THE AMS-1 AND RNE-3071 TEMPERATURE-SENSITIVE MUTATIONS IN THE AMS GENE ARE IN CLOSE PROXIMITY TO EACH OTHER AND CAUSE SUBSTITUTIONS WITHIN A DOMAIN THAT RESEMBLES A PRODUCT OF THE ESCHERICHIA-COLI MRE LOCUS

Two temperature-sensitive mutations, ams-1 and rne-3071, in the ams (altered mRNA stability) gene have been used extensively to investigate the processing and decay of RNA in Escherichia coli. We have sequenced these temperature-sensitive alleles and found that the mutations are separated by only 6 nucleotides and cause conservative amino acid substitutions next to a possible nucleotide-binding site within the N-terminal domain of the Ams protein. Computer analysis revealed that the region altered by the mutations has extensive sequence similarity to a predicted gene product from the mre (murein pathway cluster e) locus of E. coli, which has been implicated previously in determining bacterial cell shape.