Parvulin (Par14), a peptidyl-prolyl cis-trans isomerase, is a novel rRNA processing factor that evolved in the metazoan lineage.
Although parvulin (Par14/eukaryotic parvulin homolog), a peptidyl-prolyl cis-trans isomerase, is found associated with the preribosomal ribonucleoprotein (pre-rRNP) complexes, its roles in ribosome biogenesis remain undetermined. In this study, we describe a comprehensive proteomics analysis of the Par14-associated pre-rRNP complexes using LC-MS/MS and a knockdown analysis of Par14. Together with our previous results, we finally identified 115 protein components of the complexes, including 39 ribosomal proteins and 54 potential trans-acting factors whose yeast homologs are found in the pre-rRNP complexes formed at various stages of ribosome biogenesis. We give evidence that, although Par14 exists in both the phosphorylated and unphosphorylated forms in the cell, only the latter form is associated with the pre-40 S and pre-60 S ribosomal complexes. We also show that Par14 co-localizes with the nucleolar protein B23 during the interphase and in the spindle apparatus during mitosis and that actinomycin D treatment results in the exclusion of Par14 from the nucleolus. Finally we demonstrate that knockdown of Par14 mRNA decelerates the processing of pre-rRNA to 18 and 28 S rRNAs. We propose that Par14 is a component of the pre-rRNA complexes and functions as an rRNA processing factor in ribosome biogenesis. As the amino acid sequence of Par14 including that in the amino-terminal pre-rRNP binding region is conserved only in metazoan homologs, we suggest that its roles in ribosome biogenesis have evolved in the metazoan lineage.
Department of Biotechnology, United Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan.
Sally
S
Fujiyama-Nakamura
Harunori
H
Yoshikawa
Keiichi
K
Homma
Toshiya
T
Hayano
Teruko
T
Tsujimura-Takahashi
Keiichi
K
Izumikawa
Hideaki
H
Ishikawa
Naoki
N
Miyazawa
Mitsuaki
M
Yanagida
Yutaka
Y
Miura
Takashi
T
Shinkawa
Yoshio
Y
Yamauchi
Toshiaki
T
Isobe
Nobuhiro
N
Takahashi
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002853:Chromatography, Liquid; D019143:Evolution, Molecular; D006801:Humans; D046911:Macromolecular Substances / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D019696:Peptidylprolyl Isomerase / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D040901:Proteomics / Q000379:methods; D034622:RNA Interference; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D053719:Tandem Mass Spectrometry
D046911:Macromolecular Substances; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D012322:RNA Precursors; D012335:RNA, Ribosomal; D011993:Recombinant Fusion Proteins; C000606846:PIN1 protein, human; C000606848:PIN4 protein, human; D019696:Peptidylprolyl Isomerase; C000606850:Pin1 protein, mouse