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Sumner C, Ono A. Relationship between HIV-1 Gag Multimerization and Membrane Binding. Viruses 2022; 14:v14030622. [PMID: 35337029 PMCID: PMC8949992 DOI: 10.3390/v14030622] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/06/2022] [Accepted: 03/09/2022] [Indexed: 12/11/2022] Open
Abstract
HIV-1 viral particle assembly occurs specifically at the plasma membrane and is driven primarily by the viral polyprotein Gag. Selective association of Gag with the plasma membrane is a key step in the viral assembly pathway, which is traditionally attributed to the MA domain. MA regulates specific plasma membrane binding through two primary mechanisms including: (1) specific interaction of the MA highly basic region (HBR) with the plasma membrane phospholipid phosphatidylinositol (4,5) bisphosphate [PI(4,5)P2], and (2) tRNA binding to the MA HBR, which prevents Gag association with non-PI(4,5)P2 containing membranes. Gag multimerization, driven by both CA–CA inter-protein interactions and NC-RNA binding, also plays an essential role in viral particle assembly, mediating the establishment and growth of the immature Gag lattice on the plasma membrane. In addition to these functions, the multimerization of HIV-1 Gag has also been demonstrated to enhance its membrane binding activity through the MA domain. This review provides an overview of the mechanisms regulating Gag membrane binding through the MA domain and multimerization through the CA and NC domains, and examines how these two functions are intertwined, allowing for multimerization mediated enhancement of Gag membrane binding.
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2
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A splicing factor phosphorylated by protein kinase A is increased in HL60 cells treated with retinoic acid. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1869:119142. [PMID: 34599982 DOI: 10.1016/j.bbamcr.2021.119142] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/18/2021] [Accepted: 09/27/2021] [Indexed: 11/22/2022]
Abstract
Retinoic acid (RA) induces the differentiation of human promyelocytic leukemia HL60 cells into granulocytic cells and inhibits proliferation. Certain of actions of RA are mediated by RA nuclear receptors that regulate gene expression. However, it is also known that direct protein modification by RA (retinoylation) can occur. One such retinoylated protein in HL60 cells is a regulatory subunit of protein kinase A (PKA), which is increased in the nucleus following RA treatment and which then increases phosphorylation of other nuclear proteins. However, a complete understanding of which nuclear proteins are phosphorylated is lacking. In the current study, we employed mass spectrometry to identify one of the PKA-phosphorylated proteins as a serine/arginine-rich splicing factor 1 (SF2, SRSF1). We found that RA treatment increased the level of PKA-phosphorylated SF2 but decreased the level of SF2. While SF2 regulates myelogenous cell leukemia-1 (Mcl-1, anti-apoptotic factor), RA treatment reduced the level of Mcl-1L (full-length Mcl-1 long) and increased the level of Mcl-1S (Mcl-1 short; a short splicing variant of the Mcl-1). Furthermore, treatment with a PKA inhibitor reversed these effects on Mcl-1 and inhibited RA-induced cell differentiation. In contrast, treatment with a Mcl-1L inhibitor enhanced RA-induced cell differentiation. These results indicate that RA activates PKA in the nucleus, increases phosphorylation of SF2, raises levels of Mcl-1S and lowers levels of Mcl-1L, resulting in the induction of differentiation. RA-modified PKA may play an important role in inducing cell differentiation and suppressing cell proliferation.
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3
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Sarni S, Biswas B, Liu S, Olson ED, Kitzrow JP, Rein A, Wysocki VH, Musier-Forsyth K. HIV-1 Gag protein with or without p6 specifically dimerizes on the viral RNA packaging signal. J Biol Chem 2020; 295:14391-14401. [PMID: 32817318 DOI: 10.1074/jbc.ra120.014835] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 08/10/2020] [Indexed: 02/04/2023] Open
Abstract
The HIV-1 Gag protein is responsible for genomic RNA (gRNA) packaging and immature viral particle assembly. Although the presence of gRNA in virions is required for viral infectivity, in its absence, Gag can assemble around cellular RNAs and form particles resembling gRNA-containing particles. When gRNA is expressed, it is selectively packaged despite the presence of excess host RNA, but how it is selectively packaged is not understood. Specific recognition of a gRNA packaging signal (Psi) has been proposed to stimulate the efficient nucleation of viral assembly. However, the heterogeneity of Gag-RNA interactions renders capturing this transient nucleation complex using traditional structural biology approaches challenging. Here, we used native MS to investigate RNA binding of wild-type (WT) Gag and Gag lacking the p6 domain (GagΔp6). Both proteins bind to Psi RNA primarily as dimers, but to a control RNA primarily as monomers. The dimeric complexes on Psi RNA require an intact dimer interface within Gag. GagΔp6 binds to Psi RNA with high specificity in vitro and also selectively packages gRNA in particles produced in mammalian cells. These studies provide direct support for the idea that Gag binding to Psi specifically promotes nucleation of Gag-Gag interactions at the early stages of immature viral particle assembly in a p6-independent manner.
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Affiliation(s)
- Samantha Sarni
- Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio, USA.,Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, Ohio, USA.,Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA
| | - Banhi Biswas
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Shuohui Liu
- Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA.,Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
| | - Erik D Olson
- Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio, USA.,Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA.,Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
| | - Jonathan P Kitzrow
- Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio, USA.,Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA.,Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
| | - Alan Rein
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Vicki H Wysocki
- Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio, USA .,Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, Ohio, USA.,Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Karin Musier-Forsyth
- Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio, USA .,Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, USA.,Center for Retrovirus Research, The Ohio State University, Columbus, Ohio, USA
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4
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Krishnakumari V, Guru A, Adicherla H, Nagaraj R. Effects of increasing hydrophobicity by N‐terminal myristoylation on the antibacterial and hemolytic activities of the C‐terminal cationic segments of human‐β‐defensins 1–3. Chem Biol Drug Des 2018; 92:1504-1513. [DOI: 10.1111/cbdd.13317] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 01/03/2018] [Accepted: 01/20/2018] [Indexed: 12/26/2022]
Affiliation(s)
| | - Ankeeta Guru
- CSIR‐ Center for Cellular and Molecular Biology Hyderabad India
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5
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Peng T, Hang HC. Chemical Proteomic Profiling of Protein Fatty-Acylation in Microbial Pathogens. Curr Top Microbiol Immunol 2018; 420:93-110. [PMID: 30128826 DOI: 10.1007/82_2018_126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Protein fatty-acylation describes the covalent modification of protein with fatty acids during or after translation. Chemical proteomic profiling methods have provided new opportunities to explore protein fatty-acylation in microbial pathogens. Recent studies suggest that protein fatty-acylation is essential to survival and pathogenesis of eukaryotic pathogens such as parasites and fungi. Moreover, fatty-acylation in host cells can be exploited or manipulated by pathogenic bacteria. Herein, we first review the prevalent classes of fatty-acylation in microbial pathogens and the chemical proteomic profiling methods for their global analysis. We then summarize recent fatty-acylation profiling studies performed in eukaryotic pathogens and during bacterial infections, highlighting how they contribute to functional characterization of fatty-acylation under these contexts.
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Affiliation(s)
- Tao Peng
- State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, China.
| | - Howard C Hang
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, New York, NY, 10065, USA.
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6
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Retinoylation (covalent modification by retinoic acid) of Rho-GDIβ in the human myeloid leukemia cell line HL60 and its functional significance. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:2011-2019. [DOI: 10.1016/j.bbalip.2016.10.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 10/03/2016] [Accepted: 10/05/2016] [Indexed: 11/20/2022]
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7
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Di Pisa M, Chassaing G, Swiecicki JM. When cationic cell-penetrating peptides meet hydrocarbons to enhance in-cell cargo delivery. J Pept Sci 2015; 21:356-69. [PMID: 25787823 DOI: 10.1002/psc.2755] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 12/30/2014] [Accepted: 01/07/2015] [Indexed: 01/03/2023]
Abstract
Cell-penetrating peptides (CPPs) are short sequences often rich in cationic residues with the remarkable ability to cross cell membranes. In the past 20 years, CPPs have gained wide interest and have found numerous applications in the delivery of bioactive cargoes to the cytosol and even the nucleus of living cells. The covalent or non-covalent addition of hydrocarbon moieties to cationic CPPs alters the hydrophobicity/hydrophilicity balance in their sequence. Such perturbation dramatically influences their interaction with the cell membrane, might induce self-assembling properties and modifies their intracellular trafficking. In particular, the introduction of lipophilic moieties changes the subcellular distribution of CPPs and might result in a dramatically increase of the internalization yield of the co-transported cargoes. Herein, we offer an overview of different aspects of the recent findings concerning the properties of CPPs covalently or non-covalently associated to hydrocarbons. We will focus on the impact of the hydrocarbon moieties on the delivery of various cargoes, either covalently or non-covalently bound to the modified CPPs. We will also provide some key elements to rationalize the influence of the hydrocarbons moieties on the cellular uptake. Furthermore, the recent in vitro and in vivo successful applications of acylated CPPs will be summarized to provide a broad view of the versatility of these modified CPPs as small-molecules and oligonucleotides vectors.
