Bacterial DNA supercoiling and [ATP]/[ADP] ratio: changes associated with salt shock. |
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Authors: | L S Hsieh J Rouviere-Yaniv and K Drlica |
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Institution: | Public Health Research Institute, New York, New York 10016. |
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Abstract: | When Escherichia coli K-12 was shifted from a medium lacking salt to one containing 0.5 M NaCl, both the ATP]/ADP] ratio and negative supercoiling of plasmid DNA increased within a few minutes. After about 10 min both declined, eventually reaching a level slightly above that observed with cells growing exponentially in the absence of salt. Since in vitro the ATP]/ADP] ratio influences the level of supercoiling generated by gyrase (H. Westerhoff, M. O'Dea, A. Maxwell, and M. Gellert, Cell Biophys. 12:157-181, 1988), the physiological response of supercoiling to salt shock is most easily explained by the sensitivity of gyrase to changes in the intracellular ATP]/ADP] ratio. This raises the possibility that the ATP]/ADP] ratio is an important factor in the control of supercoiling. |
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