This analysis showed about 45C50% sequence similarity (figure 1)

This analysis showed about 45C50% sequence similarity (figure 1). from the HR2 region, inhibited SARS-CoV contamination in the micromolar range. CP-1 bound with high affinity to a peptide from the HR1 region, NP-1. CP-1 alone had low -helicity and self-associated to form a trimer in phosphate buffer (pH 72). CP-1 and NP-1 mixed in equimolar concentrations formed a six-helix bundle, similar to the fusogenic core structure of HIV-1 gp41. Interpretation After binding to the target cell, the transmembrane spike protein might change conformation by association between the HR1 and HR2 regions to form an oligomeric structure, leading to fusion between the viral and target-cell membranes. At the prefusion intermediate state, CP-1 could bind to the HR1 region and interfere with the conformational changes, resulting in inhibition of SARS-CoV fusion with the target cells. CP-1 might be modifiable to increase its anti-SARS-CoV activity and could be further developed as an antiviral agent for treatment or prophylaxis of SARS-CoV contamination. Introduction The global outbreak of severe acute respiratory syndrome (SARS)1 has seriously threatened public health and socioeconomic stability. The disorder is usually caused by a novel coronavirus, SARS-associated coronavirus (SARS-CoV).2, 3, 4, 5, 6 Angiotensin-converting enzyme 2 is a functional receptor for the virus,7 but the mechanism by which SARS-CoV enters target cells is unclear. Elucidation of the fusogenic mechanism will provide important information for development of antiviral drugs and vaccines for treatment and prevention of SARS. SARS-CoV could have originated from wild animals because a very similar coronavirus has been isolated from animals such as Himalayan palm civets.8 This coronavirus shares genetic and structural properties with others, including murine hepatitis virus and bovine coronavirus.9, 10, 11, 12 For example, SARS-CoV also expresses abundant spike glycoprotein on its surface in a trimeric or dimeric structure, forming spikes about 20 nm long and 10 nm wide at the bulbous end.2, 3, 4, 5, 6 The spike protein of SARS-CoV, which is involved in virus binding, fusion, and entry, is a typical class I viral fusion protein, similar to the transmembrane glycoproteins of many enveloped viruses.13 Therefore, information obtained from studies of other enveloped viruses such as HIV-1 could be useful for investigation of the fusogenic mechanism mediated by the SARS-CoV spike protein. In the early 1990s, Wild and co-workers and our group discovered potent HIV-1 fusion-inhibitory peptides derived from the gp41 heptad repeat 1 and 2 (HR1 and HR2) regions, designated N-peptides and C-peptides, respectively.14, 15, 16 One of the C-peptides, T-20 (Trimeris, Research Triangle Park, NC, USA), was recently approved by the US Food and Drug Administration GSK3368715 as the first of a new class of anti-HIV drugsfusion inhibitors. Studies on the mechanism of action of these anti-HIV-1 peptides provided important information to elucidate the fusogenic mechanism mediated by HIV-1 gp41.17, 18, 19 After binding of gp120 to CD4 and a coreceptor, gp41 changes conformation via HR1 and HR2 conversation to form a fusogenic hexameric core structure, which brings the viral and target-cell membranes into close proximity, resulting in fusion between them. At the intermediate state, a C-peptide can bind the viral gp41 HR1 region and block formation of the six-helix bundle, thus inhibiting virus fusion with the target cell.20 The discovery of these HIV-1 fusion-inhibitory peptides launched a new line of investigation of viral fusogenic mechanisms and identification of antiviral peptides against infection by many other enveloped virusessimian21 and feline22 immunodefi-ciency viruses, Ebola virus,23 Newcastle disease virus,24 and respiratory syncytial virus.25 Similarly to HIV-1 gp41, the S2 domain of SARS-CoV spike protein contains HR1 and HR2 sequences, which tend to form a coiled-coil structure (figure 1 ). The aminoacid sequences of peptides derived from the HR1 and HR2 regions of SARS-CoV spike protein are similar to those from the HIV-1 gp41 HR1 and HR2 regions (physique 1); the similarity suggests that these two transmembrane envelope glycoproteins share a common mechanism mediating fusion between the viral and target-cell membranes. With a similar approach to that used for studying HIV-1 gp41, we designed and synthesised a series of peptides corresponding to the sequences of SARS-CoV spike protein HR1 and HR2 regions and used these peptides as probes to study the fusogenic mechanism of