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Affiliation(s)
- Margherita Di Pisa
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7203, Laboratoire des Biomolécules, Paris, F-75005, France; CNRS, UMR 7203, Laboratoire des Biomolécules, Paris, F-75005, France; Ecole Normale Supérieure (ENS), UMR 7203, Laboratoire des Biomolécules, Département de Chimie, 24 Rue Lhomond, Paris, F-75005, France
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8
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Ochi A, Abe T, Nakao R, Yamamoto Y, Kitahata K, Takagi M, Hirasaka K, Ohno A, Teshima-Kondo S, Taesik G, Choi I, Kawamura T, Nemoto H, Mukai R, Terao J, Nikawa T. N-myristoylated ubiquitin ligase Cbl-b inhibitor prevents on glucocorticoid-induced atrophy in mouse skeletal muscle. Arch Biochem Biophys 2015; 570:23-31. [PMID: 25689493 DOI: 10.1016/j.abb.2015.02.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 01/16/2015] [Accepted: 02/06/2015] [Indexed: 12/12/2022]
Abstract
A DGpYMP peptide mimetic of tyrosine(608)-phosphorylated insulin receptor substrate-1 (IRS-1), named Cblin, was previously shown to significantly inhibit Cbl-b-mediated IRS-1 ubiquitination. In the present study, we developed N-myristoylated Cblin and investigated whether it was effective in preventing glucocorticoid-induced muscle atrophy. Using HEK293 cells overexpressing Cbl-b, IRS-1 and ubiquitin, we showed that the 50% inhibitory concentrations of Cbl-b-mediated IRS-1 ubiquitination by N-myristoylated Cblin and Cblin were 30 and 120 μM, respectively. Regarding the DEX-induced atrophy of C2C12 myotubes, N-myristoylated Cblin was more effective than Cblin for inhibiting the DEX-induced decreases in C2C12 myotube diameter and IRS-1 degradation. The inhibitory efficacy of N-myristoylated Cblin on IRS-1 ubiquitination in C2C12 myotubes was approximately fourfold larger than that of Cblin. Furthermore, N-myristoylation increased the incorporation of Cblin into HEK293 cells approximately 10-folds. Finally, we demonstrated that N-myristoylated Cblin prevented the wet weight loss, IRS-1 degradation, and MAFbx/atrogin-1 and MuRF-1 expression in gastrocnemius muscle of DEX-treated mice approximately fourfold more effectively than Cblin. Taken together, these results suggest that N-myristoylated Cblin prevents DEX-induced skeletal muscle atrophy in vitro and in vivo, and that N-myristoylated Cblin more effectively prevents muscle atrophy than unmodified Cblin.
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Affiliation(s)
- Arisa Ochi
- Department of Nutritional Physiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan
| | - Tomoki Abe
- Department of Nutritional Physiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan
| | - Reiko Nakao
- Department of Nutritional Physiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan; National Institute of Advanced Industrial Science and Technology, Ibaraki 305-8566, Japan
| | - Yoriko Yamamoto
- Department of Nutritional Physiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan
| | - Kanako Kitahata
- Department of Nutritional Physiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan
| | - Marina Takagi
- Department of Nutritional Physiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan
| | - Katsuya Hirasaka
- Department of Nutritional Physiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan
| | - Ayako Ohno
- Department of Nutritional Physiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan
| | - Shigetada Teshima-Kondo
- Department of Nutritional Physiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan
| | - Gwag Taesik
- Division of Biological Science and Technology, College of Science and Technology, Yonsei University, Yonsei, Republic of Korea
| | - Inho Choi
- Division of Biological Science and Technology, College of Science and Technology, Yonsei University, Yonsei, Republic of Korea
| | - Tomoyuki Kawamura
- Department of Pharmaceutical Chemistry, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan
| | - Hisao Nemoto
- Department of Pharmaceutical Chemistry, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan
| | - Rie Mukai
- Department of Food Science, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan
| | - Junji Terao
- Department of Food Science, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan
| | - Takeshi Nikawa
- Department of Nutritional Physiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan.
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9
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Yin F, Wang M, Tan Y, Deng F, Vlak JM, Hu Z, Wang H. Identification and functional analysis of inter-subunit disulfide bonds of the F protein of Helicoverpa armigera nucleopolyhedrovirus. J Gen Virol 2014; 95:2820-2830. [PMID: 25114029 DOI: 10.1099/vir.0.068122-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The major envelope fusion protein F of the budded virus of baculoviruses consists of two disulfide-linked subunits: an N-terminal F2 subunit and a C-terminal, membrane-anchored F1 subunit. There is one cysteine in F2 and there are 15 cysteines in F1, but their role in disulfide linking is largely unknown. In this study, the inter- and intra-subunit disulfide bonds of the Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus (HearNPV) F protein were analysed by site-directed mutagenesis. Results indicated that in a functional F protein, an inter-subunit disulfide bond exists between amino acids C108 (F2) and C241 (F1). When C241 was mutated, an alternative disulfide bond was formed between C108 and C232, rendering F non-functional. No inter-subunit bridge was observed in a double C232/C241 mutant of F1. C403 was not involved in the formation of inter-subunit disulfide bonding, but mutation of this amino acid decreased viral infectivity significantly, suggesting that it might be involved in intra-subunit disulfide bonds. The influence of reductant [tris(2-carboxyethyl) phosphine (TCEP)] and free-thiol inhibitors [4-acetamido-4'-maleimidylstilbene 2,2'-disulfonic acid (AMS) and 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB)] on the infectivity of HearNPV was tested. The results indicated that TCEP greatly decreased the infection of HzAm1 cells by HearNPV. In contrast, AMS and DTNB had no inhibitory effect on viral infectivity. The data suggested that free thiol/disulfide isomerization was not likely to play a role in viral entry and infectivity.
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Affiliation(s)
- Feifei Yin
- School of Tropical and Laboratory Medicine, Hainan Medical University, Haikou 571101, PR China.,State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences (CAS), Wuhan 430071, PR China
| | - Manli Wang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences (CAS), Wuhan 430071, PR China
| | - Ying Tan
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences (CAS), Wuhan 430071, PR China
| | - Fei Deng
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences (CAS), Wuhan 430071, PR China
| | - Just M Vlak
- Laboratory of Virology, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Zhihong Hu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences (CAS), Wuhan 430071, PR China
| | - Hualin Wang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences (CAS), Wuhan 430071, PR China
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10
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Cytoplasmic polyhedrosis virus-induced differential gene expression in two silkworm strains of different susceptibility. Gene 2014; 539:230-7. [DOI: 10.1016/j.gene.2014.01.073] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 01/14/2014] [Accepted: 01/27/2014] [Indexed: 01/02/2023]
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11
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Acyl Transfer from Membrane Lipids to Peptides Is a Generic Process. J Mol Biol 2013; 425:4379-87. [DOI: 10.1016/j.jmb.2013.07.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 06/24/2013] [Accepted: 07/10/2013] [Indexed: 12/24/2022]
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12
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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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Mahajan M, Bhattacharjya S. β-Hairpin peptides: heme binding, catalysis, and structure in detergent micelles. Angew Chem Int Ed Engl 2013; 52:6430-4. [PMID: 23640811 DOI: 10.1002/anie.201300241] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 03/25/2013] [Indexed: 11/11/2022]
Affiliation(s)
- Mukesh Mahajan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
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Mahajan M, Bhattacharjya S. β-Hairpin Peptides: Heme Binding, Catalysis, and Structure in Detergent Micelles. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201300241] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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15
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Alterations in the MA and NC domains modulate phosphoinositide-dependent plasma membrane localization of the Rous sarcoma virus Gag protein. J Virol 2013; 87:3609-15. [PMID: 23325682 DOI: 10.1128/jvi.03059-12] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Retroviral Gag proteins direct virus particle assembly from the plasma membrane (PM). Phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P(2)] plays a role in PM targeting of several retroviral Gag proteins. Here we report that depletion of intracellular PI(4,5)P(2) and phosphatidylinositol-(3,4,5)-triphosphate [PI(3,4,5)P(3)] levels impaired Rous sarcoma virus (RSV) Gag PM localization. Gag mutants deficient in nuclear trafficking were less sensitive to reduction of intracellular PI(4,5)P(2) and PI(3,4,5)P(3), suggesting a possible connection between Gag nuclear trafficking and phosphoinositide-dependent PM targeting.
