Multiple snoRNA gene clusters from Arabidopsis.
Year: 2001
Type: article
Abstract: Small nucleolar RNAs (snoRNAs) are involved in precursor ribosomal RNA (pre-rRNA) processing and rRNA base modification (2'-O-ribose methylation and pseudouridylation). In all eukaryotes, certain snoRNAs (e.g., U3) are transcribed from classical promoters. In vertebrates, the majority are encoded in introns of protein-coding genes, and are released by exonucleolytic cleavage of linearized intron lariats. In contrast, in maize and yeast, nonintronic snoRNA gene clusters are transcribed as polycistronic pre-snoRNA transcripts from which individual snoRNAs are processed. In this article, 43 clusters of snoRNA genes, an intronic snoRNA, and 10 single genes have been identified by cloning and by computer searches, giving a total of 136 snoRNA gene copies of 71 different snoRNA genes. Of these, 31 represent snoRNA genes novel to plants. A cluster of four U14 snoRNA genes and two clusters containing five different snoRNA genes (U31, snoR4, U33, U51, and snoR5) from Arabidopsis have been isolated and characterized. Of these genes, snoR4 is a novel box C/D snoRNA that has the potential to base pair with the 3' end of 5.8S rRNA and snoR5 is a box H/ACA snoRNA gene. In addition, 42 putative sites of 2'-O-ribose methylation in plant 5.8S, 18S, and 25S rRNAs have been mapped by primer extension analysis, including eight sites novel to plant rRNAs. The results clearly show that, in plants, the most common gene organization is polycistronic and that over a third of predicted and mapped methylation sites are novel to plant rRNAs. The variation in this organization among gene clusters highlights mechanisms of snoRNA evolution.
Source: Europe PMC (PubMed Central)
Authors: J W Brown, G P Clark, D J Leader, C G Simpson, T Lowe
Institution: University of California, Santa Cruz
Language: English
Topic: RNA modifications and cancer
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2162866469