AtNUFIP, an essential protein for plant development, reveals the impact of snoRNA gene organisation on the assembly of snoRNPs and rRNA methylation in Arabidopsis thaliana.
In all eukaryotes, C/D small nucleolar ribonucleoproteins (C/D snoRNPs) are essential for methylation and processing of ribosomal RNAs. They consist of a box C/D small nucleolar RNA (C/D snoRNA) associated with four highly conserved nucleolar proteins. Recent data in HeLa cells and yeast have revealed that assembly of these snoRNPs is directed by NUFIP protein and other auxiliary factors. Nevertheless, the precise function and biological importance of NUFIP and the other assembly factors remains unknown. In plants, few studies have focused on RNA methylation and snoRNP biogenesis. Here, we identify and characterise the AtNUFIP gene that directs assembly of C/D snoRNP. To elucidate the function of AtNUFIP in planta, we characterized atnufip mutants. These mutants are viable but have severe developmental phenotypes. Northern blot analysis of snoRNA accumulation in atnufip mutants revealed a specific degradation of C/D snoRNAs and this situation is correlated with a reduction in rRNA methylation. Remarkably, the impact of AtNUFIP depends on the structure of snoRNA genes: it is essential for the accumulation of those C/D snoRNAs encoded by polycistronic genes, but not by monocistronic or tsnoRNA genes. We propose that AtNUFIP controls the kinetics of C/D snoRNP assembly on nascent precursors to overcome snoRNA degradation of aberrant RNPs. Finally, we show that AtNUFIP has broader RNP targets, controlling the accumulation of scaRNAs that direct methylation of spliceosomal snRNA in Cajal bodies.
Laboratoire Génome et Développement des Plantes, UMR 5096 Université de Perpignan via Domitia - Centre National de la Recherche Scientifique - Institut de Recherche pour le Développement, Perpignan, France.
Julie
J
Rodor
Edouard
E
Jobet
Jonathan
J
Bizarro
Florence
F
Vignols
Cristel
C
Carles
Takamasa
T
Suzuki
Kenzo
K
Nakamura
Manuel
M
Echeverría
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D005816:Genetic Complementation Test; D008745:Methylation; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009154:Mutation; D010641:Phenotype; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D020871:RNA Stability; D018749:RNA, Plant / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012335:RNA, Ribosomal / Q000737:chemistry*; D020537:RNA, Small Nucleolar / Q000235:genetics* / Q000378:metabolism; D020718:Ribonucleoproteins, Small Nucleolar / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
D029681:Arabidopsis Proteins; D018749:RNA, Plant; D012335:RNA, Ribosomal; D020537:RNA, Small Nucleolar; D020718:Ribonucleoproteins, Small Nucleolar