Preferential charging of tRNA-Met-f in Escherichia coli K12.

The charging of tRNA-Met-f and tRNA-Met-m in vivo and in vitro and initiation of polysomes during methionine limitation were studied in two strains of Escherichia coli K12. In the wild-type strain the distribution of polysomes as well as the kinetic parameters of methionyl-tRNA synthetase indicate preferential acylation of tRNA-Met-f. This preferential charging of tRNAM-et-f does not take place in a mutant strain which is also defective in initiation of polysomes during methionine limitation.