Howard Hughes Medical Institute, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
| | - Benjamin G Luttge
- Virus-Cell Interaction Section, HIV Drug Resistance Program, National Cancer Institute at Frederick, Frederick, MD 21702-1201, USA.
| | - Lillian Kuo
- Virus-Cell Interaction Section, HIV Drug Resistance Program, National Cancer Institute at Frederick, Frederick, MD 21702-1201, USA.
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Drug Resistance Program, National Cancer Institute at Frederick, Frederick, MD 21702-1201, USA.
| | - Michael F Summers
- Howard Hughes Medical Institute, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
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Vlach J, Saad JS. Structural and molecular determinants of HIV-1 Gag binding to the plasma membrane. Front Microbiol 2015; 6:232. [PMID: 25852680 PMCID: PMC4367181 DOI: 10.3389/fmicb.2015.00232] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 03/10/2015] [Indexed: 01/10/2023] Open
Abstract
Targeting of the Gag polyprotein to the plasma membrane (PM) for assembly is a critical event in the late phase of immunodeficiency virus type-1 (HIV-1) infection. Gag binding to the PM is mediated by interactions between the myristoylated matrix (MA) domain and PM lipids. Despite the extensive biochemical and in vitro studies of Gag and MA binding to membranes over the last two decades, the discovery of the role of phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2] in Gag binding to the PM has sparked a string of studies aimed at elucidating the molecular mechanism of retroviral Gag–PM binding. Electrostatic interactions between a highly conserved basic region of MA and acidic phospholipids have long been thought to be the main driving force for Gag–membrane interactions. However, recent studies suggest that the mechanism is rather complex since other factors such as the hydrophobicity of the membrane interior represented by the acyl chains and cholesterol also play important roles. Here we summarize the current understanding of HIV-1 Gag–membrane interactions at the molecular and structural levels and briefly discuss the underlying forces governing interactions of other retroviral MA proteins with the PM.
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Affiliation(s)
- Jiri Vlach
- Department of Microbiology, University of Alabama at Birmingham , Birmingham, AL, USA
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham , Birmingham, AL, USA
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Inlora J, Collins DR, Trubin ME, Chung JYJ, Ono A. Membrane binding and subcellular localization of retroviral Gag proteins are differentially regulated by MA interactions with phosphatidylinositol-(4,5)-bisphosphate and RNA. mBio 2014; 5:e02202. [PMID: 25491356 PMCID: PMC4324246 DOI: 10.1128/mbio.02202-14] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 11/07/2014] [Indexed: 01/29/2023] Open
Abstract
UNLABELLED The matrix (MA) domain of HIV-1 mediates proper Gag localization and membrane binding via interaction with a plasma-membrane (PM)-specific acidic phospholipid, phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P2]. HIV-1 MA also interacts with RNA, which prevents Gag from binding to membranes containing phosphatidylserine, a prevalent cellular acidic phospholipid. These results suggest that the MA-bound RNA promotes PM-specific localization of HIV-1 Gag by blocking nonspecific interactions with cellular membranes that do not contain PI(4,5)P2. To examine whether PI(4,5)P2 dependence and RNA-mediated inhibition collectively determine MA phenotypes across a broad range of retroviruses and elucidate the significance of their interrelationships, we compared a panel of Gag-leucine zipper constructs (GagLZ) containing MA of different retroviruses. We found that in vitro membrane binding of GagLZ via HIV-1 MA and Rous sarcoma