Crystal Structure of SPSB2 in Complex With a Rational Designed RGD-containing Cyclic Peptide Inhibitor of SPSB2-iNOS Interaction

Tingting You, Yuhui Wang, Kefa Li, Danting Zhang, Huan Wei, Yanhong Luo, Hua Li, Yongzhi Lu, Xunchen Su, Zhihe Kuang

Biochem Biophys Res Commun. 2017 Jul 29;489(3):346-352.

PMID: 28549582

Abstract:

SPRY domain-containing SOCS box protein 2 (SPSB2) is a negative regulator of inducible nitric oxide synthase (iNOS) that modulates the lifetime of iNOS and thus the levels of nitric oxide (NO) production. Inhibitors that can disrupt the endogenous SPSB2-iNOS interaction and augment NO production have potential as novel antimicrobial and anticancer drugs. In this study, we have designed a cyclic peptide (cR8), containing an RGD motif and the SPSB2 binding motif (DINNNV). ITC and chemical shift perturbation showed that cR8 binds to the iNOS binding site on SPSB2 with a Kd of 671 nM, and saturation transfer difference NMR showed that cR8 binds to αvβ3 integrin-expressing cells. Moreover, we determined the crystal structure of SPSB2 in complex with cR8, at a resolution of 1.34 Å. cR8 forms extensive hydrogen bonding with SPSB2 residues, but loss of an intramolecular hydrogen bond that is present in SPSB2-bound iNOS peptide may destabilize the bound conformation of cR8 and lead to a gentle reduction in SPSB2 binding affinity. These results serve as a useful basis for designing site-directed SPSB2 inhibitors in the future.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP294646778	CR8		294646-77-8	Price