Nucleic Acids Research, Vol 25, Issue 21 4194-4200, Copyright © 1997 by Oxford University Press
V Junker, T Teichmann, A Hekele, C Fingerhut and H Beier
In the ciliated protozoa Tetrahymena thermophila introns have been detected
in rRNA and mRNAs until now. We have isolated and sequenced seven tRNATyr
genes from the T.thermophila nuclear genome. All of these genes contain
introns of identical length and sequence. The 11 bp long intervening
sequences are located 1 nt 3' to the anticodon as found in other eukaryotic
nuclear tRNA genes. Tetrahymena tRNATyr genes are efficiently transcribed
in HeLa cell nuclear extract. Moreover, processing and splicing occurred in
HeLa as well as in wheat germ extracts, supporting the notion that
Tetrahymena tRNATyr introns can be classified as authentic tRNA introns. We
have also isolated cytoplasmic tRNATyr from Tetrahymena cells. This tRNATyr
isoacceptor has a QPsiA anticodon and is not a UAG suppressor as shown in
in vitro translation studies. Since UAG and UAA codons are used as
glutamine codons in Tetrahymena macronuclear DNA, the presence of a strong
natural UAG suppressor such as tRNATyr with GPsiA anticodon should cause
misreading of the glutamine as tyrosine codons and the absence of the
latter had thus been predicted. Furthermore we have studied the
organization of tRNATyr genes in the genome of T.thermophila and have found
two types of tRNATyr gene arrangement. A minimum of 12 tRNATyr genes are
present as single copies in genomic DNA HindIII restriction fragments
ranging in size from 0.6 to 7 kb. Additionally one cluster of tRNATyr genes
consisting of six members has been detected in a 2.3 kb HindIII fragment.
ARTICLES
The tRNATyr-isoacceptors and their genes in the ciliate Tetrahymena thermophila: cytoplasmic tRNATyr has a QPsiA anticodon and is coded by multiple intron-containing genes
Institut fur Biochemie, Bayerische Julius-Maximilians-Universitat, Biozentrum, Am Hubland, D-97074 Wurzburg, Germany.
![]()
CiteULike
Connotea
Del.icio.us What's this?
This article has been cited by other articles:
![]() |
H. Beier and M. Grimm Misreading of termination codons in eukaryotes by natural nonsense suppressor tRNAs Nucleic Acids Res., December 1, 2001; 29(23): 4767 - 4782. [Abstract] [Full Text] [PDF] |
||||
