CPSF6 Defines a Conserved Capsid Interface that Modulates HIV-1 Replication

Price, Amanda J.; Fletcher, Adam J.; Schaller, Torsten; Elliott, Tom; Lee, Kyeongeun; KewalRamani, Vineet N.; Chin, Jason W.; Towers, Greg J.; James, Leo C.

doi:10.1371/journal.ppat.1002896

Cited by 239 publications

(388 citation statements)

References 44 publications

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“…5), arguing that HIV-1 replication does not rely on the steadystate level of Tnpo3-CPSF6 complexes. These results agree with the model whereby cytoplasmically delocalized CPSF6 inhibits HIV-1 infectivity via premature engagement of the viral capsid (31,35). The antagonistic HIV-1 capsid-CPSF6 interaction is supported by a substantial weight of genetic evidence, and potential nuclear functions of CPSF6 as an HIV-1 host factor remain an intriguing possibility for further investigation (30-32, 34, 49, 50).…”

Section: Resultssupporting

confidence: 85%

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Structural basis for nuclear import of splicing factors by human Transportin 3

Maertens

Cook

Wang

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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130

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Transportin 3 (Tnpo3, Transportin-SR2) is implicated in nuclear import of splicing factors and HIV-1 replication. Herein, we show that the majority of cellular Tnpo3 binding partners contain arginineserine (RS) repeat domains and present crystal structures of human Tnpo3 in its free as well as GTPase Ran-and alternative splicing factor/splicing factor 2 (ASF/SF2)-bound forms. The flexible β-karyopherin fold of Tnpo3 embraces the RNA recognition motif and RS domains of the cargo. A constellation of charged residues on and around the arginine-rich helix of Tnpo3 HEAT repeat 15 engage the phosphorylated RS domain and are critical for the recognition and nuclear import of ASF/SF2. Mutations in the same region of Tnpo3 impair its interaction with the cleavage and polyadenylation specificity factor 6 (CPSF6) and its ability to support HIV-1 replication. Steric incompatibility of the RS domain and RanGTP engagement by Tnpo3 provides the mechanism for cargo release in the nucleus. Our results elucidate the structural bases for nuclear import of splicing factors and the Tnpo3-CPSF6 nexus in HIV-1 biology.T he transport of macromolecules between cytoplasm and nucleus is orchestrated by a family of nuclear import and export receptors (1). Referred to as importins and exportins, these proteins bind their specific cargoes and translocate them across the nuclear pore complex. The process is regulated by the small GTPase Ran that partitions between cytoplasm and nucleus in the predominantly GDP-and GTP-bound form, respectively. Importins associate with their cargoes in the cytoplasm, and the competitive binding of RanGTP induces them to release their cargoes in the nucleus (2). Most nuclear import/export receptors belong to the β-karyopherin family of proteins, with 22 members encoded in the human genome (3). The majority of β-karyopherins bind their cargoes directly, recognizing a linear nuclear localization or export signal and/or a specific tertiary/quaternary structural feature (4, 5).A fundamentally important type of a nuclear localization signal (NLS), comprising sequences rich in Arg-Ser and/or ArgAsp/Glu/Gly dipeptides (referred to as RS or RS-like domains), belongs to the family of Ser/Arg-rich (SR) proteins. These nuclear proteins also contain RNA recognition motif (RRM) domains and play essential roles in pre-mRNA splicing and 3′ processing and participate in transcription regulation, mRNA transport, translation, and nonsense-mediated mRNA decay (6). The splicing factors alternative splicing factor/splicing factor 2 (ASF/SF2) and SC35 along with the cleavage and polyadenylation specificity factor 6 (CPSF6, also known as CF-Im-68) are among the best-characterized metazoan SR proteins (7-10). The SR protein family can be further extended by inclusion of a structurally and functionally diverse group of nuclear proteins that possess RS repeats but lack RRM domains (11). The RS domains are processively phosphorylated on their Ser residues by a set of dedicated kinases (12-16). Phosphorylation of SR proteins is thought to...

