Article

The aromatic domain of the coronavirus class I viral fusion protein induces membrane permeabilization: Putative role during viral entry

Department of Biochemistry, Tulane University, New Orleans, Louisiana, United States
Biochemistry (Impact Factor: 3.19). 02/2005; 44(3):947-58. DOI: 10.1021/bi048515g
Source: PubMed

ABSTRACT Coronavirus (CoV) entry is mediated by the viral spike (S) glycoprotein, a class I viral fusion protein. During viral and target cell membrane fusion, the heptad repeat (HR) regions of the S2 subunit assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes; however, the exact mechanism is unclear. Here, we characterize an aromatic amino acid rich region within the ectodomain of the S2 subunit that both partitions into lipid membranes and has the capacity to perturb lipid vesicle integrity. Circular dichroism analysis indicated that peptides analogous to the aromatic domains of the severe acute respiratory syndrome (SARS)-CoV, mouse hepatitis virus (MHV) and the human CoV OC43 S2 subunits, did not have a propensity for a defined secondary structure. These peptides strongly partitioned into lipid membranes and induced lipid vesicle permeabilization at peptide/lipid ratios of 1:100 in two independent leakage assays. Thus, partitioning of the peptides into the lipid interface is sufficient to disorganize membrane integrity. Our study of the S2 aromatic domain of three CoVs provides supportive evidence for a functional role of this region. We propose that, when aligned with the fusion peptide and transmembrane domains during membrane apposition, the aromatic domain of the CoV S protein functions to perturb the target cell membrane and provides a continuous track of hydrophobic surface, resulting in lipid-membrane fusion and subsequent viral nucleocapsid entry.

0 Bookmarks
 · 
69 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Severe acute respiratory syndrome-associated coronavirus (SARS-CoV) poses a serious public health hazard. The S2 subunit of the S glycoprotein of SARS-CoV carries out fusion between the virus and the host cells. However, the exact mechanism of the cell fusion process is not well understood. Current model suggests that a conformational transition, upon receptor recognition, of the two heptad core regions of S2 may expose the hydrophobic fusogenic peptide or fusion peptide for membrane insertion. Three regions of the S2 subunit have been proposed to be involved in cell-cell fusion. The N-terminal fusion peptide (FP, residues 770-788), an internal fusion peptide (IFP, residues 873-888) and the pre-transmembrane region (PTM, residues 1185-1202) demonstrated interactions with model lipid membranes and potentially involved in the fusion process. Here, we have determined atomic resolution structures of these three peptides in DPC detergent micelles by solution NMR. FP assumes α-helical conformation with significant distortion at the central Gly residues; enabling a close packing among sidechains of aromatic residues including W, Y and F. The 3-D structure of PMT is characterized by a helix-loop-helix with extensive aromatic interactions within the helices. IFP adopts a rather straight α-helical conformation defined by packing among sidechains of aromatic and aliphatic residues. Paramagnetic spin labeled NMR has demonstrated surface localization of PMT whereas FP and IFP inserted into the micelles. Collectively, data presented in this study will aid in understanding fusion mechanism of SARS-CoV. Copyright © 2014. Published by Elsevier B.V.
    Biochimica et Biophysica Acta (BBA) - Biomembranes 12/2014; 1848(2). DOI:10.1016/j.bbamem.2014.11.025 · 3.43 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: There are many peptides known that inhibit the entry of enveloped viruses into cells, including one peptide that is successfully being used in the clinic as a drug. In this review, we discuss the discovery, antiviral activity and mechanism of action of such peptides. While peptide entry inhibitors have been discovered by a wide variety of approaches (structure-based, accidental, intentional, rational and brute force) we show here that they share a common physical chemical property: they are at least somewhat hydrophobic and/or amphipathic and have a propensity to interact with membrane interfaces. We propose that this propensity drives a shared mechanism of action for many peptide entry inhibitors, involving direct interactions with viral and cellular membranes, as well as interactions with the complex hydrophobic protein/lipid interfaces that are exposed, at least transiently, during virus-cell fusion. By interacting simultaneously with the membrane interfaces and other critical hydrophobic surfaces, we hypothesize that peptide entry inhibitors can act by changing the physical chemistry of the membranes, and the fusion protein interfaces bridging them, and by doing so interfere with the fusion of cellular and viral membranes. Based on this idea, we propose that an approach that focuses on the interfacial hydrophobicity of putative entry inhibitors, could lead to the efficient discovery of novel, broad-spectrum viral entry inhibitors.
    Biochimica et Biophysica Acta 04/2014; DOI:10.1016/j.bbamem.2014.04.015 · 4.66 Impact Factor
  • Source

Preview

Download
0 Downloads
Available from