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

Ayako Ohno,Yuushi Okumura,Takeshi Nikawa,Mariko Ariyoshi,Koji Kishimoto,Shigetada Teshima-Kondo,Takayuki Uchida,Nobuo Maita,Takanori Tabata,Kosuke Sugiura,Hikaru Nagano,Kyohei Arita,Reiko Nakao,Anayt Ulla

doi:10.26508/lsa.202000849

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.

Highlights

Mosaic serine protease large form (MSPL), and its splice variant TMPRSS13, was originally identified from a human lung cDNA library and is a member of the type II transmembrane serine proteases (TTSPs) (Kim et al, 2001; Kido & Okumura, 2008)
TTSPs comprise a transmembrane domain near the N-terminus and a trypsin-like serine protease domain (SPD) at the C-terminus
The two chains are linked by a disulfide bridge so that TTSPs remain bound to the cell membrane (Bugge et al, 2009)

Summary

Introduction

Mosaic serine protease large form (MSPL), and its splice variant TMPRSS13, was originally identified from a human lung cDNA library and is a member of the type II transmembrane serine proteases (TTSPs) (Kim et al, 2001; Kido & Okumura, 2008). TTSPs comprise a transmembrane domain near the N-terminus and a trypsin-like serine protease domain (SPD) at the C-terminus. TTSPs share a similar overall organization comprising an N-terminal cytoplasmic domain, transmembrane region, and stem/catalytic domains at the C terminus (Szabo & Bugge, 2008). Based on similarities in the domain structure, the SPD, TTSPs are classified into four subfamilies: hepsin/TMPRSS, matriptase, HAT/DESC, and corin (Szabo & Bugge, 2008, 2011; Antalis et al, 2011; Bottcher-Friebertshauser, 2018). The canonical LDLA domain contains ~40 amino acids and contains six conserved cysteine residues that are involved in the formation of disulfide bonds. The LDLA domain contains a calcium ion coordinated with six highly conserved residues near the C-terminus. The disulfide bonds and calcium-binding stabilize the overall structure of the LDLA domain (Daly et al, 1995)

Methods

Results

Conclusion