Nature 253, 654 - 656 (20 February 1975); doi:10.1038/253654a0

Regulation of expression of lac operon by a novel function essential for cell growth

MISAO OHKI & SIZUO SATO

Biology Division, National Cancer Center Research Institute, Tsakiji 5-1, Chuo-ku, Tokyo, Japan

THE study of the in vitro transcription of the lac operon using a soluble fraction of bacteria and DNA containing the genes of the lac operon, indicates that gene expression is controlled by both the inducer−operator interaction¹ and the action of cyclic AMP²⁻⁶. We have studied the mutant tsC42 (described previously⁷) and report that the in vivo expression of the lac operon is under the control of a phase-specific protein which is only synthesised or activated 20−30 min before cell division. This protein is essential for both the formation of membrane components and cell growth, as described previously⁷. We describe procedures for the isolation of the mutant and report its specific inability to express the lac operon at the transcriptional level.

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