the virus and to identify antiviral peptides. Open in a separate window Physique 1 Schematic representation of SARS-CoV (strain TOR2) spike protein, sequence similarities between SARS-CoV and HIV-1 N-peptides and C-peptides, and helical wheels of HR1 and HR2 SP=signal peptide; TM=transmembrane domain name; CP=cytoplasmic domain name. Residue numbers of each region correspond to their positions in spike protein of.Only the CP-1 peptide (derived from the HR2 region) had strong inhibitory activity in tissue culture. the fusogenic core structure of HIV-1 gp41. Interpretation After binding to the target cell, the transmembrane spike protein might change conformation by association between the HR1 and HR2 regions to form an oligomeric structure, leading to fusion between the viral and target-cell membranes. At the prefusion intermediate state, CP-1 could bind to the HR1 region and interfere with the conformational changes, resulting in inhibition of SARS-CoV fusion with the target cells. CP-1 might be modifiable to increase its anti-SARS-CoV activity and could be further developed as an antiviral agent for treatment or prophylaxis of SARS-CoV contamination. Introduction The global outbreak of severe acute respiratory syndrome (SARS)1 has seriously threatened public health and socioeconomic stability. The disorder is usually caused by a novel coronavirus, SARS-associated coronavirus (SARS-CoV).2, GSK3368715 3, 4, 5, 6 Angiotensin-converting enzyme 2 is a functional receptor for the virus,7 but the mechanism by which SARS-CoV enters target cells is unclear. Elucidation of the fusogenic mechanism will provide important information for development of antiviral drugs and vaccines for treatment and prevention of SARS. SARS-CoV could have originated from wild animals because a very similar GSK3368715 coronavirus has been isolated from animals such as Himalayan palm civets.8 This coronavirus shares genetic and structural properties with others, including murine hepatitis virus and bovine coronavirus.9, 10, 11, 12 For example, SARS-CoV also expresses abundant spike glycoprotein on its surface in a trimeric or dimeric structure, forming spikes about 20 nm long and 10 nm wide at the bulbous end.2, 3, 4, 5, 6 The spike protein of SARS-CoV, which is involved in virus binding, fusion, and entry, is a typical class I viral fusion protein, similar to the transmembrane glycoproteins of many enveloped viruses.13 Therefore, information obtained from studies of other enveloped viruses such as HIV-1 could be useful for investigation of the fusogenic mechanism mediated by the SARS-CoV spike protein. In the early 1990s, Wild and co-workers and our group discovered potent HIV-1 fusion-inhibitory peptides derived from the gp41 heptad repeat 1 and 2 (HR1 and HR2) regions, designated N-peptides and C-peptides, respectively.14, 15, 16 One of the C-peptides, T-20 (Trimeris, Research Triangle Park, NC, USA), was recently approved by the US Food and Drug Administration as the first of a new class of anti-HIV drugsfusion inhibitors. Studies on the mechanism of action of these anti-HIV-1 peptides provided important information to elucidate the fusogenic mechanism mediated by HIV-1 gp41.17, 18, 19 After binding of gp120 to CD4 and a coreceptor, gp41 changes Rabbit polyclonal to Tyrosine Hydroxylase.Tyrosine hydroxylase (EC 1.14.16.2) is involved in the conversion of phenylalanine to dopamine.As the rate-limiting enzyme in the synthesis of catecholamines, tyrosine hydroxylase has a key role in the physiology of adrenergic neurons. conformation via HR1 and HR2 conversation to form a fusogenic hexameric core structure, which brings the viral and target-cell membranes into close proximity, resulting in fusion between them. At the intermediate state, a C-peptide can bind the viral gp41 HR1 region and block formation of the six-helix bundle, thus inhibiting virus fusion with the target cell.20 The discovery of these HIV-1 fusion-inhibitory peptides launched a new line of investigation of viral fusogenic mechanisms and identification of antiviral peptides against infection by many other enveloped virusessimian21 and feline22 immunodefi-ciency viruses, Ebola virus,23 Newcastle disease virus,24 and respiratory syncytial virus.25 Similarly to HIV-1 gp41, the S2 domain of SARS-CoV spike protein contains HR1 and HR2 sequences, which tend to form a coiled-coil structure (figure 1 ). The aminoacid sequences of peptides derived from the HR1 and HR2 regions of SARS-CoV spike protein are similar to those from the HIV-1 gp41 HR1 and HR2 regions (physique 1); the similarity suggests that these two transmembrane envelope glycoproteins.