Mutations in the rpIJ leader of Escherichia coli that abolish feedback regulation.

We have isolated mutants that fail to exhibit biosynthetic feedback regulation of a rpIJ-lacZ fusion. Analysis of these mutants and of others that were isolated earlier indicates that crucial sequences for both translational feedback regulation and efficient translation lie closely intermingled in the central region of the rpIJ mRNA leader 70-195 bases upstream from the translation start of rpIJ. We suggest that our point mutations define a region of the rpIJ leader mRNA to which L10 binds in effecting autogenous translational regulation.