The first critical step of HIV-1 infection is fusion of viral and target cell membranes mediated by envelope glycoprotein (Env). The mature Env spikes [trimeric (gp160)3, cleaved to (gp120/gp41)3] are the sole antigens on the virion surface. Conformational changes in gp120 when triggered by binding to receptor (CD4) and co- receptor (e.g., CCR5 or CXCR4) lead to a cascade of refolding events in gp41, and ultimately to membrane fusion. Vast amount of structural information is available for the ectodomain of Env, but much less is known regarding its transmembrane domain (TMD) and its membrane-proximal (MP) regions, including the membrane proximal external region (MPER) and the cytoplasmic tail (CT). We recently made an unexpected discovery that truncation of the CT domain drastically reshapes the antigenic surfaces of the Env ectodomain on the other side of the membrane. Deep understanding of the physical coupling (conformation and/or dynamics) between the CT and the ectodomain mediated by the TMD may guide Env-based immunogen design to induce broadly neutralizing antibodies (bnNabs). We thus hypothesize that the membrane-interacting domains (MPER, TMD and CT) of HIV-1 Env adopt defined structures which are critical for its stability, function and antigenicity. We have already completed a TMD structure at the atomic resolution using the state-of-the- art NMR technology. When reconstituted in bicelles that mimic lipid bilayer, the TMD forms a well-ordered trimer mainly stabilized by a tightly packed hydrophilic core near its C-terminal end that can potentially be influenced by the CT domain. In this application, we plan to combine structural biology approaches and functional assays to elucidate the roles of the membrane-interacting domains of HIV-1 Env. We will purse the following specific aims: 1) we will investigate TMD assembly of HIV and SIV Env and possible interaction with the fusion peptide; 2) we will provide structural information for the MP regions of Env in the context of membrane; 3) we will elucidate the role of the membrane-interacting domains of Env in its stability, function and antigenicity; 4) we will design trimer immunogens to mimic the native and functional HIV-1 Env spike..

Public Health Relevance

The membrane-interacting domains of HIV-1 envelope spike appear to play much greater roles in its stability, function and antigenicity than what has been appreciated previously. This proposal aims to determine atomic structures of these domains in a physiologically relevant environment, to assess their functional roles in viral infection and to rationally design immunogens for developing a safe and effective HIV-1 vaccine.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
1R01AI127193-01
Application #
9203214
Study Section
AIDS Molecular and Cellular Biology Study Section (AMCB)
Program Officer
Malaspina, Angela
Project Start
2016-05-20
Project End
2021-04-30
Budget Start
2016-05-20
Budget End
2017-04-30
Support Year
1
Fiscal Year
2016
Total Cost
Indirect Cost
Name
Children's Hospital Boston
Department
Type
DUNS #
076593722
City
Boston
State
MA
Country
United States
Zip Code
Shaik, Md Munan; Peng, Hanqin; Lu, Jianming et al. (2018) Structural basis of coreceptor recognition by HIV-1 envelope spike. Nature :
Fu, Qingshan; Shaik, Md Munan; Cai, Yongfei et al. (2018) Structure of the membrane proximal external region of HIV-1 envelope glycoprotein. Proc Natl Acad Sci U S A 115:E8892-E8899
Piai, Alessandro; Dev, Jyoti; Fu, Qingshan et al. (2017) Stability and Water Accessibility of the Trimeric Membrane Anchors of the HIV-1 Envelope Spikes. J Am Chem Soc 139:18432-18435
Cai, Yongfei; Karaca-Griffin, Selen; Chen, Jia et al. (2017) Antigenicity-defined conformations of an extremely neutralization-resistant HIV-1 envelope spike. Proc Natl Acad Sci U S A 114:4477-4482
Liu, Yuhang; Pan, Junhua; Cai, Yongfei et al. (2017) Conformational States of a Soluble, Uncleaved HIV-1 Envelope Trimer. J Virol 91:
Chen, Bing; Chou, James J (2017) Structure of the transmembrane domain of HIV-1 envelope glycoprotein. FEBS J 284:1171-1177
Dev, Jyoti; Park, Donghyun; Fu, Qingshan et al. (2016) Structural basis for membrane anchoring of HIV-1 envelope spike. Science 353:172-175