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Isolation and Characterization of Conditional-Lethal Rho Mutants of Escherichia coli
Hidetoshi Inoko, Katsuya Shigesada and Mutsuo Imai
Proceedings of the National Academy of Sciences of the United States of America
Vol. 74, No. 3 (Mar., 1977), pp. 1162-1166
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/66362
Page Count: 5
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Temperature-sensitive nitA (rho) mutants of E. coli were isolated; one of them was characterized as an amber mutant. These strains show the Nit phenotype (transcription of phage λ DNA independent of the N gene) at low temperatures and are inviable at high temperatures. The mutated sites appear to be between cya and metE on the chromosome. Temperature-sensitive nitA bacteria not only permit leftward transcription of the λ genome at a high rate in the absence of the λ N protein, but also allow λ growth at low temperatures. At high temperatures, phages λ and T4 are incapable of normal development in these cells, while growth of T7 is not affected. The production of thermally unstable rho by the nitA temperature-sensitive mutant suggests that nitA is the structural gene for rho.
Proceedings of the National Academy of Sciences of the United States of America © 1977 National Academy of Sciences