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16
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Blacklaws BA. Small ruminant lentiviruses: immunopathogenesis of visna-maedi and caprine arthritis and encephalitis virus. Comp Immunol Microbiol Infect Dis 2012; 35:259-69. [PMID: 22237012 DOI: 10.1016/j.cimid.2011.12.003] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2011] [Revised: 12/08/2011] [Accepted: 12/09/2011] [Indexed: 10/14/2022]
Abstract
The small ruminant lentiviruses include the prototype for the genus, visna-maedi virus (VMV) as well as caprine arthritis encephalitis virus (CAEV). Infection of sheep or goats with these viruses causes slow, progressive, inflammatory pathology in many tissues, but the most common clinical signs result from pathology in the lung, mammary gland, central nervous system and joints. This review examines replication, immunity to and pathogenesis of these viruses and highlights major differences from and similarities to some of the other lentiviruses.
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Affiliation(s)
- Barbara A Blacklaws
- Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, UK.
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17
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Unconventional myristoylation of large-conductance Ca²⁺-activated K⁺ channel (Slo1) via serine/threonine residues regulates channel surface expression. Proc Natl Acad Sci U S A 2011; 108:10744-9. [PMID: 21670298 DOI: 10.1073/pnas.1008863108] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Protein myristoylation is a means by which cells anchor proteins into membranes. The most common type of myristoylation occurs at an N-terminal glycine. However, myristoylation rarely occurs at an internal amino acid residue. Here we tested whether the α-subunit of the human large-conductance voltage- and Ca(2+)-activated K(+) channel (hSlo1) might undergo internal myristoylation. hSlo1 expressed in HEK293T cells incorporated [(3)H]myristic acid via a posttranslational mechanism, which is insensitive to cycloheximide, an inhibitor of protein biosynthesis. In-gel hydrolysis of [(3)H]myristoyl-hSlo1 with alkaline NH(2)OH (which cleaves hydroxyesters) but not neutral NH(2)OH (which cleaves thioesters) completely removed [(3)H]myristate from hSlo1, suggesting the involvement of a hydroxyester bond between hSlo1's hydroxyl-bearing serine, threonine, and/or tyrosine residues and myristic acid; this type of esterification was further confirmed by its resistance to alkaline Tris·HCl. Treatment of cells expressing hSlo1 with 100 μM myristic acid caused alteration of hSlo1 activation kinetics and a 40% decrease in hSlo1 current density from 20 to 12 nA*MΩ. Immunocytochemistry confirmed a decrease in hSlo1 plasmalemma localization by myristic acid. Replacement of the six serines or the seven threonines (but not of the single tyrosine) of hSlo1 intracellular loops 1 and 3 with alanines decreased hSlo1 direct myristoylation by 40-44%, whereas in combination decreased myristoylation by nearly 90% and abolished the myristic acid-induced change in current density. Our data demonstrate that an ion channel, hSlo1, is internally and posttranslationally myristoylated. Myristoylation occurs mainly at hSlo1 intracellular loop 1 or 3, and is an additional mechanism for channel surface expression regulation.
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Serebryakova MV, Demina IA, Galyamina MA, Kondratov IG, Ladygina VG, Govorun VM. The acylation state of surface lipoproteins of mollicute Acholeplasma laidlawii. J Biol Chem 2011; 286:22769-76. [PMID: 21540185 DOI: 10.1074/jbc.m111.231316] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Acylation of the N-terminal Cys residue is an essential, ubiquitous, and uniquely bacterial posttranslational modification that allows anchoring of proteins to the lipid membrane. In gram-negative bacteria, acylation proceeds through three sequential steps requiring lipoprotein diacylglyceryltransferase, lipoprotein signal peptidase, and finally lipoprotein N-acyltransferase. The apparent lack of genes coding for recognizable homologs of lipoprotein N-acyltransferase in gram-positive bacteria and Mollicutes suggests that the final step of the protein acylation process may be absent in these organisms. In this work, we monitored the acylation state of eight major lipoproteins of the mollicute Acholeplasma laidlawii using a combination of standard two-dimensional gel electrophoresis protein separation, blotting to nitrocellulose membranes, and MALDI-MS identification of modified N-terminal tryptic peptides. We show that for each A. laidlawii lipoprotein studied a third fatty acid in an amide linkage on the N-terminal Cys residue is present, whereas diacylated species were not detected. The result thus proves that A. laidlawii encodes a lipoprotein N-acyltransferase activity. We hypothesize that N-acyltransferases encoded by genes non-homologous to N-acyltransferases of gram-negative bacteria are also present in other mollicutes and gram-positive bacteria.
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Affiliation(s)
- Marina V Serebryakova
- Institute of Physico-Chemical Medicine, Federal Medico-Biological Agency, Moscow 119992, Russia.
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19
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Forrester MT, Hess DT, Thompson JW, Hultman R, Moseley MA, Stamler JS, Casey PJ. Site-specific analysis of protein S-acylation by resin-assisted capture. J Lipid Res 2010; 52:393-8. [PMID: 21044946 DOI: 10.1194/jlr.d011106] [Citation(s) in RCA: 252] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protein S-acylation is a major posttranslational modification whereby a cysteine thiol is converted to a thioester. A prototype is S-palmitoylation (fatty acylation), in which a protein undergoes acylation with a hydrophobic 16 carbon lipid chain. Although this modification is a well-recognized determinant of protein function and localization, current techniques to study cellular S-acylation are cumbersome and/or technically demanding. We recently described a simple and robust methodology to rapidly identify S-nitrosylation sites in proteins via resin-assisted capture (RAC) and provided an initial description of the applicability of the technique to S-acylated proteins (acyl-RAC). Here we expand on the acyl-RAC assay, coupled with mass spectrometry-based proteomics, to characterize both previously reported and novel sites of endogenous S-acylation. Acyl-RAC should therefore find general applicability in studies of both global and individual protein S-acylation in mammalian cells.
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Affiliation(s)
- Michael T Forrester
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
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20
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Takahashi N, Ohba T. Demonstration of basic proteins that bind retinoic acid in the human myeloid leukemia cell line HL60. Biol Pharm Bull 2010; 32:1943-6. [PMID: 19881315 DOI: 10.1248/bpb.32.1943] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Retinoic acid (RA) has a variety of biological effects in mammalian cells and tissues. It is well known that RA is a potent anticancer agent that induces differentiation of leukemia cells as well as inhibiting cell growth. The current study examined HL60 proteins using anti-RA monoclonal antibodies (ARMAs) and found that some RA-binding proteins may be histones. These proteins eluted in the void volume fractions following Mono Q anion exchange chromatography and immunostained with ARMAs. These ARMAs showed specific binding to the proteins in a saturable manner that depended on antibody concentration. Certain of these proteins co-migrated with histones on one-dimensional polyacrylamide gel electrophoresis. It was also found that histones isolated from HL60 cells treated with RA also immunostained with ARMAs. These results indicate that basic proteins, including histones, may be bound to RA covalently in HL60 cells and that RA-binding histones may play significant roles in the transcriptional regulation of genes by RA.
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Affiliation(s)
- Noriko Takahashi
- Laboratory of Physiological Chemistry, Institute of Medicinal Chemistry, Hoshi University, Shinagawa, Tokyo 142-8501, Japan.
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Influence of all-trans-retinoic acid on oxoglutarate carrier via retinoylation reaction. Biochim Biophys Acta Mol Cell Biol Lipids 2008; 1791:3-7. [PMID: 18977311 DOI: 10.1016/j.bbalip.2008.09.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Revised: 09/17/2008] [Accepted: 09/24/2008] [Indexed: 11/21/2022]
Abstract
All-trans-retinoic acid (atRA), an activated metabolite of vitamin A, is incorporated covalently into proteins both invivo and invitro. AtRA reduced the transport activity of the oxoglutarate carrier (OGC) isolated from testes mitochondria to 58% of control via retinoylation reaction. Labeling of testes mitochondrial proteins with (3)HatRA demonstrated the binding of atRA to a 31.5 KDa protein. This protein was identified as OGC due to the competition for the labeling reaction with 2-oxoglutarate, the specific OGC substrate. The role of retinoylated proteins is currently being explored and here we have the first evidence that retinoic acids bind directly to OGC and inhibit its activity in rat testes mitochondria via retinoylation reaction. This study indicates the evidence of a specific interaction between atRA and OGC and establishes a novel mechanism for atRA action, which could influence the physiological biosynthesis of testosterone in situations such as retinoic acid treatment.
