3L3T

Human mesotrypsin complexed with amyloid precursor protein inhibitor variant (APPIR15K)

Summary for 3L3T

• Entry DOI: 10.2210/pdb3l3t/pdb
• Related: 1ZJD 2R9P
• Descriptor: PRSS3 protein, Protein APP, FORMIC ACID, ... (5 entities in total)
• Functional Keywords: human mesotrypsin, canonical inhibitor, alzheimer's amyloid precursor protein inhibitor, appi, appi-r15k, hydrolase-cell adhesion complex, hydrolase/cell adhesion
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 8
• Total formula weight: 122784.33

Authors

Salameh, M.A.,Soares, A.S.,Radisky, E.S. (deposition date: 2009-12-17, release date: 2010-09-22, Last modification date: 2024-10-30)

Primary citation

Salameh, M.A.,Soares, A.S.,Navaneetham, D.,Sinha, D.,Walsh, P.N.,Radisky, E.S.
Determinants of affinity and proteolytic stability in interactions of Kunitz family protease inhibitors with mesotrypsin.
J.Biol.Chem., 285:36884-36896, 2010

PubMed Abstract: An important functional property of protein protease inhibitors is their stability to proteolysis. Mesotrypsin is a human trypsin that has been implicated in the proteolytic inactivation of several protein protease inhibitors. We have found that bovine pancreatic trypsin inhibitor (BPTI), a Kunitz protease inhibitor, inhibits mesotrypsin very weakly and is slowly proteolyzed, whereas, despite close sequence and structural homology, the Kunitz protease inhibitor domain of the amyloid precursor protein (APPI) binds to mesotrypsin 100 times more tightly and is cleaved 300 times more rapidly. To define features responsible for these differences, we have assessed the binding and cleavage by mesotrypsin of APPI and BPTI reciprocally mutated at two nonidentical residues that make direct contact with the enzyme. We find that Arg at P(1) (versus Lys) favors both tighter binding and more rapid cleavage, whereas Met (versus Arg) at P'(2) favors tighter binding but has minimal effect on cleavage. Surprisingly, we find that the APPI scaffold greatly enhances proteolytic cleavage rates, independently of the binding loop. We draw thermodynamic additivity cycles analyzing the interdependence of P(1) and P'(2) substitutions and scaffold differences, finding multiple instances in which the contributions of these features are nonadditive. We also report the crystal structure of the mesotrypsin·APPI complex, in which we find that the binding loop of APPI displays evidence of increased mobility compared with BPTI. Our data suggest that the enhanced vulnerability of APPI to mesotrypsin cleavage may derive from sequence differences in the scaffold that propagate increased flexibility and mobility to the binding loop.

PubMed: 20861008
DOI: 10.1074/jbc.M110.171348

Experimental method

X-RAY DIFFRACTION (2.378 Å)