A novel nuclear export activity in HIV-1 matrix protein required for viral replication

Dupont, Stefan A.; Шарова, Н. П.; DeHoratius, C; Virbasius, Ching-Man A.; Zhu, Xiaochun; Bukrinskaya, A. G.; Stevenson, Mario; Green, Michael R.

doi:10.1038/45272

Cited by 114 publications

(101 citation statements)

References 23 publications

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“…The HIV-1 MA domain was reported previously to have two NLSs (5,21) and one NES (13), but multiple subsequent reports have shown that HIV-1 MA-GFP is excluded from the nucleus (2,10) and that it does not contain a conventional NLS (15,22). Two studies in the past year confirmed that HIV-1 Gag lacks a CRM1-dependent nuclear export signal (2,18).…”

Section: Discussionmentioning

confidence: 96%

Feline Immunodeficiency Virus Gag Is a Nuclear Shuttling Protein

Kemler

Saenz

Poeschla

2012

J Virol

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Lentiviral genomic RNAs are encapsidated by the viral Gag protein during virion assembly. The intracellular location of the initial Gag-RNA interaction is unknown. We previously observed feline immunodeficiency virus (FIV) Gag accumulating at the nuclear envelope during live-cell imaging, which suggested that trafficking of human immunodeficiency virus type 1 (HIV-1) and FIV Gag may differ. Here we analyzed the nucleocytoplasmic transport properties of both Gag proteins. We discovered that inhibition of the CRM1 nuclear export pathway with leptomycin B causes FIV Gag but not HIV-1 Gag to accumulate in the nucleus. Virtually all FIV Gag rapidly became intranuclear when the CRM1 export pathway was blocked, implying that most if not all FIV Gag normally undergoes nuclear cycling. In FIV-infected feline cells, some intranuclear Gag was detected in the steady state without leptomycin B treatment. When expressed individually, the FIV matrix (MA), capsid (CA), and nucleocapsid-p2 (NC-p2) domains were not capable of mediating leptomycin B-sensitive nuclear export of a fluorescent protein. In contrast, CA-NC-p2 did mediate nuclear export, with MA being dispensable. We conclude that HIV-1 and FIV Gag differ strikingly in a key intracellular trafficking property. FIV Gag is a nuclear shuttling protein that utilizes the CRM1 nuclear export pathway, while HIV-1 Gag is excluded from the nucleus. These findings expand the spectrum of lentiviral Gag behaviors and raise the possibility that FIV genome encapsidation may initiate in the nucleus.G ag is both necessary and sufficient for retrovirus particle formation and budding. The protein is translated on free polysomes and targeted to the plasma membrane, where virus particles are assembled (16). A central question is whether Gag and the viral genomic RNA (gRNA) associate at the plasma membrane or earlier during assembly and, if so, whether this occurs in the cytosol; in association with organelles, e.g., cotranslationally; or even in the nucleus, as was described previously for an alpharetrovirus (17). Human immunodeficiency virus type 1 (HIV-1) gRNAs become anchored at the plasma membrane before particle assembly is detectable, but it is not clear whether the Gag-gRNA complexes of this and other lentiviruses first form in the cytoplasm and then transit to the plasma membrane or the gRNA traffics there independently (26,27). Biochemical experiments supported the former scenario, with a monomer or low-order multimers forming on HIV-1 gRNAs and higher-order multimer formation depending on subsequent plasma membrane interactions (33).Gag is encoded by the full-length unspliced viral RNA. To circumvent the cellular checkpoint that prevents the export of intron-containing mRNA, lentiviruses express Rev, which functions as an adaptor between the cellular karyopherin CRM1/exportin-1 and a Rev response element (RRE) located in the 3= region of unspliced viral RNAs (9). However, the main cellular function of the CRM1 nuclear export pathway is the export of cellular proteins containing a...

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Section: Discussionmentioning

confidence: 96%

Feline Immunodeficiency Virus Gag Is a Nuclear Shuttling Protein

Kemler

Saenz

Poeschla

2012

J Virol

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“…Viruses provide excellent paradigms of proteins that play structural and functional roles, a strategy to overcome the reduced size of their genomes compared with the numerous functions required for infectivity. Capsid proteins of viruses, besides serving as building blocks can also participate in genome replication (Dupont et al, 1999), transcription (Rosa-Calatrava et al, 2001), translation, encapsidation (Tahara et al, 1998) or support systemic movement of viral nucleic acid (Schneider et al, 1997). In the case of bacterial viruses and herpes viruses, an instructive example of a structural protein that plays key non-structural roles is the portal protein (reviewed by Valpuesta and Carrascosa, 1994;Newcomb et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

The high‐resolution functional map of bacteriophage SPP1 portal protein

Isidro

Santos

Henriques

et al. 2003

Molecular Microbiology

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SummaryAn essential component in the assembly of nucleocapsids of tailed bacteriophages and of herpes viruses is the portal protein that is located at the unique vertex of the icosahedral capsid through which DNA movements occur. A library of mutations in the bacteriophage SPP1 portal protein (gp6) was generated by random mutagenesis of gene 6 . Screening of the library allowed identification of 67 single amino acid substitutions that impair portal protein function. Most of the mutations cluster within stretches of a few amino acids in the gp6 carboxyl-terminus. The mutations were divided into five classes according to the step of virus assembly that they impair: (1) production of stable gp6; (2) interaction of gp6 with the minor capsid protein gp7; (3) incorporation of gp6 in the procapsid structure; (4) DNA packaging; and (5) sizing of the packaged DNA molecule. Most of the mutations fell in classes 3 and 4. This is the first high-resolution functional map of a portal protein, in which its function at different steps of viral assembly can be directly correlated with specific regions of its sequence. The work provides a framework for the understanding of central processes in the assembly of viruses that use specialized portals to govern entry and exit of DNA from the viral capsid.

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“…Prior to the suggestion of this nucleotide-level, cis-acting mechanism, peptide signals in HIV-1 MA [127][128][129][130][131][132][133][134][135], IN [132,136] and Vpr [100,130,[137][138][139][140] were implicated in signal-mediated transport of the preintegration complex through the nuclear pore (reviewed in [98,99,101,141]). Some functional assignments to proteins have also been contested [142][143][144][145] and the whole area of the mechanism of nuclear import is regarded as unsettled at present; for current summaries of these controversies, see [99,102].…”

Section: Mechanisms Of Lentiviral Nuclear Import: Central Dna Flaps Amentioning

confidence: 99%

FIV: from lentivirus to lentivector

Saenz

Poeschla

2004

J. Gene Med.

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SummaryMolecular virological understanding of the feline immunodeficiency virus (FIV) life cycle is increasing, facilitating rational derivation of improved vectors from this non-primate lentivirus. The packaging signal has been mapped, a central DNA flap has been identified, and class I integrase mutants have been validated. Vector systems with improved effectiveness and safety profiles are being applied by a number of laboratories in several pre-clinical models, with demonstrated efficacy in human tissues. The comparative lentivirological research that facilitates FIV vector development may also yield insights into the still enigmatic molecular basis for a signature lentiviral property with pathogenetic and therapeutic importance: permanent transgene integration in non-dividing cells. This review discusses virological aspects of lentiviral vector development, as well as some recent controversies and applications.

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A novel nuclear export activity in HIV-1 matrix protein required for viral replication

Cited by 114 publications

References 23 publications

Feline Immunodeficiency Virus Gag Is a Nuclear Shuttling Protein

Feline Immunodeficiency Virus Gag Is a Nuclear Shuttling Protein

The high‐resolution functional map of bacteriophage SPP1 portal protein

FIV: from lentivirus to lentivector

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