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23
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Tucci P, Cione E, Genchi G. Retinoic acid-induced testosterone production and retinoylation reaction are concomitant and exhibit a positive correlation in Leydig (TM-3) cells. J Bioenerg Biomembr 2008; 40:111-5. [PMID: 18324454 DOI: 10.1007/s10863-008-9132-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Accepted: 02/11/2008] [Indexed: 10/22/2022]
Abstract
Retinoic acid (RA) exerts diverse biological effects in the control of cell growth in embryogenesis and oncogenesis. The effects of RA are thought to be mediated by the nuclear retinoid receptors; however, not all the effects of RA can be explained by the nuclear receptor pathways. Indeed, retinoylation is another mechanism of action elicited by RA. In growing TM-3 Leydig cell cultures, the extent of retinoylation depends in a saturable manner on the initial concentration of 3H-RA, time and cell number. In addition, dose-response curves for RA-induced testosterone production and retinoylation are concomitant and exhibit a positive correlation. In the present study we demonstrate that RA is able to influence a retinoylation reaction on protein(s) probably involved on steroidogenesis.
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Affiliation(s)
- Paola Tucci
- Dipartimento Farmaco-Biologico, Laboratorio di Biochimica, Edificio Polifunzionale, Università della Calabria, 87036 Rende, CS, Italy
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24
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Xie B, Luo X, Zhao C, Priest CM, Chan SY, O’ Connor PB, Kirschner DA, Costello CE. Molecular Characterization of Myelin Protein Zero in Xenopus laevis Peripheral Nerve: Equilibrium between Non-covalently Associated Dimer and Monomer. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2007; 268:304-315. [PMID: 19430539 PMCID: PMC2678737 DOI: 10.1016/j.ijms.2007.08.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Myelin protein zero (P0), a glycosylated single-pass transmembrane protein, is essential in the formation and maintenance of peripheral nervous system (PNS) compact myelin. P0 in Xenopus (xP0) exists primarily as a dimeric form that remains stable after various physical and chemical treatments. In exploring the nature of the interactions underlying the dimer stability, we found that xP0 dimer dissociated into monomer during continuous elution gel electrophoresis and conventional SDS-PAGE, indicating that the dimer is stabilized by non-covalent interactions. Furthermore, as some of the gel-purified monomer re-associated into dimer on SDS-PAGE gels, there is likely a dynamic equilibrium between xP0 dimer and monomer in vivo. Because the carbohydrate and fatty acyl moieties may be crucial for the adhesion role of P0, we used sensitive mass spectrometry approaches to elucidate the detailed N-glycosylation and S-acylation profiles of xP0. Asn92 was determined to be the single, fully-occupied glycosylation site of xP0, and a total of 12 glycans was detected that exhibited new structural features compared with those observed from P0 in other species: (1) the neutral glycans were composed mainly of high mannose and hybrid types; (2) five of twelve were acidic glycans, among which three were sialylated and the other two were sulfated; (3) none of the glycans had core fucosylation; and (4) no glucuronic acid, hence no HNK-1 epitope, was detected. The drastically different carbohydrate structures observed here support the concept of the species-specific variation in N-glycosylation of P0. Cys152 was found to be acylated with stearoyl (C18:0), whereas palmitoyl (C16:0) is the corresponding predominant fatty acyl group on P0 from higher vertebrates. We propose that the unique glycosylation and acylation patterns of Xenopus P0 may underlie its unusual dimerization behaviour. Our results should shed light on the understanding of the phylogenetic development of P0's adhesion role in PNS compact myelin.
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Affiliation(s)
- Bo Xie
- Mass Spectrometry Resource, Boston University School of Medicine, Boston, MA
| | | | - Cheng Zhao
- Mass Spectrometry Resource, Boston University School of Medicine, Boston, MA
| | | | - Shiu-Yung Chan
- Mass Spectrometry Resource, Boston University School of Medicine, Boston, MA
| | - Peter B. O’ Connor
- Mass Spectrometry Resource, Boston University School of Medicine, Boston, MA
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25
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Nelson AR, Borland L, Allbritton NL, Sims CE. Myristoyl-based transport of peptides into living cells. Biochemistry 2007; 46:14771-81. [PMID: 18044965 DOI: 10.1021/bi701295k] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Translocation of membrane-impermeant molecules to the interior of living cells is a necessity for many biochemical investigations. Myristoylation was studied as a means to introduce peptides into living cells. Uptake of a myristoylated, fluorescent peptide was efficient in the B lymphocyte cell line BA/F3. In contrast, this cell line was resistant to uptake of a cell-penetrating peptide derived from the TAT protein. In BA/F3 cells, membrane association was shown to be rapid, reaching a maximum within 30 min. Cellular uptake of the peptide lagged the membrane association but occurred within a similar time frame. Experiments performed at 37 versus 4 degrees C demonstrated profound temperature dependence in the cellular uptake of myristoylated cargo. Myristoylated peptides with either positive or negative charge were shown to load efficiently. In contrast to TAT-conjugated cargo, pyrenebutyrate did not enhance cellular uptake of the myristoylated peptide. The myristoylated peptide did not adversely affect cell viability at concentrations up to 100 muM. This assessment of myristoyl-based transport provides fundamental data needed in understanding the intracellular delivery of myristoylated peptide cargoes for cell-based biochemical studies.
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Affiliation(s)
- Allison R Nelson
- Department of Physiology and Biophysics, University of California, Irvine, California 92697, USA
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26
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Ribet D, Harper F, Dewannieux M, Pierron G, Heidmann T. Murine MusD retrotransposon: structure and molecular evolution of an "intracellularized" retrovirus. J Virol 2007; 81:1888-98. [PMID: 17151128 PMCID: PMC1797557 DOI: 10.1128/jvi.02051-06] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Accepted: 11/21/2006] [Indexed: 11/20/2022] Open
Abstract
We had previously identified active autonomous copies of the MusD long terminal repeat-retrotransposon family, which have retained transpositional activity. These elements are closely related to betaretroviruses but lack an envelope (env) gene. Here we show that these elements encode strictly intracellular virus-like particles that can unambiguously be identified by electron microscopy. We demonstrate intracellular maturation of the particles, with a significant proportion of densely packed cores for wild-type MusD but not for a protease mutant. We show that the molecular origin of this unexpected intracellular localization is solely dependent on the N-terminal part of the Gag protein, which lacks a functional sequence for myristoylation and plasma membrane targeting: replacement of the N-terminal domain of the MusD matrix protein by that of its closest relative-the Mason-Pfizer monkey virus-led to targeting of the MusD Gag to the plasma membrane, with viral particles budding and being released into the cell supernatant. These particles can further be pseudotyped with a heterologous envelope protein and become infectious, thus "reconstituting" a functional retrovirus prone to proviral insertions. Consistent with its retroviral origin, a sequence with a constitutive transport element-like activity can further be identified at the MusD 3' untranslated region. A molecular scenario is proposed that accounts for the transition, during evolution, from an ancestral infectious betaretrovirus to the strictly intracellular MusD retrotransposon, involving not only the loss of the env gene but also an inability to escape the cell--via altered targeting of the Gag protein--resulting de facto in the generation of a very successful "intracellularized" insertional mutagen.
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Affiliation(s)
- David Ribet
- Unité des Rétrovirus Endogènes et Eléments Rétroïdes des Eucaryotes Supérieurs, UMR 8122 CNRS, Institut Gustave Roussy, 39 Rue Camille Desmoulins, 94805 Villejuif Cedex, France
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27
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Burkala E, Poss M. Evolution of feline immunodeficiency virus Gag proteins. Virus Genes 2007; 35:251-64. [PMID: 17265140 DOI: 10.1007/s11262-006-0058-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Accepted: 11/13/2006] [Indexed: 01/23/2023]
Abstract
We evaluated the predicted biochemical properties of Gag proteins from a diverse group of feline immunodeficiency viruses (FIV) to determine how different evolutionary histories of virus and host have changed or constrained these important structural proteins. Our data are based on FIV sequences derived from domestic cat (FIVfca), cougar (FIVpco), and lions (FIVple). Analyses consisted of determining the selective forces acting at each position in the protein and the comparing predictions for secondary structure, charge, hydrophobicity and flexibility for matrix, capsid and nucleocapsid, and the C-terminal peptide, which comprise the Gag proteins. We demonstrate that differences among the FIV Gag proteins have largely arisen by neutral evolution, although many neutrally evolving regions have maintained biochemical features. Regions with predicted differences in biochemical features appear to involve intramolecular interactions and structural elements that undergo conformational changes during particle maturation. In contrast, the majority of sites involved in intermolecular contacts on the protein surface are constrained by purifying selection. There is also conservation of sites that interact with host proteins associated with cellular trafficking and particle budding. NC is the only protein with evidence of positive selection, two of which occur in the N-terminal region responsible for RNA binding and interaction with host proteins.
