Proteomic analysis of human Nop56p-associated pre-ribosomal ribonucleoprotein complexes. Possible link between Nop56p and the nucleolar protein treacle responsible for Treacher Collins syndrome.
Nop56p is a component of the box C/D small nucleolar ribonucleoprotein complexes that direct 2'-O-methylation of pre-rRNA during its maturation. Genetic analyses in yeast have shown that Nop56p plays important roles in the early steps of pre-rRNA processing. However, its precise function remains elusive, especially in higher eukaryotes. Here we describe the proteomic characterization of human Nop56p (hNop56p)-associated pre-ribosomal ribonucleoprotein complexes. Mass spectrometric analysis of purified pre-ribosomal ribonucleoprotein complexes identified 61 ribosomal proteins, 16 trans-acting factors probably involved in ribosome biogenesis, and 29 proteins whose function in ribosome biogenesis is unknown. Identification of pre-rRNA species within hNop56p-associated pre-ribosomal ribonucleoprotein complexes, coupled with the known functions of yeast orthologs of the probable trans-acting factors identified in human, demonstrated that hNop56p functions in the early to middle stages of 60 S subunit synthesis in human cells. Interestingly, the nucleolar phosphoprotein treacle, which is responsible for the craniofacial disorder associated with Treacher Collins syndrome, was found to be a constituent of hNop56p-associated pre-rRNP complexes. The association of hNop56p and treacle within the complexes was independent of rRNA integrity, indicating a direct interaction. In addition, the protein compositions of the treacle-associated and hNop56p-associated pre-ribosomal ribonucleoprotein complexes were very similar, suggesting functional similarities between these two complexes with respect to ribosome biogenesis in human cells.
Hayano
Toshiya
T
Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509.
Yanagida
Mitsuaki
M
Yamauchi
Yoshio
Y
Shinkawa
Takashi
T
Isobe
Toshiaki
T
Takahashi
Nobuhiro
N
D020816:Amino Acid Motifs; D015152:Blotting, Northern; D002460:Cell Line; D002466:Cell Nucleolus / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes; D006801:Humans; D007150:Immunohistochemistry; D008342:Mandibulofacial Dysostosis / Q000378:metabolism; D013058:Mass Spectrometry; D008957:Models, Genetic; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D020543:Proteome / Q000378:metabolism; D012335:RNA, Ribosomal / Q000737:chemistry* / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014162:Transfection
D000939:Epitopes; C486600:NOP56 protein, human; D009687:Nuclear Proteins; D010750:Phosphoproteins; D020543:Proteome; D012335:RNA, Ribosomal; D012261:Ribonucleoproteins; C105442:TCOF1 protein, human; D012260:Ribonucleases