Shq1 is a conserved protein required for the biogenesis of eukaryotic H/ACA ribonucleoproteins (RNPs), including human telomerase. We report the structure of the Shq1-specific domain alone and in complex with H/ACA RNP proteins Cbf5, Nop10 and Gar1. The Shq1-specific domain adopts a novel helical fold and primarily contacts the PUA domain and the otherwise disordered C-terminal exten-sion (CTE) of Cbf5. The structure shows that dyskeratosis congenita mutations found in the CTE of human Cbf5 likely interfere with Shq1 binding. However, most muta-tions in the PUA domain are not located at the Shq1-binding surface and also have little effect on the yeast Cbf5–Shq1 interaction. Shq1 binds Cbf5 independently of the H/ACA RNP proteins Nop10, Gar1 and Nhp2 and the assembly factor Naf1, but shares an overlapping binding surface with H/ACA RNA. Shq1 point mutations that disrupt Cbf5 interaction suppress yeast growth particu-larly at elevated temperatures. Our results suggest that Shq1 functions as an assembly chaperone that protects the Cbf5 protein complexes from non-specific RNA binding and aggregation before assembly of H/ACA RNA
Is data on this page outdated, violates copyrights or anything else? Report the problem now and we will take corresponding actions after reviewing your request.