Crystal structure of inhibitor-bound human MSPL that can activate high pathogenic avian influenza

Abstract

Infection of certain influenza viruses is triggered when its HA is cleaved by host cell proteases such as proprotein convertases and type II transmembrane serine proteases (TTSP). HA with a monobasic motif is cleaved by trypsin-like proteases, including TMPRSS2 and HAT, whereas the multibasic motif found in high pathogenicity avian influenza HA is cleaved by furin, PC5/6, or MSPL. MSPL belongs to the TMPRSS family and preferentially cleaves [R/K]-K-K-R↓ sequences. Here, we solved the crystal structure of the extracellular region of human MSPL in complex with an irreversible substrate-analog inhibitor. The structure revealed three domains clustered around the C-terminal α-helix of the SPD. The inhibitor structure and its putative model show that the P1-Arg inserts into the S1 pocket, whereas the P2-Lys and P4-Arg interacts with the Asp/Glu-rich 99-loop that is unique to MSPL. Based on the structure of MSPL, we also constructed a homology model of TMPRSS2, which is essential for the activation of the SARS-CoV-2 spike protein and infection. The model may provide the structural insight for the drug development for COVID-19.

Transmembrane serine protease TMPRSS2 implicated in SARS-CoV-2 infection is autoactivated intracellularly and requires N-glycosylation for regulation

“…In our 3-D protein modeling, modules in the TMPRSS2 extracellular region appeared to fold independently. The results are consistent with recently published structures of a partial TMPRSS2 extracellular fragment without the LDLR domain ( 60 ) and the full-length extracellular region of TMPRSS13 ( 76 ). N286 is located between the SRCR and the protease domains.…”

Spike substitution T813S increases Sarbecovirus fusogenicity by enhancing the usage of TMPRSS2

“…To test this hypothesis, we investigated the impact of S813T mutation on the S2’ site cleavage on VSVpp and S proteins by TPCK-trypsin, the serine protease domain of which has extremely high homology with TMPRSS2 [ 52 ] and previous studies have used it to observe the S2’ formation [ 53 , 54 ]. WB analyses showed that S813T mutation had the most significant effect on S2’ cleavage compared with other point mutations in IFP ( Fig 6B left).…”

Structural basis of TMPRSS2 zymogen activation and recognition by the HKU1 seasonal coronavirus

“…As a consequence, the S1 site is formed without alteration of the catalytic triad. Of note, the conformation of loops 1 and 2 in TMPRSS2 S441A -Cl is the same those of active forms of hepsin 33 and TMPRSS13 (also called MSPL) 34 (Figure SI4C).…”

“…Of note, the conformation of loops 1 and 2 in TMPRSS2 S441A -Cl is the same those of active forms of hepsin 33 and TMPRSS13 (also called MSPL) 34 (Figure SI4C).…”