title: Nop53p is a novel nucleolar 60S ribosomal subunit biogenesis protein.
abstract: 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.
authors.affiliation: Institute for Systems Biology, 1441 N 34th Street, Seattle, WA 98103, USA.
authors.forename: Yaroslav
authors.initials: Y
authors.lastname: Sydorskyy
authors.forename: David J
authors.initials: DJ
authors.lastname: Dilworth
authors.forename: Brendan
authors.initials: B
authors.lastname: Halloran
authors.forename: Eugene C
authors.initials: EC
authors.lastname: Yi
authors.forename: Taras
authors.initials: T
authors.lastname: Makhnevych
authors.forename: Richard W
authors.initials: RW
authors.lastname: Wozniak
authors.forename: John D
authors.initials: JD
authors.lastname: Aitchison
mesh_terms: D002466:Cell Nucleolus / Q000737:chemistry / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011132:Polyribosomes / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C504135:Nop53 protein, S cerevisiae; D009687:Nuclear Proteins; D021122:Protein Subunits; D012331:RNA, Fungal; D012335:RNA, Ribosomal; D029701:Saccharomyces cerevisiae Proteins