Structural and functional insights into the B30.2/SPRY domain

Abstract

The B30.2/SPRY domain is present in B700 eukaryotic (B150 human) proteins, including medically important proteins such as TRIM5a and Pyrin. Nonetheless, the functional role of this modular domain remained unclear. Here, we report the crystal structure of an SPRY-SOCS box family protein GUSTAVUS in complex with Elongins B and C, revealing a highly distorted two-layered b-sandwich core structure of its B30.2/SPRY domain. Ensuing studies identified one end of the b-sandwich as the surface interacting with an RNA helicase VASA with a 40 nM dissociation constant. The sequence variation in TRIM5a responsible for HIV-1 restriction and most of the mutations in Pyrin causing familial Mediterranean fever map on this surface, implicating the corresponding region in many B30.2/SPRY domains as the ligand-binding site. The amino acids lining the binding surface are highly variable among the B30.2/SPRY domains, suggesting that these domains are protein-interacting modules, which recognize a specific individual partner protein rather than a consensus sequence motif.

The B30.2 domain of pyrin, the familial Mediterranean fever protein, interacts directly with caspase-1 to modulate IL-1β production

“…6); the side-chain atoms of both residues were within 5 Å of atoms of the receptor. This finding is in agreement with the potential B30.2͞SPRY domain-binding interface identified by mutational analysis (10,12). Examination of the orientation of caspase-1 in this model revealed also that both the p10 and p20 subunits of caspase-1 contribute to the interaction with pyrin, corroborating our experimental data (Fig.…”

“…The structure of caspase-1 is well defined (27,28), and models for the structure of the pyrin B30.2 domain have been recently reported (10)(11)(12). We thought to produce a model for the interaction of these structures computationally and analyze this interaction with regard to our experimental data.…”

“…This article demonstrates that pyrin also modulates caspase-1 activation through a second interaction involving the binding of its C-terminal B30.2 domain to the catalytic domains of caspase-1. The B30.2 domain is found in Ͼ500 different proteins of various functions and is thought to mediate proteinprotein interactions (9)(10)(11)(12). The B30.2 domain, in turn, comprises an Ϸ139-aa C-terminal SPRY segment (named after the dualpurpose splA kinase and the ryanodine receptor) and an Ϸ61-aa N-terminal PRY subdomain.…”

“…Recently, the structure of the SPRY domain of SSB-2 was determined by NMR (10), and the structures of a second SPRY domain and a B30.2 domain were solved by crystallography (11,12). All three analyses indicated a ␤-sandwich structure formed by antiparallel ␤-sheets in the SPRY domain and showed that the residues equivalent to the M694V and M680I mutations in the pyrin B30.2 domain fall in distinct loops comprising a common binding surface.…”

“…B30.2 domains in other proteins are thought to mediate proteinprotein interactions (9)(10)(11)(12), although the precise role of pyrin's B30.2 domain is unknown. In contrast, the Ϸ90 aa at the N terminus of pyrin define a motif, variously called the PYRIN domain (13,14), PYD (15), PAAD (16), or DAPIN (17), that is rarely mutated in FMF, and assumes a six ␣-helical death-fold structure similar to death domains, death effector domains, and caspase recruitment domains (CARDs).…”