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Affiliation(s)
- Evan Burkala
- Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA
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28
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Kubo Y, Wada M, Ohba T, Takahashi N. Formation of retinoylated proteins from retinoyl-CoA in rat tissues. J Biochem 2006; 138:493-500. [PMID: 16272145 DOI: 10.1093/jb/mvi145] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Retinoylation (acylation of proteins by retinoic acid) is considered as one mechanism of retinoic acid (RA) action occurring in cells in vitro and in vivo. Previously, our studies showed that in rat tissues the formation of retinoyl-CoA from RA, the first step of retinoylation, required ATP, CoA and MgCl(2). In the current study, we examined whether the transfer of retinoyl-CoA into proteins, the second step of retinoylation, occurs in rat tissues. [(3)H]-Labeled-retinoyl-CoA bound covalently to proteins in rat liver, kidney, testis, and brain. The levels of incorporation of retinoyl-CoA into proteins were higher in vitamin A-deficient rats than in normal ones. The formation of retinoylated proteins depended on the incubation time, and the concentrations of retinoyl-CoA and homogenate. The reaction was suppressed by fatty acyl-CoAs and palmitic acid, but not by arachidonic acid. The Vmax and Km values for retinoyl-CoA in the formation of retinoylated proteins using a crude liver extract were estimated to be 2,597.3 pmol/min/mg protein and 9.5 x 10(-5) M, respectively. Retinoylated proteins formed from retinoyl-CoA, including a 17 kDa protein exhibiting high radioactivity, disappeared in the presence of 2-mercaptoethanol, indicating that RA was linked to the proteins through a thioester bond. These results demonstrate that retinoylation in rat tissues occurs via retinoyl-CoA formed from RA. This process may play a significant physiological role in cells.
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Affiliation(s)
- Yoshinori Kubo
- Laboratory of Physiological Chemistry, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501
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29
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Cione E, Tucci P, Senatore V, Ioele G, Genchi G. Binding of all-trans-retinoic acid to MLTC-1 proteins. Mol Cell Biochem 2006; 276:55-60. [PMID: 16132685 DOI: 10.1007/s11010-005-2845-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Accepted: 02/25/2005] [Indexed: 11/24/2022]
Abstract
The covalent incorporation of [(3)H]all-trans-retinoic acid into proteins has been studied in tumoural Leydig (MLTC-1) cells. The maximum retinoylation activity of MLTC-1 cell proteins was 710+/-29 mean+/-SD) fmoles/8 x 10(4) cells at 37 degrees C. About 90% of [(3)H]retinoic acid was trichloroacetic acid-soluble after proteinase-K digestion and about 65--75% after hydrolysis with hydroxylamine. Thus, retinoic acid is most probably linked to proteins as a thiol ester. The retinoylation reaction was inhibited by 13-cis-retinoic acid and 9-cis-retinoic acid with IC(50) values of 0.9 microM and 0.65 microM, respectively. Retinoylation was not inhibited by high concentrations of palmitic or myristic acids (250 microM); but there was an increase of the binding activity of about 25% and 130%, respectively. On the other hand, the retinoylation reaction was inhibited (about 40%) by 250 microM lauric acid. After pre-incubation of the cells with different concentrations of unlabeled RA, the retinoylation reaction with 100 nM [(3)H]RA involved first an increase at 100 nM RA and then a decrease of retinoylation activity between 200 and 600 nM RA. After cycloheximide treatment of the tumoural Leydig cells the binding activity of [(3)H]RA was about the same as that in the control, suggesting that the bond occurred on proteins in pre-existing cells.
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Affiliation(s)
- Erika Cione
- Dipartimento Farmaco-Biologico, Università della Calabria, Cosenza 87100, Italia
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Cione E, Tucci P, Chimento A, Pezzi V, Genchi G. Retinoylation reaction of proteins in Leydig (TM-3) cells. J Bioenerg Biomembr 2005; 37:43-8. [PMID: 15906148 DOI: 10.1007/s10863-005-4122-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2004] [Accepted: 12/01/2004] [Indexed: 11/28/2022]
Abstract
The covalent incorporation of [(3)H]all-trans-retinoic acid into proteins has been studied in Leydig (TM-3) cells. The maximum retinoylation activity of Leydig cells proteins was 570+/- 27 fmoles/8 x 10(4) cells at 37( composite function)C. About 95% of [(3)H]retinoic acid was trichloroacetic acid-soluble after proteinase-K digestion or after hydrolysis with hydroxylamine. Thus, retinoic acid is most probably linked to proteins as a thiol ester. The retinoylation process was inhibited by 13-cis-retinoic acid and 9-cis-retinoic acid with IC(50) values of 0.6 and 1.2 microM respectively. Dibutyryl-cAMP and forskolin increased the retinoylation activity by 75 and 81% at 500 and 25 microM respectively. Also hCG increased the retinoylation binding activity of 110% at 250 ng/mL. After cycloheximide treatment of the Leydig cells the binding activity of [(3)H]RA was about the same that in the control, suggesting that the bond occurs on proteins in pre-existing cells. Retinoylation was not inhibited by high concentrations of palmitic or myristic acids (500 microM); on the contrary, there was an increase of the binding activity of about 60 and 50% respectively.
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Affiliation(s)
- Erika Cione
- Dipartimento Farmaco-Biologico, Edificio Polifunzionale, Università della Calabria, 87036 Rende (Cosenza), Italy
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Cione E, Genchi G. Characterization of rat testes mitochondrial retinoylating system and its partial purification. J Bioenerg Biomembr 2004; 36:211-7. [PMID: 15224971 DOI: 10.1023/b:jobb.0000023625.22324.f0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Retinoylation (retinoic acid acylation), a posttranslational modification of proteins occurring in a variety of eukariotic cell lines both in vivo and in vitro, was studied in rat testes mitochondria. all-trans-Retinoic acid, a highly active form of vitamin A in inducing cellular differentiation, is incorporated covalently into proteins of rat testes mitochondria. The maximum retinoylation activity of rat testes mitochondrial proteins was 21.6 pmoles mg protein(-1) 90 min(-1) at 37 degrees C. The activation energy was 44 kJ mol(-1) from 5 to 37 degrees C. The retinoylation activity had a pH optimum of 7.5. The retinoylation process was specific for the presence of ATP, ADP, and GTP (even if only 30% of the control). The half saturation constant (Km) was 0.69 microM for all-trans-retinoic acid, while the inhibition constant (Ki) was 1.5 microM for 13-cis-retinoic acid. Retinoylation was not inhibited by high concentrations of myristic acid (MA) and palmitic acid (PA), indicating that retinoylation and acylation reactions involved different rat testes mitochondrial proteins. The ATP or CoASH saturation curves of retinoylation reaction showed sigmoidal behavior with apparent half saturation constants (K0.5) of 6.5 mM ATP and 40.6 microM CoASH. On SDS-gel electrophoresis, the hydroxylapaptite/celite eluate showed various protein bands between 25 and 80 kDa. This retinoylated protein was purified 17-fold with respect to the mitochondrial extract.
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Affiliation(s)
- Erika Cione
- Dipartimento Farmaco-Biologico, Edificio Polifunzionale, Università degli Studi della Calabria, Cosenza, Italy
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32
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Kim HJ, Yun CY, Cheon HM, Chae B, Lee IH, Park SJ, Kang YJ, Seo SJ. Hyphantria cunea ferritin heavy chain homologue: cDNA sequence and mRNA expression. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2004; 56:21-33. [PMID: 15101063 DOI: 10.1002/arch.10141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We have sequenced a cDNA clone encoding a 26-kDa ferritin subunit, which was heavy chain homologue (HCH), in fall webworm, Hyphantria cunea. The HCH cDNA was obtained from the screening of a cDNA library using a PCR product. H. cunea ferritin is composed of 221 amino acid residues and their calculated mass is 26,160 Da. The protein contains the conserved motifs for the ferroxidase center typical for heavy chains of vertebrate ferritin. The iron-responsive element sequence with a predicted stem-loop structure is present in the 5'-untranslated region of ferritin HCH mRNA. The sequence alignment of ferritin HCH shows 68.9 and 68.7% identity with Galleria mellonella HCH (26 kDa ferritin) and Manduca sexta HCH, respectively. While G type insect ferritin vertebrate light chain homologue (LCH) is distantly related to H. cunea ferritin HCH (17.2-20.8%), the Northern blot analysis revealed that H. cunea ferritin HCH was ubiquitously expressed in various tissues and all developmental stages. The ferritin expression of midgut is more responsive to iron-fed, compared to fat body in H. cunea.