virus (RSV) MA is both PI(4,5)P2 dependent and susceptible to RNA-mediated inhibition. The PM-specific localization and virus-like particle (VLP) release of these GagLZ proteins are severely impaired by overexpression of a PI(4,5)P2-depleting enzyme, polyphosphoinositide 5-phosphatase IV (5ptaseIV). In contrast, membrane binding of GagLZ constructs that contain human T-lymphotropic virus type 1 (HTLV-1) MA, murine leukemia virus (MLV) MA, and human endogenous retrovirus K (HERV-K) MA is PI(4,5)P2 independent and not blocked by RNA. The PM localization and VLP release of these GagLZ chimeras were much less sensitive to 5ptaseIV expression. Notably, single amino acid substitutions that confer a large basic patch rendered HTLV-1 MA susceptible to the RNA-mediated block, suggesting that RNA readily blocks MA containing a large basic patch, such as HIV-1 and RSV MA. Further analyses of these MA mutants suggest a possibility that HIV-1 and RSV MA acquired PI(4,5)P2 dependence to alleviate the membrane binding block imposed by RNA. IMPORTANCE MA basic residues in the HIV-1 structural protein Gag interact with phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P2] and RNA. RNA inhibits HIV-1 MA binding to non-PI(4,5)P2 acidic lipids. This inhibition may promote PM specificity of Gag membrane binding, an early essential step in virus assembly. However, whether and how relationships between these interactions have developed among retroviruses are poorly understood. In this study, by comparing diverse retroviral MA domains, we elucidated a strong correlation among PI(4,5)P2 dependence, susceptibility to RNA-mediated inhibition, and cellular behaviors of Gag. Mutagenesis analyses suggest that a large basic patch on MA is sufficient to confer susceptibility to RNA-mediated inhibition but not for PI(4,5)P2-dependent membrane binding. Our findings highlight RNA's role as a general blocker of large basic patches and suggest a possibility that some retroviruses, including HIV-1, have evolved to bind PI(4,5)P2, while others have adopted smaller basic patches on their MA domains, to overcome the RNA-mediated restriction of membrane binding.
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Affiliation(s)
- Jingga Inlora
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - David R Collins
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Marc E Trubin
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Ji Yeon J Chung
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Akira Ono
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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Olety B, Ono A. Roles played by acidic lipids in HIV-1 Gag membrane binding. Virus Res 2014; 193:108-15. [PMID: 24998886 PMCID: PMC4252750 DOI: 10.1016/j.virusres.2014.06.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2014] [Revised: 06/18/2014] [Accepted: 06/23/2014] [Indexed: 10/25/2022]
Abstract
The MA domain mediates plasma membrane (PM) targeting of HIV-1 Gag, leading to particle assembly at the PM. The interaction between MA and acidic phospholipids, in addition to N-terminal myristoyl moiety, promotes Gag binding to lipid membranes. Among acidic phospholipids, PI(4,5)P2, a PM-specific phosphoinositide, is essential for proper HIV-1 Gag localization to the PM and efficient virus particle production. Recent studies further revealed that MA-bound RNA negatively regulates HIV-1 Gag membrane binding and that PI(4,5)P2 is necessary to overcome this RNA-imposed block. In this review, we will summarize the current understanding of Gag-membrane interactions and discuss potential roles played by acidic phospholipids.
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Affiliation(s)
- Balaji Olety
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, United States
| | - Akira Ono
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, United States.
