Expression studies on clustered trypanosomatid box C/D small nucleolar RNAs.
We analyzed three chromosomal loci of the trypanosomatid Leptomonas collosoma encoding box C/D small nucleolar RNAs (snoRNAs). All the snoRNAs that were analyzed here carry two sequences complementary to rRNA target sites and obey the +5 rule for guide methylation. Studies on transgenic parasites carrying the snoRNA-2 gene in the episomal expression vector (pX-neo) indicated that no promoter activity was found immediately adjacent to this gene. Deleting the flanking sequences of snoRNA-2 affected the expression; in the absence of the 3'-flanking (but not 5'-flanking) sequence, the expression was almost completely abolished. The snoRNA genes are transcribed as polycistronic RNA. All snoRNAs can be folded into a common stem-loop structure, which may play a role in processing the polycistronic transcript. snoRNA B2, a member of a snoRNA cluster, was expressed when cloned into the episomal vector, suggesting that each gene within a cluster is individually processed. Studies with permeable cells indicated that snoRNA gene transcription was relatively sensitive to alpha-amanitin, thus supporting transcription by RNA polymerase II. We propose that snoRNA gene expression, similar to protein-coding genes in this family, is regulated at the processing level.
Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
Y
Y
Xu
L
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Liu
C
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Lopez-Estraño
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Michaeli
D000546:Amanitins / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D019175:DNA Methylation; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D017353:Gene Deletion; D005822:Genetic Vectors; D008957:Models, Genetic; D008969:Molecular Sequence Data; D005810:Multigene Family; D009690:Nucleic Acid Conformation; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D009841:Oligonucleotides / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012319:RNA Polymerase II / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020537:RNA, Small Nucleolar / Q000648:ultrastructure*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012266:Ribose / Q000378:metabolism; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic; D014345:Trypanosoma / Q000235:genetics* / Q000378:metabolism*
D000546:Amanitins; D019384:Nucleic Acid Synthesis Inhibitors; D009841:Oligonucleotides; D012333:RNA, Messenger; D020537:RNA, Small Nucleolar; D012266:Ribose; D012319:RNA Polymerase II; D012321:DNA-Directed RNA Polymerases