EFFECT OF MG2-T5 AND ESCHERICHIA-COLI TRNA(PHE) GENE TRANSCRIPTS( ANDCA2+ ON AMINOACYLATION OF BACTERIOPHAGE)

A recombinant plasmid pT5FO containing the bacteriophage T5 tRNA(Phe) gene flanked with the T7 promoter at one side and the BstN1 site at th e other was designed. Transcription in vitro by T7 RNA polymerase of p T5FO plasmid hydrolyzed with BstN1 produced a transcript of the same n ucleotide sequence as ''mature'' T5 tRNA(Phe) but lacking modified bas es. This transcript was aminoacylated by E. coli phenylalanyl-tRNA syn thetase with a catalytic efficiency (k(cat)/K-M) only 4.3 time lower t han the E. coil tRNA(Phe) transcript. The tRNA(Phe) transcripts of E. coil and phage T5 exhibited different aminoacylation optima depending on Mg2+ ion concentration. Unlike E coli tRNA(Phe), conditions of T5 t RNA(Phe) transcript renaturation were critical for the biologically ac tive conformation. Renaturation in the presence of Ca2+ ions did not r esult in formation ot a functionally active tRNA molecule even after f urther incubation in a solution containing Mg2+ ions.