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Affiliation(s)
- Hong Ja Kim
- Division of Life Science, Gyeongsang National University, Jinju, Korea
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Giuntini J, Giusti L, Lucacchini A, Mazzoni MR. Modulation of A1 adenosine receptor signaling by peroxynitrite. Biochem Pharmacol 2004; 67:375-83. [PMID: 14698049 DOI: 10.1016/j.bcp.2003.08.045] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Nitric oxide (NO) is a gaseous free radical involved in many pathophysiological processes. During oxidative stress, NO, its derivatives and adenosine are released. Considering adenosine neuroprotective role in the central nervous system (CNS) and toxicity of NO, we investigated the effect of a NO/peroxynitrite (ONOO(-)) donor, 3-morpholinosydnonimine (SIN-1), on A(1) adenosine receptor (A(1)AR) signaling pathway in rat cortical membranes. Membrane treatment with 0.5mM SIN-1 for various periods of time (0-240min) decreased specific binding of the radiolabeled A(1)AR agonist, [3H]N(6)-cyclohexyladenosine ([3H]CHA), in a time-dependent manner, reaching the steady state after 120min. The inhibitory effect of SIN-1 was concentration-dependent, with an EC(50) value of 0.60+/-0.30mM (N=3). Membrane pre-incubation with the superoxide anion (O(2)z.rad;(-)) scavenger superoxide dismutase (SOD) followed by SIN-1 addition, abolished SIN-1 inhibition of [3H]CHA binding. Membrane treatment with 0.5mM SIN-1 for 120min caused a significant 2-fold increase of the K(D) value for [3H]CHA without changing the B(max) value. Moreover, pre-incubation of membranes with A(1)AR agonists, CHA or N(6)-(2-phenylisopropyl)-adenosine (R-PIA) before SIN-1 addition increased the inhibitory effect while the selective A(1)AR antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) had no activity. Membrane treatment with SIN-1 decreased receptor-stimulated guanosine 5'-O-(gamma[35S]thio)triphosphate ([35S]GTPgammaS) binding in a concentration-dependent manner. This treatment influenced [35S]GTPgammaS binding affinity for A(1)AR activated G(i) proteins in cortical membranes. These findings suggest that ONOO(-) modulates A(1)AR signaling pathways by affecting receptor G(i) protein coupling.
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Affiliation(s)
- Janette Giuntini
- Dipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie, Università di Pisa, Pisa, Italy
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Hanakam F, Gerisch G. Monitoring intracellular shutting of histidine-rich pH sensor proteins tagged with green fluorescent protein. Methods Enzymol 2003; 302:51-8. [PMID: 12876762 DOI: 10.1016/s0076-6879(99)02009-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Affiliation(s)
- F Hanakam
- Micromet GmbH, D-82152 Martinsried, Germany
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Heath CM, Windsor M, Wileman T. Membrane association facilitates the correct processing of pp220 during production of the major matrix proteins of African swine fever virus. J Virol 2003; 77:1682-90. [PMID: 12525602 PMCID: PMC140870 DOI: 10.1128/jvi.77.3.1682-1690.2003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The African swine fever (ASF) virus polyprotein pp220 is processed at Gly-Gly-X sites by a virally encoded SUMO-like protease to produce matrix proteins p150, p37, p34, and p14. Four Gly-Gly-X sites are used to produce the matrix proteins, but the polyprotein contains an additional 15 sites potentially recognized by the protease. This study shows that cleavage occurs at many, if not all, Gly-Gly-X sites, and at steady state, p150 and p34 are minor products of processing. Significantly, only the final structural proteins, p150 and p34, were found in mature virions, suggesting that there is a mechanism for excluding incorrectly processed forms. ASF virus is assembled on the cytoplasmic face of the endoplasmic reticulum, and the distribution of pp220 products between membranes and cytosol was studied. Incorrectly processed forms of p34 were recovered from both the cytosol and membrane fractions. Interestingly, p34 was only detected in the membrane fraction, and of the many processed forms bound to membranes, only p34 was protected from trypsin, suggesting envelopment. The majority of the incorrectly processed forms of p150 were recovered from the cytosol. Again, the correct product of processing, p150, was selectively recruited to membranes. Sucrose density centrifugation showed that membrane-associated forms of p34 and p150 assembled into large structures suggestive of a viral matrix, while cytosolic and/or incorrectly processed forms of pp220 did not. Taken together, these results suggest that association with cellular membranes is important for regulating the correct processing of pp220 and the packaging of matrix proteins into virions.
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Affiliation(s)
- Colin M Heath
- Institute for Animal Health, Pirbright Laboratories, Woking, Surrey GU24 0NF, United Kingdom
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36
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Abstract
Cell differentiation is essential for normal growth and homeostasis, and drug-induced differentiation of tumor cells into benign or normal cells is an important approach for anticancer chemotherapy. Studies of induction mechanisms for cell differentiation and discovery of differentiation-inducing factors are thus critical components of drug development. The Screening of differentiation-inducing factors, such as purified aldehyde reductase, a xenobiotic metabolite enzyme, that induces differentiation of human acute myeloid leukemia HL60 cells into monocyte/macrophage cells is described. Mechanisms of all-trans-retinoic acid (RA)-induced differentiation are also covered. RA is a potent inducer of HL60 cell differentiation and when used as a sole agent it can induce complete remission in patients with acute promyelocytic leukemia (APL). While one mechanism of the effect of RA involves RA nuclear receptors, retinoylation (a posttranslational modification of proteins by RA) may be a new nongenomic mechanism by which RA acts on cells. An early event in RA-induced differentiation may be retinoylation of RII alpha (regulatory subunits of cAMP-dependent protein kinase), in which RII alpha units are retinoylated and the retinoylated RII alpha is then translocated to the nucleus. Drugs can also be combined with RA in RA-differentiation therapy. Cytodifferation therapy by RA in APL patients exhibits limitations due to the resistance of relapsed patients to further RA treatment. This may occur through the induction of expression of various genes that reduce RA blood concentrations. Treatment with combinations of RA and other agents may be one way to reduce induction of those genes. Good candidates for such agents include cAMP-elevating agents, retinoids, steroids, and fatty acids that synergistically induce differentiation of HL60 cells. Two derivatives of falconensone A, falconensone A p-bromophenylhydrazone, which has a bromophenyl residue, and falconensone A dioxime, which possesses a hydroxy residue, were synthesized to incorporate features of RA and N-[4-hydroxyphenyl] retinamide. Both derivatives have exhibited more potent biological activity than the parent falconensone A in vitro and in vivo.
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Affiliation(s)
- Noriko Takahashi
- Department of Health Chemistry, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
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37
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Hatanaka H, Iourin O, Rao Z, Fry E, Kingsman A, Stuart DI. Structure of equine infectious anemia virus matrix protein. J Virol 2002; 76:1876-83. [PMID: 11799182 PMCID: PMC135893 DOI: 10.1128/jvi.76.4.1876-1883.2002] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Gag polyprotein is key to the budding of retroviruses from host cells and is cleaved upon virion maturation, the N-terminal membrane-binding domain forming the matrix protein (MA). The 2.8-A resolution crystal structure of MA of equine infectious anemia virus (EIAV), a lentivirus, reveals that, despite showing no sequence similarity, more than half of the molecule can be superimposed on the MAs of human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV). However, unlike the structures formed by HIV-1 and SIV MAs, the oligomerization state observed is not trimeric. We discuss the potential of this molecule for membrane binding in the light of conformational differences between EIAV MA and HIV or SIV MA.