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Basic motifs target PSGL-1, CD43, and CD44 to plasma membrane sites where HIV-1 assembles. J Virol 2014; 89:454-67. [PMID: 25320329 DOI: 10.1128/jvi.02178-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED HIV-1 incorporates various host membrane proteins during particle assembly at the plasma membrane; however, the mechanisms mediating this incorporation process remain poorly understood. We previously showed that the HIV-1 structural protein Gag localizes to the uropod, a rear-end structure of polarized T cells, and that assembling Gag copatches with a subset, but not all, of the uropod-directed proteins, i.e., PSGL-1, CD43, and CD44, in nonpolarized T cells. The latter observation suggests the presence of a mechanism promoting virion incorporation of these cellular proteins. To address this possibility and identify molecular determinants, in the present study we examined coclustering between Gag and the transmembrane proteins in T and HeLa cells using quantitative two-color superresolution localization microscopy. Consistent with the findings of the T-cell copatching study, we found that basic residues within the matrix domain of Gag are required for Gag-PSGL-1 coclustering. Notably, the presence of a polybasic sequence in the PSGL-1 cytoplasmic domain significantly enhanced this coclustering. We also found that polybasic motifs present in the cytoplasmic tails of CD43 and CD44 also promote their coclustering with Gag. ICAM-1 and ICAM-3, uropod-directed proteins that do not copatch with Gag in T cells, and CD46, a non-uropod-directed protein, showed no or little coclustering with Gag. However, replacing their cytoplasmic tails with the cytoplasmic tail of PSGL-1 significantly enhanced their coclustering with Gag. Altogether, these results identify a novel mechanism for host membrane protein association with assembling HIV-1 Gag in which polybasic sequences present in the cytoplasmic tails of the membrane proteins and in Gag are the major determinants. IMPORTANCE Nascent HIV-1 particles incorporate many host plasma membrane proteins during assembly. However, it is largely unknown what mechanisms promote the association of these proteins with virus assembly sites within the plasma membrane. Notably, our previous study showed that HIV-1 structural protein Gag colocalizes with a group of uropod-directed transmembrane proteins, PSGL-1, CD43, and CD44, at the plasma membrane of T cells. The results obtained in the current study using superresolution localization microscopy suggest the presence of a novel molecular mechanism promoting the association of PSGL-1, CD43, and CD44 with assembling HIV-1 which relies on polybasic sequences in HIV-1 Gag and in cytoplasmic domains of the transmembrane proteins. This information advances our understanding of virion incorporation of host plasma membrane proteins, some of which modulate virus spread positively or negatively, and suggests a possible new strategy to enrich HIV-1-based lentiviral vectors with a desired transmembrane protein.
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Mariani C, Desdouits M, Favard C, Benaroch P, Muriaux DM. Role of Gag and lipids during HIV-1 assembly in CD4(+) T cells and macrophages. Front Microbiol 2014; 5:312. [PMID: 25009540 PMCID: PMC4069574 DOI: 10.3389/fmicb.2014.00312] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 06/08/2014] [Indexed: 12/25/2022] Open
Abstract
HIV-1 is an RNA enveloped virus that preferentially infects CD4+ T lymphocytes and also macrophages. In CD4+ T cells, HIV-1 mainly buds from the host cell plasma membrane. The viral Gag polyprotein targets the plasma membrane and is the orchestrator of the HIV assembly as its expression is sufficient to promote the formation of virus-like particles carrying a lipidic envelope derived from the host cell membrane. Certain lipids are enriched in the viral membrane and are thought to play a key role in the assembly process and the envelop composition. A large body of work performed on infected CD4+ T cells has provided important knowledge about the assembly process and the membrane virus lipid composition. While HIV assembly and budding in macrophages is thought to follow the same general Gag-driven mechanism as in T-lymphocytes, the HIV cycle in macrophage exhibits specific features. In these cells, new virions bud from the limiting membrane of seemingly intracellular compartments, where they accumulate while remaining infectious. These structures are now often referred to as Virus Containing Compartments (VCCs). Recent studies suggest that VCCs represent intracellularly sequestered regions of the plasma membrane, but their precise nature remains elusive. The proteomic and lipidomic characterization of virions produced by T cells or macrophages has highlighted the similarity between their composition and that of the plasma membrane of producer cells, as well as their enrichment in acidic lipids, some components of raft lipids and in tetraspanin-enriched microdomains. It is likely that Gag promotes the coalescence of these components into an assembly platform from which viral budding takes place. How Gag exactly interacts with membrane lipids and what are the mechanisms involved in the interaction between the different membrane nanodomains within the assembly platform remains unclear. Here we review recent literature regarding the role of Gag and lipids on HIV-1 assembly in CD4+ T cells and macrophages.
