tadA, an essential tRNA-specific adenosine deaminase from Escherichia coli

AUTOR(ES)

Wolf, Jeannette

FONTE

Oxford University Press

RESUMO

We report the characterization of tadA, the first prokaryotic RNA editing enzyme to be identified. Escherichia coli tadA displays sequence similarity to the yeast tRNA deaminase subunit Tad2p. Recom binant tadA protein forms homodimers and is sufficient for site-specific inosine formation at the wobble position (position 34) of tRNAArg2, the only tRNA having this modification in prokaryotes. With the exception of yeast tRNAArg, no other eukaryotic tRNA substrates were found to be modified by tadA. How ever, an artificial yeast tRNAAsp, which carries the anticodon loop of yeast tRNAArg, is bound and modified by tadA. Moreover, a tRNAArg2 minisubstrate containing the anticodon stem and loop is sufficient for specific deamination by tadA. We show that nucleotides at positions 33–36 are sufficient for inosine formation in mutant Arg2 minisubstrates. The anticodon is thus a major determinant for tadA substrate specificity. Finally, we show that tadA is an essential gene in E.coli, underscoring the critical function of inosine at the wobble position in prokaryotes.

Documentos Relacionados

• The Properties of a tRNA-Specific Adenosine Deaminase from Drosophila melanogaster Support an Evolutionary Link between Pre-mRNA Editing and tRNA Modification
• Identification and characterization of a human tRNA-specific adenosine deaminase related to the ADAR family of pre-mRNA editing enzymes
• Excision of large DNA regions termed pathogenicity islands from tRNA-specific loci in the chromosome of an Escherichia coli wild-type pathogen.
• Selenocysteine tRNA-specific elongation factor SelB is a structural chimaera of elongation and initiation factors
• Structural and mutational studies of the recognition of the arginine tRNA-specific major identity element, A20, by arginyl-tRNA synthetase