TY - JOUR
T1 - Saccharomyces cerevisiae Ski7 Is a GTP-Binding Protein Adopting the Characteristic Conformation of Active Translational GTPases
AU - Kowalinski, Eva
AU - Schuller, Anthony
AU - Green, Rachel
AU - Conti, Elena
N1 - Publisher Copyright:
© 2015 The Authors.
PY - 2015/7/9
Y1 - 2015/7/9
N2 - Summary Ski7 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 γ-phosphate of GTP distinguish Ski7 from other trGTPases, suggesting it might function rather as a GTP-binding protein than as a GTP-hydrolyzing enzyme.
AB - Summary Ski7 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 γ-phosphate of GTP distinguish Ski7 from other trGTPases, suggesting it might function rather as a GTP-binding protein than as a GTP-hydrolyzing enzyme.
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U2 - 10.1016/j.str.2015.04.018
DO - 10.1016/j.str.2015.04.018
M3 - Article
C2 - 26051716
AN - SCOPUS:84936847213
SN - 0969-2126
VL - 23
SP - 1336
EP - 1343
JO - Structure
JF - Structure
IS - 7
M1 - 3180
ER -