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Affiliation(s)
- Charlotte Mariani
- Membrane Domains and Viral Assembly, CNRS UMR-5236, Centre d'étude d'agents Pathogènes et Biotechnologies pour la Santé Montpellier, Cedex, France
| | - Marion Desdouits
- Intracellular Transport and Immunity, Immunité et Cancer, Institut Curie - Inserm U932 Paris, France
| | - Cyril Favard
- Membrane Domains and Viral Assembly, CNRS UMR-5236, Centre d'étude d'agents Pathogènes et Biotechnologies pour la Santé Montpellier, Cedex, France
| | - Philippe Benaroch
- Intracellular Transport and Immunity, Immunité et Cancer, Institut Curie - Inserm U932 Paris, France
| | - Delphine M Muriaux
- Membrane Domains and Viral Assembly, CNRS UMR-5236, Centre d'étude d'agents Pathogènes et Biotechnologies pour la Santé Montpellier, Cedex, France
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41
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Murine leukemia virus Gag localizes to the uropod of migrating primary lymphocytes. J Virol 2014; 88:10541-55. [PMID: 24965475 DOI: 10.1128/jvi.01104-14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED B and CD4(+) T lymphocytes are natural targets of murine leukemia virus (MLV). Migrating lymphocytes adopt a polarized morphology with a trailing edge designated the uropod. Here, we demonstrate that MLV Gag localizes to the uropod in polarized B cells and CD4(+) T cells. The uropod localization of MLV Gag was dependent on plasma membrane (PM) association and multimerization of Gag but independent of the viral glycoprotein Env. Basic residues in MA that are required for MLV Gag recruitment to virological synapses between HEK293 and XC cells were dispensable for uropod localization in migrating B cells. Ultrastructural studies indicated that both wild-type and basic-residue mutant Gag localized to the outer surface of the PM at the uropod. Late-domain mutant virus particles were seen at the uropod in form of budding-arrested intermediates. Finally, uropods mediated contact between MLV-infected B cells and uninfected T cells to form virological synapses. Our results suggest that MLV, not unlike HIV, accumulates at the uropod of primary lymphocytes to facilitate viral spreading through the formation of uropod-mediated cell-cell contacts. IMPORTANCE Viruses have evolved mechanisms to coordinate their assembly and budding with cell polarity to facilitate their spreading. In this study, we demonstrated that the viral determinants for MLV Gag to localize to the uropod in polarized B cells are distinct from the requirements to localize to virological synapses in transformed cell lines. Basic residues in MA that are required for the Gag localization to virological synapses between HEK293 and XC cells are dispensable for Gag localization to the uropod in primary B cells. Rather, plasma membrane association and capsid-driven multimerization of Gag are sufficient to drive MLV Gag to the uropod. MLV-laden uropods also mediate contacts between MLV-infected B cells and uninfected T cells to form virological synapses. Our results indicate that MLV accumulates at the uropod of primary lymphocytes to facilitate viral spreading through the formation of uropod-mediated cell-cell contacts.
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Alfadhli A, Barklis E. The roles of lipids and nucleic acids in HIV-1 assembly. Front Microbiol 2014; 5:253. [PMID: 24917853 PMCID: PMC4042026 DOI: 10.3389/fmicb.2014.00253] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 05/08/2014] [Indexed: 11/23/2022] Open
Abstract
During HIV-1 assembly, precursor Gag (PrGag) proteins are delivered to plasma membrane (PM) assembly sites, where they are triggered to oligomerize and bud from cells as immature virus particles. The delivery and triggering processes are coordinated by the PrGag matrix (MA) and nucleocapsid (NC) domains. Targeting of PrGag proteins to membranes enriched in cholesterol and phosphatidylinositol-4,5-bisphosphate (PI[4,5]P2) is mediated by the MA domain, which also has been shown to bind both RNA and DNA. Evidence suggests that the nucleic-acid-binding function of MA serves to inhibit PrGag binding to inappropriate intracellular membranes, prior to delivery to the PM. At the PM, MA domains putatively trade RNA ligands for PI(4,5)P2 ligands, fostering high-affinity membrane binding. Triggering of oligomerization, budding, and virus particle release results when NC domains on adjacent PrGag proteins bind to viral RNA, leading to capsid (CA) domain oligomerization. This process leads to the assembly of immature virus shells in which hexamers of membrane-bound MA trimers appear to organize above interlinked CA hexamers. Here, we review the functions of retroviral MA proteins, with an emphasis on the nucleic-acid-binding capability of the HIV-1 MA protein, and its effects on membrane binding.
