Characterization of glycosylation profiles of HIV-1 transmitted/founder envelopes by mass spectrometry

J Virol. 2011 Aug;85(16):8270-84. doi: 10.1128/JVI.05053-11. Epub 2011 Jun 8.

Abstract

The analysis of HIV-1 envelope carbohydrates is critical to understanding their roles in HIV-1 transmission as well as in binding of envelope to HIV-1 antibodies. However, direct analysis of protein glycosylation by glycopeptide-based mass mapping approaches involves structural simplification of proteins with the use of a protease followed by an isolation and/or enrichment step before mass analysis. The successful completion of glycosylation analysis is still a major analytical challenge due to the complexity of samples, wide dynamic range of glycopeptide concentrations, and glycosylation heterogeneity. Here, we use a novel experimental workflow that includes an up-front complete or partial enzymatic deglycosylation step before trypsin digestion to characterize the glycosylation patterns and maximize the glycosylation coverage of two recombinant HIV-1 transmitted/founder envelope oligomers derived from clade B and C viruses isolated from acute infection and expressed in 293T cells. Our results show that both transmitted/founder Envs had similar degrees of glycosylation site occupancy as well as similar glycan profiles. Compared to 293T-derived recombinant Envs from viruses isolated from chronic HIV-1, transmitted/founder Envs displayed marked differences in their glycosylation site occupancies and in their amounts of complex glycans. Our analysis reveals that the glycosylation patterns of transmitted/founder Envs from two different clades (B and C) are more similar to each other than they are to the glycosylation patterns of chronic HIV-1 Envs derived from their own clades.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Glycoside Hydrolases / metabolism
  • Glycosylation
  • HEK293 Cells
  • HIV Infections / transmission
  • HIV Infections / virology
  • HIV-1 / chemistry*
  • HIV-1 / immunology
  • Humans
  • Mass Spectrometry / methods*
  • Sequence Alignment
  • Trypsin
  • env Gene Products, Human Immunodeficiency Virus / chemistry*

Substances

  • env Gene Products, Human Immunodeficiency Virus
  • Glycoside Hydrolases
  • Trypsin