The 3' end formation in small RNAs.
Small RNAs are a major class of RNAs along with transfer RNAs, ribosomal RNAs, and messenger RNAs. They vary in size from less than 100 nucleotides to several thousand nucleotides and have been identified and characterized both in prokaryotes and eukaryotes. Small RNAs participate in a variety of cellular functions including regulating RNA synthesis, RNA processing, guiding modifications in RNA, and in transport of proteins. Small RNAs are generated by a series of posttranscriptional processing steps following transcription. While RNA 5' end structure, 5' cap formation, and RNA processing mechanisms have been fairly well characterized, the 3' end processing is poorly understood. Recent data point to an emerging theme in small RNAs metabolism in which the 3' end processing is mediated by the exosome, a large multienzyme complex. In addition to removal of nucleotides by the exosome, there is simultaneous rebuilding of the 3' end of some small RNA by adenylation and/or uridylation. This review presents a picture of both degradative and rebuilding reactions operative on the 3' end of some small RNA molecules in prokaryotes and eukaryotes.
Perumal
Karthika
K
Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030, USA.
Reddy
Ram
R
D000818:Animals; D004926:Escherichia coli / Q000235:genetics; D005057:Eukaryotic Cells / Q000378:metabolism; D005092:Exonucleases / Q000378:metabolism; D006801:Humans; D051379:Mice; D008957:Models, Genetic; D009097:Multienzyme Complexes / Q000378:metabolism; D026723:Polyadenylation; D011387:Prokaryotic Cells / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D026721:RNA 3' End Processing / Q000502:physiology*; D012315:RNA Caps / Q000378:metabolism; D012319:RNA Polymerase II / Q000378:metabolism; D012320:RNA Polymerase III / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012331:RNA, Fungal / Q000378:metabolism; D012340:RNA, Ribosomal, 5.8S / Q000378:metabolism; D012342:RNA, Small Nuclear / Q000737:chemistry*; D020537:RNA, Small Nucleolar / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D017381:Spliceosomes / Q000378:metabolism; D019098:Telomerase / Q000378:metabolism; D016615:Telomere / Q000378:metabolism; D014158:Transcription, Genetic; D014529:Uridine / Q000378:metabolism
D009097:Multienzyme Complexes; D012315:RNA Caps; D012331:RNA, Fungal; D012340:RNA, Ribosomal, 5.8S; D012342:RNA, Small Nuclear; D020537:RNA, Small Nucleolar; D029701:Saccharomyces cerevisiae Proteins; C422952:telomerase RNA; D012313:RNA; D012319:RNA Polymerase II; D019098:Telomerase; D012320:RNA Polymerase III; D005092:Exonucleases; D014529:Uridine