2mr9
From Proteopedia
NMR structure of UBA domain of DNA-damage-inducible 1 protein (Ddi1)
Structural highlights
FunctionDDI1_YEAST Acts as a linker between the 19S proteasome and polyubiquitinated proteins like the HO endonuclease and UFO1 via UBA domain interactions with ubiquitin for their subsequent degradation. Required for S-phase checkpoint control. Appears to act as negative regulator of constitutive exocytosis. May act at the level of secretory vesicle docking and fusion as a competitive inhibitor of SNARE assembly.[1] [2] [3] [4] [5] [6] [7] Publication Abstract from PubMedDdi1 belongs to a family of shuttle proteins targeting polyubiquitinated substrates for proteasomal degradation. Unlike the other proteasomal shuttles, Rad23 and Dsk2, Ddi1 remains an enigma: its function is not fully understood and structural properties are poorly characterized. We determined the structure and binding properties of the ubiquitin-like (UBL) and ubiquitin-associated (UBA) domains of Ddi1 from Saccharomyces cerevisiae. We found that while Ddi1UBA forms a characteristic UBA:ubiquitin complex, Ddi1UBL has entirely uncharacteristic binding preferences. Despite having a ubiquitin-like fold, Ddi1UBL does not interact with typical UBL receptors but unexpectedly binds ubiquitin, forming a unique interface mediated by hydrophobic contacts and by salt bridges between oppositely charged residues of Ddi1UBL and ubiquitin. In stark contrast to ubiquitin and other UBLs, the beta-sheet surface of Ddi1UBL is negatively charged and therefore is recognized in a completely different way. The dual functionality of Ddi1UBL, capable of binding both ubiquitin and proteasome, suggests an intriguing mechanism for Ddi1 as a proteasomal shuttle. DNA-Damage-Inducible 1 Protein (Ddi1) Contains an Uncharacteristic Ubiquitin-like Domain that Binds Ubiquitin.,Nowicka U, Zhang D, Walker O, Krutauz D, Castaneda CA, Chaturvedi A, Chen TY, Reis N, Glickman MH, Fushman D Structure. 2015 Mar 3;23(3):542-57. doi: 10.1016/j.str.2015.01.010. Epub 2015 Feb, 19. PMID:25703377[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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