Summary
Three amber mutants of Escherichia coli, dnaG9, dnaG24 and dnaG26, affected in the structural gene (dnaG) for “primase” have been isolated from a parental strain carrying a temperature-sensitive amber suppressor (supF-Ts6). These mutants grow at 30° C but not at 42° C since primase is essential for growth and is synthesized only at low temperatures. Chimeric plasmids carrying dnaG + but no other chromosomal genes of E. coli complemented the amber mutations, and the plasmid carrying a part of dnaG lost the complementing activity. Beside, plasmids carrying a dnaG amber mutation complemented a temperature-sensitive dnaG mutation only in the presence of amber suppressor. One of the amber mutation, dnaG24 which maps proximal to the NH2-terminus of the dnaG gene, exerted a polar effect on the synthesis of RNA polymerase σ factor in E. coli.
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Communicated by E. Bautz
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Nakamura, Y. Amber dnaG mutation exerting a polar effect on the synthesis of RNA polymerase sigma factor in Escherichia coli . Mol Gen Genet 196, 179–182 (1984). https://doi.org/10.1007/BF00334114
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DOI: https://doi.org/10.1007/BF00334114