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Affiliation(s)
- Ayna Alfadhli
- Department of Molecular Microbiology and Immunology, Oregon Health & Sciences University Portland, OR, USA
| | - Eric Barklis
- Department of Molecular Microbiology and Immunology, Oregon Health & Sciences University Portland, OR, USA
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Prchal J, Kroupa T, Ruml T, Hrabal R. Interaction of Mason-Pfizer monkey virus matrix protein with plasma membrane. Front Microbiol 2014; 4:423. [PMID: 24478762 PMCID: PMC3896817 DOI: 10.3389/fmicb.2013.00423] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 12/31/2013] [Indexed: 01/28/2023] Open
Abstract
Budding is the final step of the late phase of retroviral life cycle. It begins with the interaction of Gag precursor with plasma membrane (PM) through its N-terminal domain, the matrix protein (MA). However, single genera of Retroviridae family differ in the way how they interact with PM. While in case of Lentiviruses (e.g., human immunodeficiency virus) the structural polyprotein precursor Gag interacts with cellular membrane prior to the assembly, Betaretroviruses [Mason-Pfizer monkey virus (M-PMV)] first assemble their virus-like particles (VLPs) in the pericentriolar region of the infected cell and therefore, already assembled particles interact with the membrane. Although both these types of retroviruses use similar mechanism of the interaction of Gag with the membrane, the difference in the site of assembly leads to some differences in the mechanism of the interaction. Here we describe the interaction of M-PMV MA with PM with emphasis on the structural aspects of the interaction with single phospholipids.
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Affiliation(s)
- Jan Prchal
- Laboratory of NMR Spectroscopy, Institute of Chemical Technology, Prague Czech Republic
| | - Tomáš Kroupa
- Laboratory of NMR Spectroscopy, Institute of Chemical Technology, Prague Czech Republic ; Department of Biochemistry and Microbiology, Institute of Chemical Technology, Prague Czech Republic
| | - Tomáš Ruml
- Department of Biochemistry and Microbiology, Institute of Chemical Technology, Prague Czech Republic
| | - Richard Hrabal
- Laboratory of NMR Spectroscopy, Institute of Chemical Technology, Prague Czech Republic
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[Membrane Binding of Retroviral Gag Proteins]. Uirusu 2014; 64:155-64. [PMID: 26437838 DOI: 10.2222/jsv.64.155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Location of virus assembly in infected cells has major influences on efficiencies of virus assembly and release and on post-assembly processes including cell-to-cell transmission. Therefore, for better understanding of virus spread and for developing new antiviral strategies, it is important to elucidate mechanisms by which the subcellular site of virus particle assembly is determined. Retrovirus particle assembly is driven by viral structural protein Gag. In the case of HIV-1, Gag binds to the plasma membrane (PM) via the N-terminal MA domain and forms nascent particles at this location. Recent studies reveled that PM-specific phospholipid PI(4,5)P2 plays an important role in directing Gag to the PM through its interaction with MA. In this review, I will summarize our current understanding of relationships between retroviral MA domains and phospholipids in cellular membranes and discuss possible mechanisms by which lipids and other factors regulate membrane binding and subcellular localization of retroviral Gag proteins.
