View source for 5c67


==Human Mesotrypsin in complex with amyloid precursor protein inhibitor variant APPI-M17G/I18F/F34V==
<StructureSection load='5c67' size='340' side='right'caption='[[5c67]], [[Resolution|resolution]] 1.83&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5c67]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5C67 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5C67 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.83&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=5c67 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5c67 OCA], [https://pdbe.org/5c67 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5c67 RCSB], [https://www.ebi.ac.uk/pdbsum/5c67 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5c67 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/TRY3_HUMAN TRY3_HUMAN] Digestive protease specialized for the degradation of trypsin inhibitors. In the ileum, may be involved in defensin processing, including DEFA5.<ref>PMID:12021776</ref> <ref>PMID:14507909</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Engineered protein therapeutics offer advantages, including strong target affinity, selectivity, and low toxicity, but like natural proteins can be susceptible to proteolytic degradation, thereby limiting their effectiveness. A compelling therapeutic target is mesotrypsin, a protease upregulated with tumor progression, associated with poor prognosis, and implicated in tumor growth and progression of many cancers. However, with its unique capability for cleavage and inactivation of proteinaceous inhibitors, mesotrypsin presents a formidable challenge to the development of biologic inhibitors. We used a powerful yeast display platform for directed evolution, employing a novel multi-modal library screening strategy, to engineer the human amyloid precursor protein Kunitz protease inhibitor domain (APPI) simultaneously for increased proteolytic stability, stronger binding affinity, and improved selectivity for mesotrypsin inhibition. We identified a triple mutant APPIM17G/I18F/F34V, with a mesotrypsin inhibition constant ( Ki ) of 89 pM, as the strongest mesotrypsin inhibitor yet reported; this variant displays 1459-fold improved affinity, up to 350,000-fold greater specificity, and 83-fold improved proteolytic stability vs wild-type APPI. We demonstrated that APPIM17G/I18F/F34V acts as a functional inhibitor in cell-based models of mesotrypsin-dependent prostate cancer cellular invasiveness. Additionally, by solving the crystal structure of the APPIM17G/I18F/F34V/mesotrypsin complex, we obtained new insights into the structural and mechanistic basis for improved binding and proteolytic resistance. Our study identifies a promising mesotrypsin inhibitor as a starting point for development of anticancer protein therapeutics and establishes proof-of-principle for a novel library screening approach that will be widely applicable for simultaneously evolving proteolytic stability in tandem with desired functionality for diverse protein scaffolds.

Combinatorial protein engineering of proteolytically resistant mesotrypsin inhibitors as candidates for cancer therapy.,Cohen I, Kayode O, Hockla A, Sankaran B, Radisky DC, Radisky ES, Papo N Biochem J. 2016 Mar 8. pii: BJ20151410. PMID:26957636<ref>PMID:26957636</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 5c67" style="background-color:#fffaf0;"></div>

==See Also==
*[[Amyloid precursor protein 3D structures|Amyloid precursor protein 3D structures]]
*[[Trypsin 3D structures|Trypsin 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Kayode O]]
[[Category: Radisky ES]]
[[Category: Sankaran B]]