Biological Sciences Division
Published July 20, 2023 | Version v1
Journal article Open

Antiviral HIV-1 SERINC restriction factors disrupt virus membrane asymmetry

Creators

  • 1. University of Miami
  • 2. University of Virginia
  • 3. Yale University
  • 4. University of Chicago
  • 5. National Cancer Institute
  • 6. Centre de Recherche du CHUM

Description

The host proteins SERINC3 and SERINC5 are HIV-1 restriction factors that reduce infectivity when incorporated into the viral envelope. The HIV-1 accessory protein Nef abrogates incorporation of SERINCs via binding to intracellular loop 4 (ICL4). Here, we determine cryoEM maps of full-length human SERINC3 and an ICL4 deletion construct, which reveal that hSERINC3 is comprised of two α-helical bundles connected by a ~ 40-residue, highly tilted, "crossmember" helix. The design resembles non-ATP-dependent lipid transporters. Consistently, purified hSERINCs reconstituted into proteoliposomes induce flipping of phosphatidylserine (PS), phosphatidylethanolamine and phosphatidylcholine. Furthermore, SERINC3, SERINC5 and the scramblase TMEM16F expose PS on the surface of HIV-1 and reduce infectivity, with similar results in MLV. SERINC effects in HIV-1 and MLV are counteracted by Nef and GlycoGag, respectively. Our results demonstrate that SERINCs are membrane transporters that flip lipids, resulting in a loss of membrane asymmetry that is strongly correlated with changes in Env conformation and loss of infectivity.

Data availability

The atomic coordinates and EM maps for WT hSERINC3-Fab and ΔICL4-hSERINC3-Fab have been deposited in the Protein Data Bank (www.rcsb.org) and EMDB (www.ebi.ac.uk/pdbe/emdb/) with accession codes 7RU6and EMD-24698 and 7RUG and EMD-24705, respectively. Source data are provided with this paper.

Scripts related to the exponential curve stripping analysis (Supplementary Fig. 11d) are available at https://github.com//eatatham/lipid_flipping. The Single-molecule Platform for Automated Real-Time Analysis (SPARTAN) software package can be obtained from Scott Blanchard at https://www.scottcblanchardlab.com/software. Custom Matlab scripts developed in the Mothes lab for smFRET data analysis are available upon request.

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Additional details

Identifiers

DOI
10.1038/s41467-023-39262-2
Other
oai:uchicago.tind.io:6797

Funding

National Institutes of Health
P50 AI15046
National Institutes of Health
U54 AI170856-01
National Cancer Institute
R01 AI154092
National Cancer Institute
R01 GM117372
National Cancer Institute
P01 AI150471
National Institutes of Health
AIDS Targeted Antiviral Program
CIHR
352417

UChicago Information

Division(s)
Biological Sciences Division
Department(s)
Biochemistry and Molecular Biology