Functional and physical interactions of Krr1p, a Saccharomyces cerevisiae nucleolar protein.

Abstract

The Krr1 protein of Saccharomyces cerevisiae is involved in processing of pre-rRNA and assembly of pre-ribosomal 40S subunits. To further investigate the function of Krr1p we constructed a conditional cold sensitive mutant krr1-21, and isolated seven genes from Schizosaccharomyces pombe whose products suppressed the cold sensitive phenotype of krr1-21 cells. Among the multicopy suppressors we found genes coding for translation elongation factor EF-1alpha, a putative ribose methyltransferase and five genes encoding ribosomal proteins. Using the tandem affinity purification (TAP) method we identified thirteen S. cerevisiae ribosomal proteins interacting with Krr1p. Taken together, these results indicate that Krr1p interacts functionally as well as physically with ribosomal proteins. Northern blot analysis revealed that changes in the level of krr1-21 mRNA were accompanied by similar changes in the level of mRNAs of genes encoding ribosomal proteins. Thus, Krr1p and the genes encoding ribosomal proteins it interacts with seem to be coordinately regulated at the level of transcription.

Crystallization and preliminary crystallographic analysis of the central domain ofDrosophilaDribble, a protein that is essential for ribosome biogenesis

“…Dribble (DBE; Gene ID 33269) is a Drosophila protein that represents a class of evolutionarily conserved proteins in higher eukaryotes (Chan et al, 2001;Xin et al, 2005;Gromadka et al, 2004;Sasaki et al, 2000). This class of proteins is essential for early ribosomal RNA (rRNA) processing (Chan et al, 2001) and ribosome assembly (Sasaki et al, 2000).…”

“…However, the structural identity of the DBE 20-119 fragment is currently unknown. A DBE protein fragment spanning amino-acid residues 16-197 was generated with the aim of studying the protein architecture of this family of proteins and, more importantly, shedding light on their molecular functions (Chan et al, 2001;Xin et al, 2005;Gromadka et al, 2004;Sasaki et al, 2000).…”