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4zkd
From Proteopedia
Crystal structure of the S. cerevisiae Ski7 GTPase-like domain, bound to GDP and inorganic phosphate.
Structural highlights
FunctionSKI7_YEAST Represses the expression of non-poly(A) mRNAs like L-A or M viruses and is therefore involved in antiviral system. Mediates interactions via its N-terminus between the exosome and the SKI complex which operate in the 3'-to-5' mRNA-decay pathway. By interacting with NAM7, is also required for nonsense-mediated 3'-to-5' mRNA-decay (NMD). May recognize a stalled 80S ribosome at the 3'-end of a nonstop mRNA which leads to the recruitment of the exosome and SKI complexes to the mRNAs to be degraded.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] Publication Abstract from PubMedSki7 is a cofactor of the cytoplasmic exosome in budding yeast, functioning in both mRNA turnover and non-stop decay (NSD), a surveillance pathway that degrades faulty mRNAs lacking a stop codon. The C-terminal region of Ski7 (Ski7C) shares overall sequence similarity with the translational GTPase (trGTPase) Hbs1, but whether Ski7 has retained the properties of a trGTPase is unclear. Here, we report the high-resolution structures of Ski7C bound to either intact guanosine triphosphate (GTP) or guanosine diphosphate-Pi. The individual domains of Ski7C adopt the conformation characteristic of active trGTPases. Furthermore, the nucleotide-binding site of Ski7C shares similar features compared with active trGTPases, notably the presence of a characteristic monovalent cation. However, a suboptimal polar residue at the putative catalytic site and an unusual polar residue that interacts with the gamma-phosphate of GTP distinguish Ski7 from other trGTPases, suggesting it might function rather as a GTP-binding protein than as a GTP-hydrolyzing enzyme. Saccharomyces cerevisiae Ski7 Is a GTP-Binding Protein Adopting the Characteristic Conformation of Active Translational GTPases.,Kowalinski E, Schuller A, Green R, Conti E Structure. 2015 May 28. pii: S0969-2126(15)00177-X. doi:, 10.1016/j.str.2015.04.018. PMID:26051716[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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