Inhibition of DNA replication in Escherichia coli by cyanide and carbon monoxide.

Ph Weigel,Pt Englund

doi:10.1016/s0021-9258(19)40793-x

Abstract

The inhibition of DNA replication in aerobically growing Escherichia coli by cyanide or carbon monoxide occurs within about 20 s at 15 degrees, as previously reported by Cairns and Denhardt (Cairns, J., and Denhardt, D.T. (1968) J. Mol. Biol. 36, 335-342). This rapid inhibition can be explained by the nearly complete depletion of both intracellular ATP and deoxynucleoside triphosphates which occurs during the time that replication stops. There is probably no direct effect of carbon monoxide on any of the enzymes involved in replication because this reagent has no effect on replication rate or ATP level in anaerobic cells. These cells produce ATP by glycolysis. The inhibition of replication by cyanide, a highly reactive compound, appears to be more complex since anaerobically growing cells can still be completely inhibited, although higher concentrations are required than for aerobically growing cells. The sensitivity of anaerobic cells to cyanide is probably due to the ability of this highly reactive compound to react nonspecifically with many proteins and other molecules.

Highlights

The inhibition of DNA replication in aerobically growing Escherichia coli by cyanide or carbon monoxide Denhardt, occurs within about 20 s at 15”, as previously reported by Cairns and Denhardt
We have confirmed the findings of Cairns and Denhardt [1] that Escherichia coli DNA replication is abruptly halted after addition of KCN(Fig. 2A) or CO (Fig. 3A) to the culture
One possible explanation for this inhibition, which has been previously suggested by others [2], is that ATP may be an essential cofactor for DNA replication and that KCN or CO blocks the production of ATP by inhibiting cytochrome oxidase

Summary

Introduction

The inhibition of DNA replication in aerobically growing Escherichia coli by cyanide or carbon monoxide Denhardt, occurs within about 20 s at 15”, as previously reported by Cairns and Denhardt There is probably no direct effect of carbon monoxide on any of the enzymes involved in replication because this reagent has no effect on replication rate or ATP level in anaerobic cells. The mechanism of this inhibition was not clear, they did provide indirect evidence that the halt in replication was not a consequence of a depletion of the deoxynucleoside triphosphate pool. This evidence was based on the fact that infection of cyanide-inhibited E. coli with bacteriophage. They reported that inhibited after several hours, resuming of KCN [2]. The small amount of DNA synthesized at 37” in the presence of KCN contained a substantial number of single-stranded interruptions, were attributed to the reduced ligase activity [2]

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Conclusion