Regulation of the Escherichia coli S10 ribosomal protein operon by heterologous L4 ribosomal proteins.

We have cloned the L4 ribosomal protein genes from Morganella morganii and Haemophilus influenza. The sequences of these genes were compared with published sequences for Escherichia coli, Yersinia pseudotuberculosis, and Bacillus stearothermophilus. All five of these L4 genes were expressed in E. coli and shown to function as repressors of both transcription and translation of the E. coli S10 operon. Possible implications for regulation of r-protein synthesis in species other E. coli are discussed.