6y3y
Human Coronavirus HKU1 Haemagglutinin-Esterase
Structural highlights
FunctionHEMA_CVHN1 Structural protein that makes short spikes at the surface of the virus. Contains receptor binding and receptor-destroying activities. Mediates de-O-acetylation of N-acetyl-4-O-acetylneuraminic acid, which is probably the receptor determinant recognized by the virus on the surface of erythrocytes and susceptible cells. This receptor-destroying activity is important for virus release as it probably helps preventing self-aggregation and ensures the efficient spread of the progeny virus from cell to cell. May serve as a secondary viral attachment protein for initiating infection, the spike protein being the major one. May become a target for both the humoral and the cellular branches of the immune system. Publication Abstract from PubMedThe human betacoronaviruses HKU1 and OC43 (subgenus Embecovirus) arose from separate zoonotic introductions, OC43 relatively recently and HKU1 apparently much longer ago. Embecovirus particles contain two surface projections called spike (S) and haemagglutinin-esterase (HE), with S mediating receptor binding and membrane fusion, and HE acting as a receptor-destroying enzyme. Together, they promote dynamic virion attachment to glycan-based receptors, specifically 9-O-acetylated sialic acid. Here we present the cryo-EM structure of the ~80 kDa, heavily glycosylated HKU1 HE at 3.4 A resolution. Comparison with existing HE structures reveals a drastically truncated lectin domain, incompatible with sialic acid binding, but with the structure and function of the esterase domain left intact. Cryo-EM and mass spectrometry analysis reveals a putative glycan shield on the now redundant lectin domain. The findings further our insight into the evolution and host adaptation of human embecoviruses, and demonstrate the utility of cryo-EM for studying small, heavily glycosylated proteins. Cryo-EM structure of coronavirus-HKU1 haemagglutinin esterase reveals architectural changes arising from prolonged circulation in humans.,Hurdiss DL, Drulyte I, Lang Y, Shamorkina TM, Pronker MF, van Kuppeveld FJM, Snijder J, de Groot RJ Nat Commun. 2020 Sep 16;11(1):4646. doi: 10.1038/s41467-020-18440-6. PMID:32938911[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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