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Effect of multimerization on membrane association of Rous sarcoma virus and HIV-1 matrix domain proteins. J Virol 2013; 87:13598-608. [PMID: 24109216 DOI: 10.1128/jvi.01659-13] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In most retroviruses, plasma membrane (PM) association of the Gag structural protein is a critical step in viral assembly, relying in part on interaction between the highly basic Gag MA domain and the negatively charged inner leaflet of the PM. Assembly is thought to begin with Gag dimerization followed by multimerization, resulting in a hexameric lattice. To directly address the role of multimerization in membrane binding, we fused the MA domains of Rous sarcoma virus (RSV) and HIV-1 to the chemically inducible dimerization domain FK506-binding protein (FKBP) or to the hexameric protein CcmK4 from cyanobacteria. The cellular localization of the resulting green fluorescent protein (GFP)-tagged chimeric proteins was examined by fluorescence imaging, and the association of the proteins with liposomes was quantified by flotation in sucrose gradients, following synthesis in a reticulocyte extract or as purified proteins. Four lipid compositions were tested, representative of liposomes commonly reported in flotation experiments. By themselves, GFP-tagged RSV and HIV-1 MA proteins were largely cytoplasmic, but both hexamerized proteins were highly concentrated at the PM. Dimerization led to partial PM localization for HIV-1 MA. These in vivo effects of multimerization were reproduced in vitro. In flotation analyses, the intact RSV and HIV-1 Gag proteins were more similar to multimerized MA than to monomeric MA. RNA is reported to compete with acidic liposomes for HIV-1 Gag binding, and thus we also examined the effects of RNase treatment or tRNA addition on flotation. tRNA competed with liposomes in the case of some but not all lipid compositions and ionic strengths. Taken together, our results further underpin the model that multimerization is critical for PM association of retroviral Gag proteins. In addition, they suggest that the modulation of membrane binding by RNA, as previously reported for HIV-1, may not hold for RSV.
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One-step separation of myristoylated and nonmyristoylated retroviral matrix proteins. Protein Expr Purif 2013; 92:94-9. [PMID: 24056256 DOI: 10.1016/j.pep.2013.09.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 09/03/2013] [Accepted: 09/06/2013] [Indexed: 11/22/2022]
Abstract
N-terminal myristoylation of retroviral matrix proteins is essential for the targeting of the Gag polyproteins to the plasma membrane. To investigate the effect of the myristoylation on the structure and membrane binding ability of the matrix proteins, it is necessary to prepare their myristoylated forms. We present purification of myristoylated matrix proteins of the mouse mammary tumor virus and murine leukemia virus, two morphogenetically distinct retroviruses. The proteins were expressed in Escherichia coli coexpressing a yeast N-myristoyltransferase. This E. coli expression system yielded a mixture of myristoylated and nonmyristoylated matrix proteins. We established efficient one-step metal affinity purification that enabled to obtain pure myristoylated matrix proteins suitable for structural and functional studies.
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Sundquist WI, Kräusslich HG. HIV-1 assembly, budding, and maturation. Cold Spring Harb Perspect Med 2013; 2:a006924. [PMID: 22762019 DOI: 10.1101/cshperspect.a006924] [Citation(s) in RCA: 514] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A defining property of retroviruses is their ability to assemble into particles that can leave producer cells and spread infection to susceptible cells and hosts. Virion morphogenesis can be divided into three stages: assembly, wherein the virion is created and essential components are packaged; budding, wherein the virion crosses the plasma membrane and obtains its lipid envelope; and maturation, wherein the virion changes structure and becomes infectious. All of these stages are coordinated by the Gag polyprotein and its proteolytic maturation products, which function as the major structural proteins of the virus. Here, we review our current understanding of the mechanisms of HIV-1 assembly, budding, and maturation, starting with a general overview and then providing detailed descriptions of each of the different stages of virion morphogenesis.
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Affiliation(s)
- Wesley I Sundquist
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, USA.
