NOF1 Encodes an Arabidopsis Protein Involved in the Control of rRNA Expression

Abstract

The control of ribosomal RNA biogenesis is essential for the regulation of protein synthesis in eukaryotic cells. Here, we report the characterization of NOF1 that encodes a putative nucleolar protein involved in the control of rRNA expression in Arabidopsis. The gene has been isolated by T-DNA tagging and its function verified by the characterization of a second allele and genetic complementation of the mutants. The nof1 mutants are affected in female gametogenesis and embryo development. This result is consistent with the detection of NOF1 mRNA in all tissues throughout plant life's cycle, and preferentially in differentiating cells. Interestingly, the closely related proteins from zebra fish and yeast are also necessary for cell division and differentiation. We showed that the nof1-1 mutant displays higher rRNA expression and hypomethylation of rRNA promoter. Taken together, the results presented here demonstrated that NOF1 is an Arabidopsis gene involved in the control of rRNA expression, and suggested that it encodes a putative nucleolar protein, the function of which may be conserved in eukaryotes.

Ribosomal Protein RPL27a Promotes Female Gametophyte Development in a Dose-Dependent Manner

“…By comparison, ribosome biogenesis mutants swa1, swa2, swa3/atrh36, and nof1 that are female gametophyte lethal initiate megagametogenesis but do not complete mitotic cell divisions (Shi et al, 2005;Li et al, 2009;Harscoët et al, 2010;Huang et al, 2010;Liu et al, 2010). In swa1, defective embryo sacs are asynchronous with development arrested at the functional megaspore stage or at two, four, or eight nuclei stages of development.…”

“…SLOW WALKER1 (SWA1), SWA3/Arabidopsis thaliana RNA HELICASE36 (AtRH36), and NUCLEOLAR FACTOR1 (NOF1) encode nucleolar-localized proteins required for processing 18S pre-rRNA (Shi et al, 2005;Harscoët et al, 2010;Huang et al, 2010;Liu et al, 2010). Mutations in other genes encoding proteins predicted to be involved in pre-rRNA processing and ribosome maturation or in export of preribosomes from the nucleus to the cytoplasm also reduce female fertility (Li et al, 2009(Li et al, , 2010Chantha et al, 2010;Wang et al, 2012;Missbach et al, 2013).…”

Arabidopsis MAS2, an Essential Gene That Encodes a Homolog of Animal NF-κ B Activating Protein, Is Involved in 45S Ribosomal DNA Silencing

“…To determine the DNA methylation status of the 59ETS region in amiR-MAS2.1 plants, we digested genomic DNA with the methylation-sensitive endonuclease HpaII. Digested or nondigested DNA was used as template for quantitative PCR amplification using primers that flank the restriction sites (p2f and p2r) and hybridize downstream of the transcription initiation site ( Figure 9A; Harscoët et al, 2010). We found that the ratio between digested and nondigested DNA was strongly reduced in amiR-MAS2.1/amiR-MAS2.1 plants compared with Col-0 (Figure 9E), indicating that the promoter was hypomethylated in amiR-MAS2.1/amiR-MAS2.1 plants, as occurred in the nuc-L1 and hda6 mutants.…”

“…Cleavage by HpaII of the 59-CCGG-39 tetranucleotide is blocked by the presence of 5-MeC at this site (59-C me CGG-39). Digested and nondigested DNA was used as template for quantitative PCR amplifications using the p2f and p2r primers, which flank the restriction sites (Supplemental Table 2; Harscoët et al, 2010). The 25S rRNA gene was amplified with the 25SrRNA_F/R primer set and used as an endogenous control for quantitative PCR experiments.…”

Suppression of Dwarf and irregular xylem Phenotypes Generates Low-Acetylated Biomass Lines in Arabidopsis

“…A 2-kb sequence upstream from the KAK gene transcription starting site was amplified from wild-type genomic DNA using attB-flanked primers for subsequent Gateway cloning (primers are listed in Supplemental Table S1). The PCR product was first cloned into a pDONR207 vector (Invitrogen; http:// www.lifetechnologies.com) with a BP reaction and transferred using an LR reaction into pBI101-R2R3-GUS, a Gateway-compatible binary vector derived from pBI101 (Harscoët et al, 2010), to generate a transcriptional fusion between the KAK promoter (KAK pro ) and the GUS reporter gene. The KAK pro :GUS construct was introduced into wild-type plants by Agrobacterium tumefaciensmediated transformation as described previously (Bechtold and Pelletier, 1998).…”