Electron tomography visualization of HIV-1 fusion with target cells using fusion inhibitors to trap the pre-hairpin intermediate
Abstract
Fusion of HIV-1 with the membrane of its target cell, an obligate first step in virus infectivity, is mediated by binding of the viral envelope (Env) spike protein to its receptors, CD4 and CCR5/CXCR4, on the cell surface. The process of viral fusion appears to be fast compared with viral egress and has not been visualized by EM. To capture fusion events, the process must be curtailed by trapping Env-receptor binding at an intermediate stage. We have used fusion inhibitors to trap HIV-1 virions attached to target cells by Envs in an extended pre-hairpin intermediate state. Electron tomography revealed HIV-1 virions bound to TZM-bl cells by 2–4 narrow spokes, with slightly more spokes present when evaluated with mutant virions that lacked the Env cytoplasmic tail. These results represent the first direct visualization of the hypothesized pre-hairpin intermediate of HIV-1 Env and improve our understanding of Env-mediated HIV-1 fusion and infection of host cells.
Additional Information
© 2020 Ladinsky et al. This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited. Received: 29 April 2020; Accepted: 21 July 2020; Published: 22 July 2020. The authors thank Annie Lynch for assistance with initial experiments, Erica Lee, Jennifer Keeffe, and the Beckman Institute Protein Expression Center at Caltech for preparing T1249-Fc, D5 IgG, and Z004 IgG, Sarah Apple and Nicholas Francis for preparing CPT31, Magnus Hoffmann for suggestions, and members of the Bjorkman and Kay laboratories for helpful discussions and critical review of the manuscript. This work was supported by the National Institute of General Medical Sciences (2 P50 AI150464) (to MSK and PJB). We thank the Caltech Kavli Nanoscience Institute for maintenance of the TF-30 electron microscope. Competing interests: Pamela J Bjorkman: Reviewing editor, eLife. The other authors declare that no competing interests exist. Author contributions: Mark S Ladinsky, Conceptualization, Data curation, Formal analysis, Supervision, Funding acquisition, Visualization, Methodology, Writing - original draft, Writing - review and editing; Priyanthi NP Gna- napragasam, Conceptualization, Resources, Data curation, Formal analysis, Visualization, Methodol- ogy, Writing - original draft, Writing - review and editing; Zhi Yang, Resources, Data curation, Methodology, Writing - review and editing; Anthony P West, Data curation, Formal analysis, Meth- odology; Michael S Kay, Conceptualization, Resources, Formal analysis, Methodology, Writing - review and editing; Pamela J Bjorkman, Conceptualization, Resources, Formal analysis, Supervision, Funding acquisition, Writing - original draft, Writing - review and editing. Data availability: Raw datasets are freely available upon request. Interested parties should contact ladinsky@caltech.edu, and we will place requested datasets onto an externally accessible Caltech Box Server. Requestors will then be provided with a direct URL link from which they can download the files at their convenience.Attached Files
Published - elife-58411-v2.pdf
Accepted Version - elife-58411-v1.pdf
Submitted - 2020.04.29.068775v1.full.pdf
Supplemental Material - elife-58411-supp-v1.zip
Supplemental Material - elife-58411-transrepform-v2.pdf
Supplemental Material - media-1.mp4
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Additional details
- Alternative title
- Electron tomography visualization of HIV-1 fusion with target cells using inhibitors to trap the prehairpin intermediate
- PMCID
- PMC7394545
- Eprint ID
- 102968
- Resolver ID
- CaltechAUTHORS:20200501-113540872
- NIH
- 2 P50 AI150464
- National Institute of General Medical Sciences
- Created
-
2020-05-01Created from EPrint's datestamp field
- Updated
-
2023-06-02Created from EPrint's last_modified field
- Caltech groups
- Kavli Nanoscience Institute, Division of Biology and Biological Engineering