The properties of a tRNA-specific adenosine deaminase from Drosophila melanogaster support an evolutionary link between pre-mRNA editing and tRNA modification.
Pre-mRNA editing involving the conversion of adenosine to inosine is mediated by adenosine deaminases that act on RNA (ADAR1 and ADAR2). ADARs contain multiple double-stranded RNA(dsRNA)-binding domains in addition to an adenosine deaminase domain. An adenosine deaminase acting on tRNAs, scTad1p (also known as scADAT1), cloned from Saccharomyces cerevisiae has a deaminase domain related to the ADARs but lacks dsRNA-binding domains. We have identified a gene homologous to scADAT1 in the region of Drosophila melanogaster Adh chromosome II. Recombinant Drosophila ADAT1 (dADAT1) has been expressed in the yeast Pichia pastoris and purified. The enzyme has no activity on dsRNA substrates but is a tRNA deaminase with specificity for adenosine 37 of insect alanine tRNA. dADAT1 shows greater similarity to vertebrate ADARs than to yeast Tad1p, supporting the hypothesis of a common evolutionary origin for ADARs and ADATs. dAdat1 transcripts are maternally supplied in the egg. Zygotic expression is widespread initially and later concentrates in the central nervous system.
Keegan
L P
LP
MRC Human Genetics Unit, Western General Hospital, Edinburgh EH4 2XU, United Kingdom.
Gerber
A P
AP
Brindle
J
J
Leemans
R
R
Gallo
A
A
Keller
W
W
O'Connell
M A
MA
D020121:5' Untranslated Regions / Q000235:genetics; D000243:Adenosine Deaminase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D012831:Bombyx; D003001:Cloning, Molecular; D004331:Drosophila melanogaster / Q000196:embryology / Q000201:enzymology* / Q000235:genetics*; D019143:Evolution, Molecular; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D017393:RNA Editing; D012323:RNA Processing, Post-Transcriptional; D012330:RNA, Double-Stranded / Q000235:genetics / Q000378:metabolism; D012344:RNA, Transfer, Ala / Q000378:metabolism; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014158:Transcription, Genetic; D014714:Vertebrates
D020121:5' Untranslated Regions; D012330:RNA, Double-Stranded; D012344:RNA, Transfer, Ala; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; C567955:ADARB1 protein, human; D000243:Adenosine Deaminase