title: Structure and inhibition of the SARS coronavirus envelope protein ion channel.
abstract: The envelope (E) protein from coronaviruses is a small polypeptide that contains at least one alpha-helical transmembrane domain. Absence, or inactivation, of E protein results in attenuated viruses, due to alterations in either virion morphology or tropism. Apart from its morphogenetic properties, protein E has been reported to have membrane permeabilizing activity. Further, the drug hexamethylene amiloride (HMA), but not amiloride, inhibited in vitro ion channel activity of some synthetic coronavirus E proteins, and also viral replication. We have previously shown for the coronavirus species responsible for severe acute respiratory syndrome (SARS-CoV) that the transmembrane domain of E protein (ETM) forms pentameric alpha-helical bundles that are likely responsible for the observed channel activity. Herein, using solution NMR in dodecylphosphatidylcholine micelles and energy minimization, we have obtained a model of this channel which features regular alpha-helices that form a pentameric left-handed parallel bundle. The drug HMA was found to bind inside the lumen of the channel, at both the C-terminal and the N-terminal openings, and, in contrast to amiloride, induced additional chemical shifts in ETM. Full length SARS-CoV E displayed channel activity when transiently expressed in human embryonic kidney 293 (HEK-293) cells in a whole-cell patch clamp set-up. This activity was significantly reduced by hexamethylene amiloride (HMA), but not by amiloride. The channel structure presented herein provides a possible rationale for inhibition, and a platform for future structure-based drug design of this potential pharmacological target.
authors: School of Biological Sciences, Nanyang Technological University, Singapore. kpervushin@ntu.edu.sg
authors: Konstantin
authors: K
authors: Pervushin
authors: Edward
authors: E
authors: Tan
authors: Krupakar
authors: K
authors: Parthasarathy
authors: Xin
authors: X
authors: Lin
authors: Feng Li
authors: FL
authors: Jiang
authors: Dejie
authors: D
authors: Yu
authors: Ardcharaporn
authors: A
authors: Vararattanavech
authors: Tuck Wah
authors: TW
authors: Soong
authors: Ding Xiang
authors: DX
authors: Liu
authors: Jaume
authors: J
authors: Torres
mesh_terms: D000584:Amiloride / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D002460:Cell Line; D006801:Humans; D007473:Ion Channels / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D018408:Patch-Clamp Techniques; D011485:Protein Binding; D011487:Protein Conformation; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D015203:Reproducibility of Results; D045473:Severe acute respiratory syndrome-related coronavirus / Q000737:chemistry* / Q000378:metabolism; D014759:Viral Envelope Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000378:metabolism
chemical_list: D007473:Ion Channels; D014759:Viral Envelope Proteins; C057360:5-(N,N-hexamethylene)amiloride; D000584:Amiloride