A Long Cytoplasmic Loop Governs the Sensitivity of the Anti-viral Host Protein SERINC5 to HIV-1 Nef

Dai, Weiwei; Usami, Yoshiko; Wu, Ying; Göttlinger, Heinrich G.

doi:10.1016/j.celrep.2017.12.082

Cited by 48 publications

(60 citation statements)

References 33 publications

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“…Because these viral antagonists of the Serinc proteins presumably function by affecting membrane trafficking, whether the presence or absence of an intact PSAC motif in Serinc proteins affects their activity remains an interesting and open question. So far, we have shown only that the presence or absence of an intact PSAC has no influence on the activity of a single HIV-1 Nef protein as an antagonist of Serinc3, even though the analogous cytoplasmic loop has recently been shown to be a determinant of the susceptibility of Serinc5 to Nef proteins (36).…”

Section: Discussionmentioning

confidence: 90%

Phosphoserine acidic cluster motifs bind distinct basic regions on the μ subunits of clathrin adaptor protein complexes

Singh

Stoneham

Lim

et al. 2018

Journal of Biological Chemistry

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Protein trafficking in the endosomal system involves the recognition of specific signals within the cytoplasmic domains (CDs) of transmembrane proteins by clathrin adaptors. One such signal is the phosphoserine acidic cluster (PSAC), the prototype of which is in the endoprotease furin. How PSACs are recognized by clathrin adaptors has been controversial. We reported previously that HIV-1 Vpu, which modulates cellular immunoreceptors, contains a PSAC that binds to the μ subunits of clathrin adaptor protein (AP) complexes. Here, we show that the CD of furin binds the μ subunits of AP-1 and AP-2 in a phosphorylation-dependent manner. Moreover, we identify a potential PSAC in a cytoplasmic loop of the cellular transmembrane Serinc3, an inhibitor of the infectivity of retroviruses. The two serines within the PSAC of Serinc3 are phosphorylated by casein kinase II and mediate interaction with the μ subunits The sites of these serines vary among mammals in a manner suggesting host-pathogen conflict, yet the Serinc3 PSAC seems dispensable for anti-HIV activity and for counteraction by HIV-1 Nef. The CDs of Vpu and furin and the PSAC-containing loop of Serinc3 each bind the μ subunit of AP-2 (μ2) with similar affinities, but they appear to utilize different basic regions on μ2. The Serinc3 loop requires a region previously reported to bind the acidic plasma membrane lipid phosphatidylinositol 4,5-bisphosphate. These data suggest that the PSACs within different proteins recognize different basic regions on the μ surface, providing the potential to inhibit the activity of viral proteins without necessarily affecting cellular protein trafficking.

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Section: Discussionmentioning

confidence: 90%

Phosphoserine acidic cluster motifs bind distinct basic regions on the μ subunits of clathrin adaptor protein complexes

Singh

Stoneham

Lim

et al. 2018

Journal of Biological Chemistry

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“…In contrast to other antiviral restriction factors, SERINC5 is highly conserved and orthologs from various vertebrate species display antiretroviral activity [ 10 ]. Recently, however, it has been shown that frog SERINC5 is resistant to HIV-1 Nef and further demonstrated that the sensitivity is governed by the intracellular loop 4 (ICL4) of the restriction factor [ 39 ]. We confirmed these previous findings for HIV-1 NL4-3 Nef, as well as the finding that SIVmac239 Nef is broadly active and capable of counteracting frog SERINC5 ( Fig 3 ).…”

Section: Resultsmentioning

confidence: 99%

“…The pBJ6 vector expressing HA-tagged SERINC5, pBJ5 vector expressing HA-tagged MLV glycoGag as well as the pSERINC-GFP vectors have been previously reported [ 8 ]. Human SERINC5 mutants L350A and I352A, as well as frog and zebrafish orthologs and frog/human SERINC5 chimeras were described before [ 39 ].…”