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Affiliation(s)
- Hideki Hatanaka
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom
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38
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Haziza B, Chauvin JP, Gluschankof P, Suzan M. Caprine arthritis encephalitis virus: evidence for a B/D-type assembly pathway in a C-type lentivirus replication. Virology 2001; 286:434-45. [PMID: 11485411 DOI: 10.1006/viro.2001.1000] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lentiviruses, among which is caprine arthritis encephalitis virus (CAEV), are known to concomitantly assemble and bud at the plasma membrane of infected cells, in a C-type defined pathway. Electron microscopy analysis of CAEV-infected cells demonstrated viral particles budding at the plasma membrane and into intracellular membrane-surrounded vesicles. Furthermore, nonenveloped immature virus-like particles, resembling intracytoplasmic type-A particles (ICAPs), accumulated within the cytoplasm of those cells. Fractionation on sucrose density gradients of cytoplasmic lysates from CAEV-infected cells revealed that enveloped immature or mature viral particles had a density of 1.16--1.17 g/ml, whereas ICAPs sedimented at a density of 1.2--1.27 g/ml. Endogenous reverse transcriptase activity was only associated with the 1.16--1.17 g/ml density particles despite the presence of viral RNA in both populations. The intracellular enveloped particles were found to be infectious. The CAEV Gag precursor by itself was shown to direct assembly, budding, and release of immature virus-like particles when expressed in goat primary synovial membrane cells using the same pathways of assembly and budding as observed in CAEV-infected cells. These data suggest that CAEV assembly, driven by the Gag precursor, could unusually proceed via two simultaneous pathways characteristic of type-C and type-B/D retroviruses.
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Affiliation(s)
- B Haziza
- Inserm U372, 13178 Marseille cedex 09, France
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39
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Abstract
The first 86 residues of the Rous sarcoma virus (RSV) Gag protein form a membrane-binding (M) domain that directs Gag to the plasma membrane during budding. Unlike other retroviral Gag proteins, RSV Gag is not myristylated; however, the RSV M domain does contain 11 basic residues that could potentially interact with acidic phospholipids in the plasma membrane. To investigate this possibility, we analyzed mutants in which basic residues in the M domain were replaced with asparagines or glutamines. The data show that neutralizing as few as two basic residues in the M domain blocked particle release and prevented Gag from localizing to the plasma membrane. Though not as severe, single neutralizations also diminished budding and, when expressed in the context of proviral clones, reduced the ability of RSV to spread in cell cultures. To further explore the role of basic residues in particle production, we added lysines to new positions in the M domain. Using this approach, we found that the budding efficiency of RSV Gag can be improved by adding pairs of lysines and that the basic residues in the M domain can be repositioned without affecting particle release. These data provide the first gain-of-function evidence for the importance of basic residues in a retroviral M domain and support a model in which RSV Gag binds to the plasma membrane via electrostatic interactions.
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Affiliation(s)
- E M Callahan
- Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA
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40
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Abstract
BACKGROUND Dynamic protein palmitoylation of signalling proteins is thought to be an important step in the regulation of signal transduction in eukaryotic cells. The enzyme responsible for protein palmitoylation in vertebrates, however, has not been identified. I have previously reported that p260/270, which is expressed in embryos of the silkworm Bombyx mori, has protein palmitoylase activity. RESULTS A homologue of Bombyx p260/270, mouse fatty-acid synthase (FAS), was shown to be expressed specifically throughout most of the central and peripheral nervous system in mouse embryos. Mouse FAS was expressed specifically in cultured primary neurones in which growth-associated protein (GAP)-43 was expressed. GAP-43, by protein palmitoylation, regulates Go signal transduction and neural axonal growth. In a cell-free system, purified FAS from mouse embryos transferred palmitate to GAP-43 through cysteine residues. Furthermore, cerulenin, an inhibitor of FAS, reduced axonal growth and in vivo palmitoylation of GAP-43 in cultured neurones. CONCLUSIONS Mouse FAS was hypothesized to be responsible for the palmitoylation of GAP-43 and subsequent regulation of axonal growth in mouse embryos.
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Affiliation(s)
- K Ueno
- Department of Developmental Biology, National Institute for Basic Biology, Myodaiji, Okazaki 444-8585, Japan.
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41
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Cohen I, Girard J, Prip-Buus C. Biogenesis of the rat liver mitochondrial carnitine palmitoyltransferase I. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 466:1-16. [PMID: 10709623 DOI: 10.1007/0-306-46818-2_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Affiliation(s)
- I Cohen
- Endocrinologie, Métabolisme et Développement CNRS UPR1524, Meudon, France
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42
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Smialowski-Fléter S, Moulin A, Villard C, Puigserver A. Structure-function relationships in the carboxylic-ester-hydrolase superfamily. Disulfide bridge arrangement in porcine intestinal glycerol-ester hydrolase. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:2227-34. [PMID: 10759845 DOI: 10.1046/j.1432-1327.2000.01224.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
CNBr fragments from porcine intestinal glycerol-ester hydrolase were separated by SDS/PAGE under reducing and nonreducing conditions, and their amino-acid sequences were analysed. Two intra-chain disulfide bridges were identified, namely Cys70-Cys99 (loop A) and Cys256-Cys267 (loop B). As the Cys71 sulfhydryl group could not be alkylated with iodoacetamide, it is suggested that the residue is blocked rather than being present in the free form. The two disulfide bridges of intestinal glycerol-ester hydrolase are present in the cholinesterase family, although the enzyme showed only about 35% identity with these proteins. Furthermore, the finding that glycerol-ester hydrolase was partly inactivated under reducing conditions suggests that one or both disulfide bridges are important for the enzyme conformation. Lastly, glycerol-ester hydrolase was also found to hydrolyse cholinergic substrates, although residues Trp86 and Asp74 which are considered to be the main constituents of the 'anionic' subsite responsible for substrate binding in cholinesterases were absent from loop A. Other amino-acid residues in the glycerol-ester hydrolase may therefore be responsible for the binding of cholinergic substrates to the enzyme.
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Affiliation(s)
- S Smialowski-Fléter
- Laboratoire de Biochimie et Biologie de la Nutrition, Faculté des Sciences et Techniques de St-Jérôme, Marseille, France
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43
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Faergeman NJ, Ballegaard T, Knudsen J, Black PN, DiRusso C. Possible roles of long-chain fatty Acyl-CoA esters in the fusion of biomembranes. Subcell Biochem 2000; 34:175-231. [PMID: 10808334 DOI: 10.1007/0-306-46824-7_5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Affiliation(s)
- N J Faergeman
- Department of Biochemistry and Molecular Biology, Albany Medical College, New York 12208, USA
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44
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Nichol H, Locke M. Secreted ferritin subunits are of two kinds in insects molecular cloning of cDNAs encoding two major subunits of secreted ferritin from Calpodes ethlius. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 1999; 29:999-1013. [PMID: 10560139 DOI: 10.1016/s0965-1748(99)00076-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In insects, holoferritin is easily visible in the vacuolar system of tissues that filter the hemolymph and, at least in Lepidoptera, is abundant in the hemolymph. Sequences reported for insect secreted ferritins from Lepidoptera and Diptera have high sequence diversity. We examined the nature of this diversity for the first time by analyzing sequences of cDNAs encoding two ferritin subunits from one species, Calpodes ethlius (Lepidoptera, Hesperiidae). We found that insect secreted ferritin subunits are of two types with little resemblance to each other. Ferritin was isolated from iron loaded hemolymph of C. ethlius fifth instar larvae by differential centrifugation. The N-terminal amino acid sequences for the nonglycosylated subunit with Mr 24,000 (S) and the largest glycosylated subunit with Mr 31,000 (G) were determined. The N-termini of the two subunits were different and were used to construct degenerate PCR primers. The same cDNA products were amplified from cDNA libraries from the midgut which secretes holoferritin and from the fat body which secretes iron-poor apoferritin. The G subunit most closely resembles the glycosylated ferritin subunit from Manduca sexta and the S subunit resembles the Drosophila small subunit. The S and G subunits from Calpodes were dissimilar and distinct from the cytosolic ferritins of vertebrates and invertebrates. Additional sequences were obtained by 5' and 3' RACE from separate fat body and midgut RACE libraries. cDNAs encoding both subunits had a consensus iron responsive element (IRE) in a conserved cap-distal location of their 5' UTR. An integrin-binding RGD motif found in the G subunit and conserved in Manduca may facilitate iron uptake through a calreticulin (mobilferrin)/integrin pathway. Calpodes and other insect ferritins have conserved cysteine residues to which fatty acids can be linked. Dynamic acylation of ferritin may slow but not prevent its passage out of the ER.