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Section: Resultssupporting

confidence: 85%

“…A surprising discovery that a CPSF6 deletion mutant lacking the RS domain can potently inhibit HIV-1 replication through direct binding to capsid provides for a link between Tnpo3 and a viral component (34,35).…”

mentioning

confidence: 99%

Structural basis for nuclear import of splicing factors by human Transportin 3

Maertens

Cook

Wang

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

130

167

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“…Although we and others have shown that TRN-SR2 directly interacts with HIV IN (18,19,27,38,39), the mechanism of action has been questioned (19,23,36,40,41). Especially reports on a set of HIV capsid mutations (e.g.…”

mentioning

confidence: 94%

“…CPSF6 is a cellular protein involved in splicing and polyadenylation of pre-mRNA that carries an RS domain at its C terminus. Because CPSF6 binds HIV CA (40), it has been suggested that TRN-SR2 depletion might result in cytoplasmic accumulation of CPSF6, which in turn might perturb viral uncoating through CPSF6-CA binding, leading to an indirect block in nuclear import and restricted HIV replication (36,40,41). Still, the cytoplasmic accumulation of CPSF6 after TRN-SR2 knockdown is not always observed (36,41).…”

mentioning

confidence: 99%

The HIV-1 Integrase Mutant R263A/K264A Is 2-fold Defective for TRN-SR2 Binding and Viral Nuclear Import

Houwer

Demeulemeester

Thys

et al. 2014

Journal of Biological Chemistry

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Background: Whether the TRN-SR2/HIV-1 IN interaction mediates the nuclear import of HIV is controversial. Results: The replication-defective HIV integrase mutant INR263A/K264A displays a 2-fold reduction in interaction with TRN-SR2 and PIC nuclear import. Conclusion:The HIV-IN TRN-SR2 protein-protein interaction is important for HIV nuclear import. Significance: The IN/TRN-SR2 interaction interface is a potential target for future antiviral therapy.

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“…We and others have previously demonstrated that the small-molecule HIV-1-inhibitor PF74 prevents the binding of CPSF6 to HIV-1 capsid [6,17]. Because of the similar phenotypes observed for HIV-1-GFP infection when using BI-2 and PF74, we tested the ability CPSF6 to bind in vitro assembled HIV-1 CA-NC complexes in the presence of BI-2.…”

Section: Bi-2 Prevents the Binding Of Cpsf6 To In Vitro Assembled Hivmentioning

confidence: 97%

BI-2 destabilizes HIV-1 cores during infection and Prevents Binding of CPSF6 to the HIV-1 Capsid

et al. 2014

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Background: The recently discovered small-molecule BI-2 potently blocks HIV-1 infection. BI-2 binds to the N-terminal domain of HIV-1 capsid. BI-2 utilizes the same capsid pocket used by the small molecule PF74. Although both drugs bind to the same pocket, it has been proposed that BI-2 uses a different mechanism to block HIV-1 infection when compared to PF74. Findings: This work demonstrates that BI-2 destabilizes the HIV-1 core during infection, and prevents the binding of the cellular factor CPSF6 to the HIV-1 core. Conclusions: Overall this short-form paper suggests that BI-2 is using a similar mechanism to the one used by PF74 to block HIV-1 infection.

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CPSF6 Defines a Conserved Capsid Interface that Modulates HIV-1 Replication

Cited by 239 publications

References 44 publications

Structural basis for nuclear import of splicing factors by human Transportin 3

Structural basis for nuclear import of splicing factors by human Transportin 3

The HIV-1 Integrase Mutant R263A/K264A Is 2-fold Defective for TRN-SR2 Binding and Viral Nuclear Import

BI-2 destabilizes HIV-1 cores during infection and Prevents Binding of CPSF6 to the HIV-1 Capsid

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