Avid Bioservices Inc (CDMO)

[biopharm]

The host-cell restriction factor SERINC5 restricts HIV-1 infectivity without altering the lipid composition and organization of viral particles

Received May 17, 2017.
Accepted June 28, 2017.


Authors
Birthe Trautz1,
Hannah Wiedemann2,
Christian Lüchtenborg2,
Virginia Pierini1,
Jan Kranich3,
Bärbel Glass1,
Hans-Georg Kräusslich1,
Thomas Brocker3,
Massimo Pizzato4,
Alessia Ruggieri1,
Britta Brügger2 and
Oliver T Fackler1*
1 University Hospital Heidelberg, Germany;
2 Heidelberg University Biochemistry Center (BZH), Germany;
3 Ludwig-Maximilians-Universität München;
4 University of Trento, Italy
?* Corresponding author; email: [e-mail]
Author contributions: OTF and BB designed the study and wrote the manuscript. BT and BG purified HIV-1 particles. CL and BB performed experiments for the quantitative lipid analysis. BT performed and analyzed experiments shown in Figures 1, 2, 3 and 5 and contributed to the preparation of all figures. VP and HW performed and analyzed experiments shown in Figure 4. JK, TB, MP, HGK and AR provided reagents and expertise. All authors approved the final manuscript.
Abstract

The host-cell restriction factor SERINC5 potently suppresses the infectivity of HIV-1 particles and is counteracted by the viral pathogenesis factor Nef. However, the molecular mechanism by which SERINC5 restricts HIV-1 particle infectivity is still unclear. Since SERINC proteins have been suggested to facilitate the incorporation of serine during the biosynthesis of membrane lipids and because lipid composition of HIV particles is a major determinant of the particles infectious potential, we tested whether SERINC5-mediated restriction of HIV particle infectivity involves alterations of membrane lipid composition. We produced and purified HIV-1 particles from SERINC5293T cells with very low endogenous SERINC5 levels under conditions in which ectopically expressed SERINC5 restricts HIV-1 infectivity and is antagonized by Nef, and analyzed both virions and producer cells with quantitative lipid MS. SERINC5 restriction and Nef antagonism were not associated with significant alterations in steady-state lipid composition of the producer cells and HIV particles. Sphingosine metabolism kinetics were also unaltered by SERINC5 expression. Moreover, levels of phosphatidylserine (PS) at the surface of HIV-1 particles, which may trigger uptake into non-productive internalization pathways in target cells, did not change upon expression of SERINC5 or Nef. Finally, saturating the PS-binding sites on HIV target cells did not affect SERINC5 restriction or Nef antagonism. These results (i) demonstrate that the restriction of HIV-1 particle infectivity by SERINC5 does not depend on alterations in lipid composition and organization of HIV-1 particles and (ii) suggest that channeling serine into lipid biosynthesis may not be a cardinal cellular function of SERINC5.
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http://m.jbc.org/content/early/2017/06/28/jbc.M117.797332.abstract