Abstract
Abstract A continuous and unique variation of stable RNA accumulation with pool levels of nucleoside triphosphates was observed when Escherichia coli (K12 Leu-, rel+) cells were entering into phosphate starvation or recovering spontaneously from inhibition by dinitrophenol. Since the rate of RNA accumulation in these experimental systems surpassed all other known systems exhibiting the same pool levels of nucleoside triphosphates, it is suggested that stable RNA synthesis in these systems was subjected to kinetic regulation by substrate concentrations. This kinetic relationship in vivo between RNA synthesis and nucleoside triphosphate substrates was sigmoidal in character and exhibited a higher half-saturation constant than the similar relationship obtained with RNA polymerase in vitro.
Highlights
When the cells were entering into phosphate starvation, as well as in cells recovering spontaneously from high concentrations of dinitophenol, evidence for kinetic regulation was encountered
Starvation--As a culture of E. coli K12 Leu- cells progressively depleted the phosphate in a low phosphate medium, cell growth very gradually slowed down
Simultaneous sampling for ribonucleoside triphosphates yielded the results of Fig. 2
Summary
A continuous and unique variation of stable RNA accumulation with pool levels of nucleoside triphosphates was observed when Escherichia coli (K12 Leu-, rel+) cells were entering into phosphate starvation or recovering spontaneously from inhibition by dinitrophenol. Since the rate of RNA accumulation in these experimental systems surpassed all other known systems exhibiting the same pool levels of nucleoside triphosphates, it is suggested that stable RNA synthesis in these systems was subjected to kinetic regulation by substrate concentrations. 100.~1 cell samples were pipetted into 150 ~1 of 1 s acetic acid, extracted by freeze-thawing (3), and 25 ~1 of each extract were spotted on a polycthylenrimine-impregnated cellulose thin layer sheet. In either instance radioactivity on the dried filter was determined by scintillation counting
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