Novel inhibition scaffolds targeting human cysteine cathepsins
J. Benýšek1, Z. Kovářová1, M. Mishra1, J. Brynda1,2, M. Buša1, J. Srp1, P. Řezáčová1,2, M. Horn1 and M. Mareš1*
1 Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 16610 Prague, Czech Republic
* mares@uochb.cas.cz
This work is focused on novel structural motives for inhibition of two model human cysteine proteases, namely cathepsin K and cathepsin V. Cathepsin V is overexpressed in breast and colorectal adenomas and adenocarcinomas and is a potential oncology target while cathepsin K is expressed in osteoclasts and has been evaluated as a target for osteoporosis. We demonstrated that cathepsin V is effectively inhibited by PCPI3 (potato cysteine protease inhibitor), a 20 kDa protein isolated from potato tubers which belongs to the plant Kunitz-type inhibitor family. Also, we identified synthetic peptidomimetic compounds containing a nitrile reactive warhead as potent inhibitors of cathepsin K. Both cathepsins and their active-site mutants were produced in the form of recombinant proteins in the P. pastoris expression system and purified. Inhibitor-cathepsin complexes were prepared and subjected to high-throughput crystallization screening. A preliminary crystallographic model of the complex of PCPI3-cathepsin V is presented.