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Directed Evolution-Driven Increase of Structural Plasticity Is a Prerequisite for Binding the Complement Lectin Pathway Blocking MASP-Inhibitor Peptides
journal contribution
posted on 2022-04-05, 00:03 authored by Zsolt Dürvanger, Eszter Boros, Zoltán Attila Nagy, Rózsa Hegedüs, Márton Megyeri, József Dobó, Péter Gál, Gitta Schlosser, Annamária
F. Ángyán, Zoltán Gáspári, András Perczel, Veronika Harmat, Gábor Mező, Dóra K. Menyhárd, Gábor PálMASP-1 and MASP-2
are key activator proteases of the complement
lectin pathway. The first specific mannose-binding lectin-associated
serine protease (MASP) inhibitors had been developed from the 14-amino-acid
sunflower trypsin inhibitor (SFTI) peptide by phage display, yielding
SFTI-based MASP inhibitors, SFMIs. Here, we present the crystal structure
of the MASP-1/SFMI1 complex that we analyzed in comparison to other
existing MASP-1/2 structures. Rigidified backbone structure has long
been accepted as a structural prerequisite for peptide inhibitors
of proteases. We found that a hydrophobic cluster organized around
the P2 Thr residue is essential for the structural stability of wild-type
SFTI. We also found that the same P2 Thr prevents binding of the rigid
SFTI-like peptides to the substrate-binding cleft of both MASPs as
the cleft is partially blocked by large gatekeeper enzyme loops. Directed
evolution removed this obstacle by replacing the P2 Thr with a Ser,
providing the SFMIs with high-degree structural plasticity, which
proved to be essential for MASP inhibition. To gain more insight into
the structural criteria for SFMI-based MASP-2 inhibition, we systematically
modified MASP-2-specific SFMI2 by capping its two termini and by replacing
its disulfide bridge with varying length thioether linkers. By doing
so, we also aimed to generate a versatile scaffold that is resistant
to reducing environment and has increased stability in exopeptidase-containing
biological environments. We found that the reduction-resistant disulfide-substituted l-2,3-diaminopropionic acid (Dap) variant possessed near-native
potency. As MASP-2 is involved in the life-threatening thrombosis
in COVID-19 patients, our synthetic, selective MASP-2 inhibitors could
be relevant coronavirus drug candidates.
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variant possessed nearcontaining biological environmentsassociated serine proteaserigidified backbone structurefirst specific mannosecomplement lectin pathwaysystematically modified maspp2 thr residuekey activator proteasesdirected evolution removedinhibitor peptides maspdegree structural plasticity2 inhibitors couldbased masp inhibitorsp2 thrdirected evolutionbased maspstructural plasticityspecific sfmi2like peptidescrystal structureselective maspmasp inhibitionexisting maspstructural stabilitystructural criteriabinding lectinversatile scaffoldtwo terminithreatening thrombosissubstituted lsfmi1 complexreducing environmentphage displaypartially blockednative potencyincreased stabilitydriven increasedisulfide bridgediaminopropionic acidalso aimed2 structures2 inhibition19 patients