Activation of the expression of the microcin C51 operon upon glucose starvation of cells at the exponential growth phase

It was earlier shown that expression of the microcin C51 operon in Escherichia coli cells is activated upon decelerated growth of cells during their transition to the stationary growth phase and depends on the ^S subunit of RNA polymerase. Using a single-copy construct containing the cloned promoter region of the microcin C51 operon and a promoterless lac operon ( P_mcc-lac ), it was shown that the promoter of the microcin operon was also induced by stress caused by the transition of cells at the exponential growth phase into the medium without glucose as a sole carbon source. Activation of P_mcc-lac expression upon severe glucose starvation occurred in rpoS ⁺ and rpoS ^– strains. In cells carrying the rpoD800 mutation that renders the ⁷⁰ subunit of RNA polymerase temperature-sensitive, an activation of P_mcc-lac expression was observed at nonpermissive temperature, in contrast to its complete inhibition in E. coli cells at the phase of delayed growth. Other stressors —nitrogen starvation, high temperatures, osmotic shock, tetracycline and chloramphenicol—did not activate P_mcc-lac expression in cells at the exponential growth phase.Translated from Genetika, Vol. 41, No. 1, 2005, pp. 48–52.Original Russian Text Copyright © 2005 by Veselovskii, Metlitskaya, Lipasova, Bass, Khmel.