Insertion of IS1 into the rpsE gene for ribosomal protein S5 causes cold-sensitivity in Escherichia coli.

The nucleotide sequence of the rpsE gene for the ribosomal protein S5 of a mutant of E. coli showing cold-sensitive growth revealed the presence of an insertion sequence, IS1, near the 3'-end of the gene. This mutant grows very slowly even at the "permissive temperature" (30 degrees C). At temperatures below 20 degrees C, its growth becomes negligible. It is likely that the presence of IS1 disturbs the continued translation of the polycistronic messenger RNA of the "spc-operon" from the point of IS1 insertion downwards, especially at the unfavorable temperatures.