Section: Methodsmentioning

confidence: 99%

SIVcol Nef counteracts SERINC5 by promoting its proteasomal degradation but does not efficiently enhance HIV-1 replication in human CD4+ T cells and lymphoid tissue

et al. 2018

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SERINC5 is a host restriction factor that impairs infectivity of HIV-1 and other primate lentiviruses and is counteracted by the viral accessory protein Nef. However, the importance of SERINC5 antagonism for viral replication and cytopathicity remained unclear. Here, we show that the Nef protein of the highly divergent SIVcol lineage infecting mantled guerezas (Colobus guereza) is a potent antagonist of SERINC5, although it lacks the CD4, CD3 and CD28 down-modulation activities exerted by other primate lentiviral Nefs. In addition, SIVcol Nefs decrease CXCR4 cell surface expression, suppress TCR-induced actin remodeling, and counteract Colobus but not human tetherin. Unlike HIV-1 Nef proteins, SIVcol Nef induces efficient proteasomal degradation of SERINC5 and counteracts orthologs from highly divergent vertebrate species, such as Xenopus frogs and zebrafish. A single Y86F mutation disrupts SERINC5 and tetherin antagonism but not CXCR4 down-modulation by SIVcol Nef, while mutation of a C-proximal di-leucine motif has the opposite effect. Unexpectedly, the Y86F change in SIVcol Nef had little if any effect on viral replication and CD4+ T cell depletion in preactivated human CD4+ T cells and in ex vivo infected lymphoid tissue. However, SIVcol Nef increased virion infectivity up to 10-fold and moderately increased viral replication in resting peripheral blood mononuclear cells (PBMCs) that were first infected with HIV-1 and activated three or six days later. In conclusion, SIVcol Nef lacks several activities that are conserved in other primate lentiviruses and utilizes a distinct proteasome-dependent mechanism to counteract SERINC5. Our finding that evolutionarily distinct SIVcol Nefs show potent anti-SERINC5 activity supports a relevant role of SERINC5 antagonism for viral fitness in vivo. Our results further suggest this Nef function is particularly important for virion infectivity under conditions of limited CD4+ T cell activation.

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“…Full-length SERINC5 cDNA sequences were amplified from RNA extracted from human and rhesus macaque PBMCs by RT-PCR and cloned into the Not I and Bam HI sites of pQCXIH. Sequences encoding an HA epitope tag were introduced into an extracellular loop of SERINC5 between residues 290 and 291 as previously described [57]. Plasmid DNA constructs for the expression of firefly luciferase from a promoter with three NF-κB binding sites and Gaussia luciferase were provided by Dr. Daniel Sauter (Ulm University Medical Center, Ulm, Germany) [41].…”

Section: Plasmid Dna Constructsmentioning

confidence: 99%

Loss of tetherin antagonism by Nef impairs SIV replication during acute infection of rhesus macaques

et al. 2020

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Most simian immunodeficiency viruses use Nef to counteract the tetherin proteins of their nonhuman primate hosts. Nef also downmodulates cell-surface CD4 and MHC class I (MHC I) molecules and enhances viral infectivity by counteracting SERINC5. We previously demonstrated that tetherin antagonism by SIV Nef is genetically separable from CD4-and MHC I-downmodulation. Here we show that disruption of tetherin antagonism by Nef impairs virus replication during acute SIV infection of rhesus macaques. A combination of mutations was introduced into the SIV mac 239 genome resulting in three amino acid substitutions in Nef that impair tetherin antagonism, but not CD3-, CD4-or MHC I-downmodulation. Further characterization of this mutant (SIV mac 239 AAA) revealed that these changes also result in partial sensitivity to SERINC5. Separate groups of four rhesus macaques were infected with either wild-type SIV mac 239 or SIV mac 239 AAA , and viral RNA loads in plasma and sequence changes in the viral genome were monitored. Viral loads were significantly lower during acute infection in animals infected with SIV mac 239 AAA than in animals infected with wild-type SIV mac 239. Sequence analysis of the virus population in plasma confirmed that the substitutions in Nef were retained during acute infection; however, changes were observed by week 24 post-infection that fully restored anti-tetherin activity and partially restored anti-SERINC5 activity. These observations reveal overlap in the residues of SIV Nef required for counteracting tetherin and SERINC5 and selective pressure to overcome these restriction factors in vivo.

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A Long Cytoplasmic Loop Governs the Sensitivity of the Anti-viral Host Protein SERINC5 to HIV-1 Nef

Cited by 48 publications

References 33 publications

Phosphoserine acidic cluster motifs bind distinct basic regions on the μ subunits of clathrin adaptor protein complexes

Phosphoserine acidic cluster motifs bind distinct basic regions on the μ subunits of clathrin adaptor protein complexes

SIVcol Nef counteracts SERINC5 by promoting its proteasomal degradation but does not efficiently enhance HIV-1 replication in human CD4+ T cells and lymphoid tissue

Loss of tetherin antagonism by Nef impairs SIV replication during acute infection of rhesus macaques

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