title: Inhibition of proprotein convertases abrogates processing of the middle eastern respiratory syndrome coronavirus spike protein in infected cells but does not reduce viral infectivity.
abstract: Middle East respiratory syndrome coronavirus (MERS-CoV) infection is associated with a high case-fatality rate, and the potential pandemic spread of the virus is a public health concern. The spike protein of MERS-CoV (MERS-S) facilitates viral entry into host cells, which depends on activation of MERS-S by cellular proteases. Proteolytic activation of MERS-S during viral uptake into target cells has been demonstrated. However, it is unclear whether MERS-S is also cleaved during S protein synthesis in infected cells and whether cleavage is required for MERS-CoV infectivity. Here, we show that MERS-S is processed by proprotein convertases in MERS-S-transfected and MERS-CoV-infected cells and that several RXXR motifs located at the border between the surface and transmembrane subunit of MERS-S are required for efficient proteolysis. However, blockade of proprotein convertases did not impact MERS-S-dependent transduction of target cells expressing high amounts of the viral receptor, DPP4, and did not modulate MERS-CoV infectivity. These results show that MERS-S is a substrate for proprotein convertases and demonstrate that processing by these enzymes is dispensable for S protein activation. Efforts to inhibit MERS-CoV infection by targeting host cell proteases should therefore focus on enzymes that process MERS-S during viral uptake into target cells.
authors: Infection Biology Unit, German Primate Center, Göttingen.
authors: Stefanie
authors: S
authors: Gierer
authors: Institute of Virology, University of Bonn Medical Center.
authors: Marcel A
authors: MA
authors: Müller
authors: Infection Biology Unit, German Primate Center, Göttingen.
authors: Adeline
authors: A
authors: Heurich
authors: Institute of Virology, University of Bonn Medical Center.
authors: Daniel
authors: D
authors: Ritz
authors: Infection Biology Unit, German Primate Center, Göttingen.
authors: Benjamin L
authors: BL
authors: Springstein
authors: Infection Biology Unit, German Primate Center, Göttingen Institute for Cellular Chemistry, Hannover Medical School, Germany.
authors: Christina B
authors: CB
authors: Karsten
authors: Infection Biology Unit, German Primate Center, Göttingen.
authors: Alexander
authors: A
authors: Schendzielorz
authors: Infection Biology Unit, German Primate Center, Göttingen.
authors: Kerstin
authors: K
authors: Gnirß
authors: Institute of Virology, University of Bonn Medical Center.
authors: Christian
authors: C
authors: Drosten
authors: Infection Biology Unit, German Primate Center, Göttingen.
authors: Stefan
authors: S
authors: Pöhlmann
mesh_terms: D000595:Amino Acid Sequence; D000998:Antiviral Agents / Q000494:pharmacology; D017934:Coronavirus / Q000502:physiology*; D004353:Drug Evaluation, Preclinical; D057809:HEK293 Cells; D006801:Humans; D008969:Molecular Sequence Data; D043484:Proprotein Convertases / Q000037:antagonists & inhibitors*; D011480:Protease Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D059748:Proteolysis; D064370:Spike Glycoprotein, Coronavirus / Q000737:chemistry / Q000378:metabolism*; D053586:Virus Internalization
chemical_list: D000998:Antiviral Agents; D011480:Protease Inhibitors; D064370:Spike Glycoprotein, Coronavirus; D043484:Proprotein Convertases
keywords: MERS-coronavirus; TMPRSS2; activation; proprotein convertase; protease; spike; trypsin