Nop53p is a novel nucleolar 60S ribosomal subunit biogenesis protein

• Published in: Biochemical journal 2005-06, Vol.388 (Pt 3), p.819-826
• Main Authors: Sydorskyy, Yaroslav, Dilworth, David J, Halloran, Brendan, Yi, Eugene C, Makhnevych, Taras, Wozniak, Richard W, Aitchison, John D
• Format: Article
• Language: English
• Subjects: Cell Nucleolus - chemistry; Cell Nucleolus - metabolism; Gene Expression Regulation, Fungal; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; Polyribosomes - genetics; Polyribosomes - metabolism; Protein Subunits - chemistry; Protein Subunits - metabolism; Ribosomes - chemistry; Ribosomes - metabolism; RNA, Fungal - genetics; RNA, Fungal - metabolism; RNA, Ribosomal - genetics; RNA, Ribosomal - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj20041297

Ribosome biogenesis in Saccharomyces cerevisiae occurs primarily in a specialized nuclear compartment termed the nucleolus within which the rRNA genes are transcribed by RNA polymerase I into a large 35 S rRNA precursor. The ensuing association/dissociation and catalytic activity of numerous trans-acting protein factors, RNAs and ribosomal proteins ultimately leads to the maturation of the precursor rRNAs into 25, 5.8 and 18 S rRNAs and the formation of mature cytoplasmic 40 and 60 S ribosomal subunits. Although many components involved in ribosome biogenesis have been identified, our understanding of this essential cellular process remains limited. In the present study we demonstrate a crucial role for the previously uncharacterized nucleolar protein Nop53p (Ypl146p) in ribosome biogenesis. Specifically, Nop53p appears to be most important for biogenesis of the 60 S subunit. It physically interacts with rRNA processing factors, notably Cbf5p and Nop2p, and co-fractionates specifically with pre-60 S particles on sucrose gradients. Deletion or mutations within NOP53 cause significant growth defects and display significant 60 S subunit deficiencies, an imbalance in the 40 S:60 S ratio, as revealed by polysome profiling, and defects in progression beyond the 27 S stage of 25 S rRNA maturation during 60 S biogenesis.