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Serrière J, Robert X, Perez M, Gouet P, Guillon C. Biophysical characterization and crystal structure of the Feline Immunodeficiency Virus p15 matrix protein. Retrovirology 2013; 10:64. [PMID: 23800358 PMCID: PMC3706335 DOI: 10.1186/1742-4690-10-64] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 06/13/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Feline Immunodeficiency Virus (FIV) is a viral pathogen that infects domestic cats and wild felids. During the viral replication cycle, the FIV p15 matrix protein oligomerizes to form a closed matrix that underlies the lipidic envelope of the virion. Because of its crucial role in the early and late stages of viral morphogenesis, especially in viral assembly, FIV p15 is an interesting target in the development of potential new therapeutic strategies. RESULTS Our biochemical study of FIV p15 revealed that it forms a stable dimer in solution under acidic conditions and at high concentration, unlike other retroviral matrix proteins. We determined the crystal structure of full-length FIV p15 to 2 Å resolution and observed a helical organization of the protein, typical for retroviral matrix proteins. A hydrophobic pocket that could accommodate a myristoyl group was identified, and the C-terminal end of FIV p15, which is mainly unstructured, was visible in electron density maps. As FIV p15 crystallizes in acidic conditions but with one monomer in the asymmetric unit, we searched for the presence of a biological dimer in the crystal. No biological assembly was detected by the PISA server, but the three most buried crystallographic interfaces have interesting features: the first one displays a highly conserved tryptophan acting as a binding platform, the second one is located along a 2-fold symmetry axis and the third one resembles the dimeric interface of EIAV p15. Because the C-terminal end of p15 is involved in two of these three interfaces, we investigated the structure and assembly of a C-terminal-truncated form of p15 lacking 14 residues. The truncated FIV p15 dimerizes in solution at a lower concentration and crystallizes with two molecules in the asymmetric unit. The EIAV-like dimeric interface is the only one to be retained in the new crystal form. CONCLUSION The dimeric form of FIV p15 in solution and its extended C-terminal end are characteristic among lentiviral matrix proteins. Crystallographic interfaces revealed several interactions that might be involved in FIV replication. Further studies are needed to better understand their biological relevance in the function of FIV Gag during viral replication.
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Neira JL. Nuclear magnetic resonance spectroscopy to study virus structure. Subcell Biochem 2013; 68:145-76. [PMID: 23737051 DOI: 10.1007/978-94-007-6552-8_5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nuclear magnetic resonance (NMR) is a spectroscopic technique based in the absorption of radiofrequency radiation by atomic nuclei in the presence of an external magnetic field. NMR has followed a "bottom-up" approach to solve the structures of isolated domains of viral proteins, including capsid protein subunits. NMR has been instrumental to describe conformational changes in viral proteins and nucleic acids, showing the presence of dynamic equilibria which are thought to be important at different stages of the virus life cycle; in this sense, NMR is also the only technique currently available to describe, in atomic detail, the conformational preferences of natively unfolded viral proteins. NMR has also complemented X-ray crystallography and has been combined with electron microscopy to obtain pseudo-atomic models of entire virus capsids. Finally, the joint use of liquid and solid-state NMR has allowed the identification of conformational changes in intact viral capsids on insertion in host membranes.
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Affiliation(s)
- José L Neira
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, 03202, Elche, Alicante, Spain,
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Basic residues in the matrix domain and multimerization target murine leukemia virus Gag to the virological synapse. J Virol 2013; 87:7113-26. [PMID: 23616653 DOI: 10.1128/jvi.03263-12] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Murine leukemia virus (MLV) can efficiently spread in tissue cultures by polarizing assembly to virological synapses. The viral envelope glycoprotein (Env) establishes cell-cell contacts and subsequently recruits Gag by a process that depends on its cytoplasmic tail. MLV Gag is recruited to virological synapses through the matrix domain (MA) (J. Jin, F. Li, and W. Mothes, J. Virol. 85:7672-7682, 2011). However, how MA targets Gag to sites of cell-cell contact remains unknown. Here we report that basic residues within MA are critical for directing MLV Gag to virological synapses. Alternative membrane targeting domains (MTDs) containing multiple basic residues can efficiently substitute MA to direct polarized assembly. Similarly, mutations in the polybasic cluster of MA that disrupt Gag polarization can be rescued by N-terminal addition of MTDs containing basic residues. MTDs containing basic residues alone fail to be targeted to the virological synapse. Systematic deletion experiments reveal that domains within Gag known to mediate Gag multimerization are also required. Thus, our data predict the existence of a specific "acidic" interface at virological synapses that mediates the recruitment of MLV Gag via the basic cluster of MA and Gag multimerization.
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