title: Identification of 20 snoRNA-like RNAs from the primitive eukaryote, Giardia lamblia.
abstract: From a specialized cDNA library of Giardia lamblia, 20 snoRNA-like RNAs, including 16 box C/D sRNAs and four box H/ACA sRNAs, were first identified. The sRNAs were predicted to guide a total of 11 2'-O-methylation and four pseudouridylation sites on the G. lamblia rRNAs, respectively. By using primer extension assay, seven methylation sites were precisely mapped in the G. lamblia 16S rRNA, despite its high GC content. All of the sRNA genes locate on the small intergenic regions of the G. lamblia genome and seem to be independently transcribed from their own promoters. Particularly, a cluster composed of GlsR17 and GlsR18 genes is transcribed as a dicistronic precursor, implying a mechanism of endonuclease cleavage for the maturation of the two sRNAs. The systematic identification of the sRNAs in G. lamblia has provided valuable information about the characteristics of the two major families of small guide RNAs in one of the most primitive eukaryotes and would contribute to the understanding of the evolution of small non-messenger RNA genes from prokaryotes to eukaryotes.
authors.affiliation: Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory for Biocontrol, Zhongshan University, Guangzhou 510275, PR China.
authors.forename: Cheng-Yong
authors.initials: CY
authors.lastname: Yang
authors.forename: Hui
authors.initials: H
authors.lastname: Zhou
authors.forename: Jun
authors.initials: J
authors.lastname: Luo
authors.forename: Liang-Hu
authors.initials: LH
authors.lastname: Qu
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D016829:Giardia lamblia / Q000235:genetics*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D020537:RNA, Small Nucleolar / Q000032:analysis / Q000737:chemistry* / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid
chemical_list: D020537:RNA, Small Nucleolar