The rat mitochondrial Ori L encodes a novel small RNA resembling an ancestral tRNA.
The RNA minihelix, a proposed tRNA precursor, exhibits tRNA-like properties. Sequence-specific RNA minihelices can inhibit cell growth probably due to their binding to the cognate tRNA and naturally occurring non-tRNA substrates for aminoacylation may serve a similar purpose. Thus far, no natural RNA minihelices have been found. In the present study, we found a novel small RNA of 32 nucleotides, which is expressed abundantly in all rat tissues tested. Distinct from all of known endogenous small RNAs, this small RNA (temporarily named as tpl-sRNA) can form an RNA minihelix containing a stem-loop domain followed by ACCA. tpl-sRNA is encoded by the light-strand replication origin (Ori L) of the rat mitochondrial genome, and the 3'-terminal CCA of tpl-sRNA is post-transcriptionally added. Moreover, tpl-sRNA is chargeable in vivo. Our study demonstrates for the first time an endogenous small RNA that resembles an ancestral tRNA and exhibits some tRNA-like properties in mammals.
Yu
Chun-Hong
CH
Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory for Biocontrol, Zhongshan University, Guangzhou 510275, PR China.
Liao
Jian-You
JY
Zhou
Hui
H
Qu
Liang-Hu
LH
D049148:Aminoacylation; D000818:Animals; D001483:Base Sequence; D019143:Evolution, Molecular; D005815:Genetic Code; D054629:Genome, Mitochondrial; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012343:RNA, Transfer / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D022661:RNA, Untranslated / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D051381:Rats; D018741:Replication Origin / Q000235:genetics*
D022661:RNA, Untranslated; D012343:RNA, Transfer