Design and characterization of Escherichia coli mutants devoid of Ap4N-hydrolase activity.
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| Abstract |
Escherichia coli strains with abnormally high concentrations of bis(5'-nucleosidyl)-tetraphosphates (Ap4N) were constructed by disrupting the apaH gene that encodes Ap4N-hydrolase. Variation deletions and insertions were also introduced in apaG and ksgA, two other cistrons of the ksgA apaGH operon. In all strains studied, a correlation was found between the residual Ap4N-hydrolase activity and the intracellular Ap4N concentration. In cells that do not express apaH at all, the Ap4N concentration was about 100-fold higher than in the parental strain. Such a high Ap4N level did not modify the bacterial growth rate in rich or minimal medium. However, while, as expected, the ksgA- and apaG- ksgA- strains stopped growing in the presence of this antibiotic at 600 micrograms/ml. The were not sensitive to kasugamycin, the apaH- apaG- ksgA- strain filamented and stopped growing in the presence of this antibiotic at 600 micrograms/ml. The growth inhibition was abolished upon complementation with a plasmid carrying an intact apaH gene. Trans addition of extra copies of the heat-shock gene dnaK also prevented the kasugamycin-induced filamentation of apaH- apaG- ksgA- strains. This result is discussed in relation to the possible involvement of Ap4N in cellular adaptation following a stress.
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| Authors | F Lévĕque, S Blanchin-Roland, G Fayat, P Plateau, S Blanquet |
| Journal | Journal of molecular biology (J Mol Biol) Vol. 212 Issue 2 Pg. 319-29 (Mar 20 1990) ISSN: 0022-2836 [Print] Netherlands |
| PMID | 2157025 (Publication Type: Journal Article) |
| Chemical References |
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