RECOGNITION OF TRANSFER-RNA BY THE ENZYME ATP/CTP-TRANSFER RNA NUCLEOTIDYLTRANSFERASE - INTERFERENCE BY NUCLEOTIDES MODIFIED WITH DIETHYL PYROCARBONATE OR HYDRAZINE

  • 5 March 1989
    • journal article
    • research article
    • Vol. 264  (7) , 3799-3805
Abstract
Treatment of tRNA with diethyl pyrocarbonate or hydrazine prior to incubation with the enzyme ATP/CTP:tRNA nucleotidyltransferase and [.alpha.-32P]ATP results in exclusion of modified bases from labeled molecules. Purines modified with diethyl pyrocarbonate, which interfere with enzyme recognition, cluster at the corner of the tRNA molecule, where the D- and .PSI.-loops are juxtaposed in all 15 tRNAs used in this study. When the enzyme is isolated from Escherichia coli, few other sites of interference are evident near the 3''-end; when the homologous enzyme from yeast is used, more exclusions are apparent near the 3''-end. Modification of uridines with hydrazine has no effect on interaction with the enzyme, except for one uridine near the 3''-end of tRNAGly. Interference of enzyme activity by modified bases can be overcome by longer incubation times or increased concentrations of enzyme.