Crystal structure of the SPRY domain of human SPSB2 in the apo state.
Luo, Y., Li, K., Yang, J., Zhang, D., Zhou, Y., Kuang, Z.(2019) Acta Crystallogr F Struct Biol Commun 75: 412-418
- PubMed: 31204687 
- DOI: https://doi.org/10.1107/S2053230X1900623X
- Primary Citation of Related Structures:  
6JKJ - PubMed Abstract: 
The SPRY domain-containing SOCS box protein 2 (SPSB2) is one of four mammalian SPSB proteins that are characterized by a C-terminal SOCS box and a central SPRY/B30.2 domain. SPSB2 interacts with inducible nitric oxide synthase (iNOS) via the SPRY domain and polyubiquitinates iNOS, resulting in its proteasomal degradation. Inhibitors that can disrupt SPSB2-iNOS interaction and augment NO production may serve as novel anti-infective and anticancer agents. The previously determined murine SPSB2 structure may not reflect the true apo conformation of the iNOS-binding site. Here, the crystal structure of human SPSB2 SPRY domain in the apo state is reported at a resolution of 1.9 Å. Comparison of the apo and ligand-bound structures reveals that the iNOS-binding site is highly preformed and that major conformational changes do not occur upon ligand binding. Moreover, the C-terminal His 6 tag of the recombinant protein binds to a shallow pocket adjacent to the iNOS-binding site on a crystallographically related SPSB2 molecule. These findings may help in structure-based and fragment-based SPSB2 inhibitor design in the future.
Organizational Affiliation: 
Department of Cell Biology and Institute of Biomedicine, College of Life Science and Technology, Jinan University, Guangzhou 510632, People's Republic of China.