Godin KS, et al. (2009) The box H/ACA snoRNP assembly factor Shq1p is a chaperone protein homologous to Hsp90 cochaperones that binds to the Cbf5p enzyme. J Mol Biol 390(2):231-44
Abstract: Box H/ACA small nucleolar ribonucleoproteins (snoRNPs) are responsible for the formation of pseudouridine in a variety of RNAs, and are essential for ribosome biogenesis, modification of spliceosomal RNAs and telomerase stability. The mature snoRNP has been reconstituted in vitro and is composed of a single RNA and four proteins. However, snoRNP biogenesis in vivo requires multiple factors to coordinate a complex and poorly understood assembly and maturation process. Among the factors required for snoRNP biogenesis in yeast is Shq1p, an essential protein necessary for the snoRNA stable expression. We have found that Shq1p consists of two independent domains that contain Casein Kinase 1 phosphorylation sites. We also demonstrate that Shq1p binds the pseudourydilating enzyme Cbf5p through the C-terminal domain in synergy with the N-terminal domain. The NMR solution structure of the N-terminal domain has striking homology to the 'Chord and Sgt1' (CS) domain of known Hsp90 co-chaperones, yet Shq1p does not interact with the yeast Hsp90 homologue in vitro. Surprisingly, Shq1p has stand-alone chaperone activity in vitro. This activity is harbored by the C-terminal domain but it is increased by the presence of the N-terminal domain. These results provide the first evidence of a specific biochemical activity for Shq1p and a direct link to the H/ACA snoRNP.
|Status: Published||Type: Journal Article||PubMed ID: 19426738|
Topics addressed in this paper
Number of different genes curated to this paper: 5
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|Fungal Related Genes/Proteins|
|Non-Fungal Related Genes/Proteins|
|Protein Sequence Features|
|Protein/Nucleic Acid Structure|