A G43 to U43 mutation in E. coli tRNATyrsu3+ which affects processing by RNase P

A novel mutation in the anticodon stem of E. coli tRNA₁^Tyrsu³⁺ (G43 to U43) has been characterized. The gene c⊕ding for the mutant tRNA, carried by phage Ø80DHA61.3 a derivative of Ø80psu₃₊su₀ , produces only 20% of mature suppressor tRNA as compared with Ø80psu₃. Both the mutant tRNA precursor and mature tRNA have an altered conformation. The precursor tR$N+$A coded for by Ø80DHA61.3 is processed by RNase P more slowly than the su^Ø₃. pr$e+$cursor and does not form as stable an enzyme-substrate complex as does su₃, precursor. Ø80DHA61.3 also +contains a large $d¯$eletion which begins in the sp$a¯$cer region between the su, gene and the su₃⁺. gene, extends through the su₀. gene and includes most of the repeated region following the tRNA genes.