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Title | The nonsense-mediated mRNA decay SMG-1 kinase is regulated by large-scale conformational changes controlled by SMG-8. |
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Journal, issue, pages | Genes Dev, Vol. 25, Issue 2, Page 153-164, Year 2011 |
Publish date | Jan 15, 2011 |
Authors | Ernesto Arias-Palomo / Akio Yamashita / Israel S Fernández / Rafael Núñez-Ramírez / Yumi Bamba / Natsuko Izumi / Shigeo Ohno / Oscar Llorca / |
PubMed Abstract | Nonsense-mediated mRNA decay (NMD) is a eukaryotic surveillance pathway that regulates the degradation of mRNAs harboring premature translation termination codons. NMD also influences the expression ...Nonsense-mediated mRNA decay (NMD) is a eukaryotic surveillance pathway that regulates the degradation of mRNAs harboring premature translation termination codons. NMD also influences the expression of many physiological transcripts. SMG-1 is a large kinase essential to NMD that phosphorylates Upf1, which seems to be the definitive signal triggering mRNA decay. However, the regulation of the kinase activity of SMG-1 remains poorly understood. Here, we reveal the three-dimensional architecture of SMG-1 in complex with SMG-8 and SMG-9, and the structural mechanisms regulating SMG-1 kinase. A bent arm comprising a long region of HEAT (huntington, elongation factor 3, a subunit of PP2A and TOR1) repeats at the N terminus of SMG-1 functions as a scaffold for SMG-8 and SMG-9, and projects from the C-terminal core containing the phosphatidylinositol 3-kinase domain. SMG-9 seems to control the activity of SMG-1 indirectly through the recruitment of SMG-8 to the N-terminal HEAT repeat region of SMG-1. Notably, SMG-8 binding to the SMG-1:SMG-9 complex specifically down-regulates the kinase activity of SMG-1 on Upf1 without contacting the catalytic domain. Assembly of the SMG-1:SMG-8:SMG-9 complex induces a significant motion of the HEAT repeats that is signaled to the kinase domain. Thus, large-scale conformational changes induced by SMG-8 after SMG-9-mediated recruitment tune SMG-1 kinase activity to modulate NMD. |
External links | Genes Dev / PubMed:21245168 / PubMed Central |
Methods | EM (single particle) |
Resolution | 24.0 - 30.0 Å |
Structure data | EMDB-1851: EMDB-1852: EMDB-1853: |
Source |
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