The mechanisms of inhibition of two novel scFv antibody inhibitors of the serine protease MT-SP1/matriptase reveal the basis of their potency and specificity. Kinetic experiments characterize the inhibitors as extremely potent inhibitors with K(I) values in the low picomolar range that compete with substrate binding in the S1 site. Alanine scanning of the loops surrounding the protease active site provides a rationale for inhibitor specificity. Each antibody binds to a number of residues flanking the active site, forming a unique three-dimensional binding epitope. Interestingly, one inhibitor binds in the active site cleft in a substrate-like manner, can be processed by MT-SP1 at low pH, and is a standard mechanism inhibitor of the protease. The mechanisms of inhibition provide a rationale for the effectiveness of these inhibitors, and suggest that the development of specific antibody-based inhibitors against individual members of closely related enzyme families is feasible, and an effective way to develop tools to tease apart complex biological processes.
Submitter: Shu-Ching Ou
Submission Date: Feb. 27, 2019, 3:18 p.m.
|Structure ID||Release Date||Resolution||Structure Title|
|1EAW||2001-07-17T00:00:00+0000||2.93||Crystal structure of the MTSP1 (matriptase)-BPTI (aprotinin) complex|
|1EAX||2001-07-17T00:00:00+0000||1.3||Crystal structure of MTSP1 (matriptase)|
|2GV6||2006-05-02T00:00:00+0000||2.1||Crystal Structure of Matriptase with Inhibitor CJ-730|
|2GV7||2006-05-02T00:00:00+0000||2.2||Structure of Matriptase in Complex with Inhibitor CJ-672|
|3BN9||2007-12-13T00:00:00+0000||2.17||Crystal Structure of MT-SP1 in complex with Fab Inhibitor E2|
|3NCL||2010-06-04T00:00:00+0000||1.19||Crystal Structure of MT-SP1 bound to Benzamidine Phosphonate Inhibitor|
|3NPS||2010-06-29T00:00:00+0000||1.5||Crystal structure of membrane-type serine protease 1 (MT-SP1) in complex with the Fab Inhibitor S4|
|3P8F||2010-10-13T00:00:00+0000||2.0||Crystal Structure of MT-SP1 in complex with SFTI-1|
|3P8G||2010-10-13T00:00:00+0000||1.2||Crystal Structure of MT-SP1 in complex with benzamidine|
|3SO3||2011-06-29T00:00:00+0000||2.1||Structures of Fab-Protease Complexes Reveal a Highly Specific Non-Canonical Mechanism of Inhibition.|
|Percent Identity||Matching Chains||Protein||Accession||Entry Name|
|99.6||Suppressor of tumorigenicity 14 protein||Q9Y5Y6||ST14_HUMAN|