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Clusters of multiple different small nucleolar RNA genes in plants are expressed as and processed from polycistronic pre‐snoRNAs
Author(s) -
Leader David J.,
Clark Gillian P.,
Watters Jenny,
Beven Alison F.,
Shaw Peter J.,
Brown John W.S.
Publication year - 1997
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/16.18.5742
Subject(s) - biology , small nucleolar rna , gene , rna , genetics , gene expression , messenger rna , rna silencing , computational biology , transcriptome , non coding rna , microbiology and biotechnology , rna interference
Small nucleolar RNAs (snoRNAs) are involved in many aspects of rRNA processing and maturation. In animals and yeast, a large number of snoRNAs are encoded within introns of protein‐coding genes. These introns contain only single snoRNA genes and their processing involves exonucleolytic release of the snoRNA from debranched intron lariats. In contrast, some U14 genes in plants are found in small clusters and are expressed polycistronically. An examination of U14 flanking sequences in maize has identified four additional snoRNA genes which are closely linked to the U14 genes. The presence of seven and five snoRNA genes respectively on 2.05 and 0.97 kb maize genomic fragments further emphasizes the novel organization of plant snoRNA genes as clusters of multiple different genes encoding both box C/D and box H/ACA snoRNAs. The plant snoRNA gene clusters are transcribed as a polycistronic pre‐snoRNA transcript from an upstream promoter. The lack of exon sequences between the genes suggests that processing of polycistronic pre‐snoRNAs involves endonucleolytic activity. Consistent with this, U14 snoRNAs can be processed from both non‐intronic and intronic transcripts in tobacco protoplasts such that processing is splicing independent.