Title
Structural basis for the interaction between the IUS-SPRY domain of RanBPM and DDX-4 in germ cell development
Author
Seung Kon Hong, Kook-Han Kim, Eun Joo Song, Eunice EunKyeong Kim
Year
2016
Journal
Journal of Molecular Biology
Abstract
RanBPM and RanBP10 are non-canonical members of the Ran binding protein family that lack the Ran binding domain and do not associate with Ran GTPase in vivo. Rather, they have been shown to be scaffolding proteins that are important for a variety of cellular processes, and both of these proteins contain a SPRY domain, which has been implicated in mediating protein–protein interactions with a variety of targets including the DDX-4 RNA helicase. In this study we have determined the crystal structures of the SPRY domain and approximately 70 upstream residues (IUS motif) of both RanBPM and RanBP10. They are almost identical, comprised of a b-sandwich fold with a set of two helices on each side located at the edge of the sheets. A unique shallow binding surface is formed by highly conserved loops on the surface of the b-sheet with two aspartates on one end, a positive patch on the opposite end, and a tryptophan lining the bottom of the surface. The 20-mer peptide (residues 228–247) of humanDDX-4, an ATP-dependent RNA helicase known to regulate germ cell development, binds to this surface with a KD ~ 13 mM. The crystal structure of the peptide complex along with mutagenesis studies elucidate how RanBPM can recognize its interaction partners to function in gametogenesis.
Instrument
J-1500
Keywords
Circular dichroism, Secondary structure, Biochemistry