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Affiliation(s)
- H Nichol
- Department of Zoology, University of Western Ontario, London, Canada
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45
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Little EB, Edelman GM, Cunningham BA. Palmitoylation of the cytoplasmic domain of the neural cell adhesion molecule N-CAM serves as an anchor to cellular membranes. CELL ADHESION AND COMMUNICATION 1999; 6:415-30. [PMID: 10223357 DOI: 10.3109/15419069809109150] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The neural cell adhesion molecule N-CAM is expressed at key sites during embryonic development and mediates homophilic adhesion between cells both in the embryo and in the adult. N-CAM is expressed in multiple forms and two of the major isoforms differ in their cytoplasmic domains, one (ld form) having an insert of 261 amino acids that is missing in the other (sd form). N-CAM has been previously shown to be palmitoylated, but the sites of acylation have not been localized. We show here that the cytoplasmic domain of the N-CAM became palmitoylated after transfection of a cDNA encoding N-CAM into COS-7 cells, and that this acylation occurs on the four closely spaced cysteines in the cytoplasmic domain of N-CAM. Moreover, when a cDNA encoding only the cytoplasmic domain was transfected into cells, the protein was palmitoylated and associated with membranes even though it lacked a membrane spanning segment. Site directed mutagenesis of the four cysteine residues to serines at positions 5, 11, 16, and 22 in the cytoplasmic domain (723, 729, 734, and 740 in the native protein) eliminated both the palmitoylation and association with the membrane fraction. Mutagenesis of the cysteines individually, in pairs, and in groups of three indicated that C5 is not acylated with either palmitate or oleate, but the other three cysteines are acylated to different extents. Cytoplasmic domains with single cysteine mutations localized primarily in the membrane fraction, while those with three mutations were found primarily in the cytoplasm. Proteins containing two mutated cysteines were found in both the cytoplasm and the membrane fraction with C11 and C16 having the most influence on the distribution in accord with their higher level of acylation. Mutation of the cysteines did not affect the ability of full-length N-CAM to promote aggregation when transfected into COS-7 cells. Based on these results we suggest that the primary role of palmitoylation is to provide a second anchor in the plasma membrane to direct the protein to discrete membrane microdomains or to organize the cytoplasmic region for interaction with factors that affect signaling events resulting from N-CAM mediated adhesion.
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Affiliation(s)
- E B Little
- Department of Neurobiology, The Scripps Research Institute, La Jolla, CA 92037, USA
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46
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Lee YM, Tian CJ, Yu XF. A bipartite membrane-binding signal in the human immunodeficiency virus type 1 matrix protein is required for the proteolytic processing of Gag precursors in a cell type-dependent manner. J Virol 1998; 72:9061-8. [PMID: 9765451 PMCID: PMC110323 DOI: 10.1128/jvi.72.11.9061-9068.1998] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
It is unclear whether proteolytic processing of the human immunodeficiency virus type 1 (HIV-1) Gag protein is dependent on virus assembly at the plasma membrane. Mutations that prevent myristylation of HIV-1 Gag proteins have been shown to block virus assembly and release from the plasma membrane of COS cells but do not prevent processing of Gag proteins. In contrast, in HeLa cells similar mutations abolished processing of Gag proteins as well as virus production. We have now addressed this issue with CD4(+) T cells, which are natural target cells of HIV-1. In these cells, myristylation of Gag proteins was required for proteolytic processing of Gag proteins and production of extracellular viral particles. This result was not due to a lack of expression of the viral protease in the form of a Gag-Pol precursor or a lack of interaction between unmyristylated Gag and Gag-Pol precursors. The processing defect of unmyristylated Gag was partially rescued ex vivo by coexpression with wild-type myristylated Gag proteins in HeLa cells. The cell type-dependent processing of HIV-1 Gag precursors was also observed when another part of the plasma membrane binding signal, a polybasic region in the matrix protein, was mutated. The processing of unmyristylated Gag precursors was inhibited in COS cells by HIV-1 protease inhibitors. Altogether, our findings demonstrate that the processing of HIV-1 Gag precursors in CD4(+) T cells occurs normally at the plasma membrane during viral morphogenesis. The intracellular environment of COS cells presumably allows activation of the viral protease and proteolytic processing of HIV-1 Gag proteins in the absence of plasma membrane binding.
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Affiliation(s)
- Y M Lee
- Department of Molecular Microbiology and Immunology, Johns Hopkins University School of Hygiene and Public Health, Baltimore, Maryland 21205, USA
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47
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Gehring L, Haase D, Habben K, Kerkhoff C, Meyer HH, Kaever V. Synthesis of an unsaturated fatty acid analogue (18-(4′-azido-2′-hydroxybenzoylamino)-oleic acid) and its interaction with lysophosphatidylcholine: acyl-CoA-O-acyltransferase. J Lipid Res 1998. [DOI: 10.1016/s0022-2275(20)33882-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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48
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Kiernan RE, Ono A, Englund G, Freed EO. Role of matrix in an early postentry step in the human immunodeficiency virus type 1 life cycle. J Virol 1998; 72:4116-26. [PMID: 9557701 PMCID: PMC109641 DOI: 10.1128/jvi.72.5.4116-4126.1998] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The matrix protein of human immunodeficiency virus type 1 (HIV-1) has been reported to play a crucial role in the targeting of the Gag polyprotein precursor to the plasma membrane and in the incorporation of viral envelope glycoproteins into budding virions. In this report, we present evidence that mutation of a highly conserved Leu at matrix amino acid 20 blocks or markedly delays virus replication in a range of cell types, including T-cell lines, primary human peripheral blood mononuclear cells, and monocyte-derived macrophages. These mutations do not impair virus assembly and release, RNA encapsidation, or envelope glycoprotein incorporation into virions but rather cause significant defects in an early step in the virus life cycle, as measured by single-cycle infectivity assays and the analysis of viral DNA synthesis early postinfection. This infectivity defect is independent of the type of envelope glycoprotein carried on mutant virions; similar results are obtained in pseudotyping experiments using wild-type or truncated HIV-1 envelope glycoproteins, the amphotropic murine leukemia virus envelope, or the vesicular stomatitis G protein. Intriguingly, matrix residue 20 mutations also increase the apparent binding of Gag to membrane, accelerate the kinetics of Gag processing, and induce defects in endogenous reverse transcriptase activity without affecting virion density or morphology. These results help elucidate the function of matrix in HIV-1 replication.
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Affiliation(s)
- R E Kiernan
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0460, USA
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49
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Weldon RA, Parker WB, Sakalian M, Hunter E. Type D retrovirus capsid assembly and release are active events requiring ATP. J Virol 1998; 72:3098-106. [PMID: 9525635 PMCID: PMC109760 DOI: 10.1128/jvi.72.4.3098-3106.1998] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Mason-Pfizer monkey virus (M-PMV), the prototype type D retrovirus, differs from most other retroviruses by assembling its Gag polyproteins into procapsids in the cytoplasm of infected cells. Once assembled, the procapsids migrate to the plasma membrane, where they acquire their envelope during budding. Because the processes of M-PMV protein transport, procapsid assembly, and budding are temporally and spatially unlinked, we have been able to determine whether cellular proteins play an active role during the different stages of procapsid morphogenesis. We report here that at least two stages of morphogenesis require ATP. Both procapsid assembly and procapsid transport to the plasma membrane were reversibly blocked by treating infected cells with sodium azide and 2-deoxy-D-glucose, which we show rapidly and reversibly depletes cellular ATP pools. Assembly of procapsids in vitro in a cell-free translation/assembly system was inhibited by the addition of nonhydrolyzable ATP analogs, suggesting that ATP hydrolysis and not just ATP binding is required. Since retrovirus Gag polyproteins do not bind or hydrolyze ATP, these results demonstrate that cellular components must play an active role during retrovirus morphogenesis.
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Affiliation(s)
- R A Weldon
- Department of Microbiology, University of Alabama at Birmingham, 35294, USA
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50
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Abstract
The matrix (MA) protein of human immunodeficiency virus type 1 (HIV-1) plays a critical role in virion morphogenesis and fulfills important functions during the early steps of infection. In an effort to identify cellular partners of MA, a Saccharomyces cerevisiae two-hybrid screen was utilized. A specific interaction between MA and HO3, a putative histidyl-tRNA synthetase, was demonstrated in this system. HO3-specific mRNA was detected in several tissues relevant for HIV infection, such as spleen, thymus, and peripheral blood lymphocytes, as well as in a number of T-lymphoid-cell lines. The binding of MA to HO3 was confirmed in transfected cells by coimmunoprecipitation. This interaction was abrogated by replacing two lysine residues at positions 26 and 27 of MA by threonine (MA(KK27TT)). HO3 localized both to the cytoplasm and to the nucleus of acutely transfected 293T cells. When overexpressed in HIV-1-producing cells, HO3 was incorporated into wild-type virions but not in ones containing the dilysine-mutated variant of MA. Correspondingly, overexpression of HO3 in virus producer cells enhanced the infectivity of wild-type but not MA(KK27AA) HIV-1 particles. The stimulating effect of HO3 was independent from the presence of Envelope, Vpr, or Vpu. Taken together, these results suggest that HO3, through its recognition of MA, plays a role in the life cycle of HIV-1.
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Affiliation(s)
- J Lama
- Infectious Disease Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
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