CONSERVATION OF THE ESCHERICHIA-COLI DNAX PROGRAMMED RIBOSOMAL FRAMESHIFT SIGNAL IN SALMONELLA-TYPHIMURIUM

Escherichia coli DNA polymerase III subunits tau and gamma are produce d from one gene, dnaX, by a programmed ribosomal frameshift which gene rates the C terminal of gamma within the tau reading frame. To help ev aluate the role of the dispensable gamma, the distribution of tau and gamma homologs in several other species and the sequence of the Salmon ella typhimurium dnaX were determined. All four enterobacteria tested produce tau and gamma homologs. S. typhimurium dnaX is 83% identical t o E. coli dnaX, but all four components of the frameshift signal are 1 00% conserved.