Dataset Information

Crystal structure of the simian immunodeficiency virus (SIV) gp41 core: conserved helical interactions underlie the broad inhibitory activity of gp41 peptides.

ABSTRACT: The gp41 subunit of the envelope protein complex from human and simian immunodeficiency viruses (HIV and SIV) mediates membrane fusion during viral entry. The crystal structure of the HIV-1 gp41 ectodomain core in its proposed fusion-active state is a six-helix bundle. Here we have reconstituted the core of the SIV gp41 ectodomain with two synthetic peptides called SIV N36 and SIV C34, which form a highly helical trimer of heterodimers. The 2.2 A resolution crystal structure of this SIV N36/C34 complex is very similar to the analogous structure in HIV-1 gp41. In both structures, three N36 helices form a central trimeric coiled coil. Three C34 helices pack in an antiparallel orientation into highly conserved, hydrophobic grooves along the surface of this coiled coil. The conserved nature of the N36-C34 interface suggests that the HIV-1 and SIV peptides are functionally interchangeable. Indeed, a heterotypic complex between HIV-1 N36 and SIV C34 peptides is highly helical and stable. Moreover, as with HIV-1 C34, the SIV C34 peptide is a potent inhibitor of HIV-1 infection. These results identify conserved packing interactions between the N and C helices of gp41 and have implications for the development of C peptide analogs with broad inhibitory activity.

SUBMITTER: Malashkevich VN

PROVIDER: S-EPMC21304 | biostudies-literature | 1998 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Crystal structure of the simian immunodeficiency virus (SIV) gp41 core: conserved helical interactions underlie the broad inhibitory activity of gp41 peptides.

Malashkevich V N VN Chan D C DC Chutkowski C T CT Kim P S PS

Proceedings of the National Academy of Sciences of the United States of America 19980801 16

The gp41 subunit of the envelope protein complex from human and simian immunodeficiency viruses (HIV and SIV) mediates membrane fusion during viral entry. The crystal structure of the HIV-1 gp41 ectodomain core in its proposed fusion-active state is a six-helix bundle. Here we have reconstituted the core of the SIV gp41 ectodomain with two synthetic peptides called SIV N36 and SIV C34, which form a highly helical trimer of heterodimers. The 2.2 A resolution crystal structure of this SIV N36/C34 ...[more]

PMID: 9689046

Similar Datasets

Project description:UnlabelledHuman immunodeficiency virus (HIV) transmission typically results from infection by a single transmitted/founder (T/F) variant. Are T/F variants chosen uniformly at random from the donor pool, or are they selected based on advantageous traits facilitating transmission? Finding evidence for selection during transmission is of particular interest, because it would indicate that phenotypic and/or genetic properties of the viruses might be harnessed as potential vaccine targets or immunotherapies. Here, we systematically evaluated the differences between the Env proteins of simian immunodeficiency virus/simian HIV (SIV/SHIV) stock and T/F variants in search of "signature" sites of transmission. We also surveyed residue preferences in HIV at the SIV/SHIV signature sites. Four sites of gp120 showed significant selection, and an additional two sites showed a similar trend. Therefore, the six sites clearly differentiate T/F viruses from the majority of circulating variants in the stocks. The selection of SIV/SHIV could be inferred reasonably across both vaccinated and unvaccinated subjects, with infections resulting from vaginal, rectal, and intravenous routes of transmission and regardless of viral dosage. The evidence for selection in SIV and SHIV T/F variants is strong and plentiful, and in HIV the evidence is suggestive though commensurate with the availability of suitable data for analysis. Two of the signature residues are completely conserved across the SIV, SHIV, and HIV variants we examined. Five of the signature residues map to the C1 region of gp120 and one to the signal peptide. Our data raise the possibility that C1, while governing the association between gp120 and gp41, modulates transmission efficiency, replicative fitness, and/or host cell tropism at the level of virus-cell attachment and entry.ImportanceThe present study finds significant evidence of selection on gp120 molecules of SIV/SHIV T/F viruses. The data provide ancillary evidence suggesting the same sites are under selection in HIV. Our findings suggest that the signature residues are involved in increasing the transmissibility of infecting viruses; therefore, they are potential targets for developing a vaccine or other protective measures. A recent study identified the same T/F signature motif but interpreted it as an effect of neutralization resistance. Here, we show that the T/F motif has broader functional significance beyond neutralization sensitivity, because it is present in nonimmune subjects. Also, a vaccine regimen popular in animal trials might have increased the transmission of variants with otherwise low transmission fitness. Our observations might explain why many animal vaccine trials have not faithfully predicted outcomes in human vaccine trials and suggest that current practices in vaccine design need to be reexamined accordingly.

Project description:The monoclonal antibodies (MAbs) NCI05 and NCI09, isolated from a vaccinated macaque that was protected from multiple simian immunodeficiency virus (SIV) challenges, both target an overlapping, conformationally dynamic epitope in SIV envelope variable region 2 (V2). Here, we show that NCI05 recognizes a CH59-like coil/helical epitope, whereas NCI09 recognizes a β-hairpin linear epitope. In vitro, NCI05 and, to a lesser extent, NCI09 mediate the killing of SIV-infected cells in a CD4-dependent manner. Compared to NCI05, NCI09 mediates higher titers of antibody-dependent cellular cytotoxicity (ADCC) to gp120-coated cells, as well as higher levels of trogocytosis, a monocyte function that contributes to immune evasion. We also found that passive administration of NCI05 or NCI09 to macaques did not affect the risk of SIVmac251 acquisition compared to controls, demonstrating that these anti-V2 antibodies alone are not protective. However, NCI05 but not NCI09 mucosal levels strongly correlated with delayed SIVmac251 acquisition, and functional and structural data suggest that NCI05 targets a transient state of the viral spike apex that is partially opened, compared to its prefusion-closed conformation. IMPORTANCE Studies suggest that the protection against SIV/simian-human immunodeficiency virus (SHIV) acquisition afforded by the SIV/HIV V1 deletion-containing envelope immunogens, delivered by the DNA/ALVAC vaccine platform, requires multiple innate and adaptive host responses. Anti-inflammatory macrophages and tolerogenic dendritic cells (DC-10), together with CD14+ efferocytes, are consistently found to correlate with a vaccine-induced decrease in the risk of SIV/SHIV acquisition. Similarly, V2-specific antibody responses mediating ADCC, Th1 and Th2 cells expressing no or low levels of CCR5, and envelope-specific NKp44+ cells producing interleukin 17 (IL-17) also are reproducible correlates of decreased risk of virus acquisition. We focused on the function and the antiviral potential of two monoclonal antibodies (NCI05 and NCI09) isolated from vaccinated animals that differ in antiviral function in vitro and recognize V2 in a linear (NCI09) or coil/helical (NCI05) conformation. We demonstrate that NCI05, but not NCI09, delays SIVmac251 acquisition, highlighting the complexity of antibody responses to V2.

Dataset Information

Crystal structure of the simian immunodeficiency virus (SIV) gp41 core: conserved helical interactions underlie the broad inhibitory activity of gp41 peptides.

Publications

Crystal structure of the simian immunodeficiency virus (SIV) gp41 core: conserved helical interactions underlie the broad inhibitory activity of gp41 peptides.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets