MATURATION PATHWAYS FOR ESCHERICHIA-COLI TRANSFER-RNA PRECURSORS - A RANDOM MULTIENZYME PROCESS IN-VIVO

tRNA maturation consists of the specific removal of precursor sequence s from both the 5' and 3' termini of an initial RNA transcript. How th is is accomplished has heretofore not been ascertained in any system. Using Northern analysis of RNA isolated from a variety of RNase-defici ent E. coli strains, we have identified the processing intermediates t hat accumulate in the absence of specific processing nucleases. From t his information we have established the maturation pathways for 12 dif ferent E. coli tRNAs including the specific role of each of the releva nt RNases in the process. The surprising conclusion from this work is that tRNA maturation is a stochastic process that lacks a defined orde r and that can proceed with a variety of alternative 3' processing nuc leases.