Mechanism of growth delay induced in Escherichia coli by near ultraviolet radiation.

Journal Article · Thu Jan 01 04:00:00 EST 1976 · Proceedings of the National Academy of Sciences of the United States of America

DOI:https://doi.org/10.1073/pnas.73.1.59· OSTI ID:4087117

Ramabhadran, T. V.; Jagger, J.

Continuously growing cultures of E. coli B/r were irradiated with a fluence of broad-band near-ultraviolet radiation (315 to 405 nm) sufficient to cause extensive growth delay and complete cessation of net RNA synthesis. Chloramphenicol treatment was found to stimulate resumption of RNA synthesis, similar to that observed with chloramphenicol treatment after amino-acid starvation. E. coli strains in which amino-acid starvation does not result in cessation of RNA synthesis (''relaxed'' or rel$sup -$ strains) show no cessation of growth and only a slight effect on the rate of growth or of RNA synthesis. These findings show that such near-uv fluences do not inactivate the RNA synthetic machinery but affect the regulation of RNA synthesis, in a manner similar to that produced by amino-acid starvation. Such regulation is believed to be mediated through alterations in concentration of guanosine tetraphosphate (ppGpp), and our estimations of ppGpp after near-uv irradiation are consistent with such an interpretation. These data, combined with earlier published data, strongly suggest that the mechanism of near-uv-induced growth delay in E. coli involves partial inactivation of certain tRNA species, which is interpreted by the cell in a manner similar to that of amino-acid starvation, causing a rise in ppGpp levels, a shut-off of net RNA synthesis, and the induction of a growth delay. (auth)

• Research Organization: Univ. of Texas, Dallas
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-020486
• OSTI ID: 4087117
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 1 Vol. 73; ISSN 0027-8424
• Publisher: National Academy of Sciences, Washington, DC (United States)
• Country of Publication: United States
• Language: English

Related Subjects

*CHLORAMPHENICOL-- RADIOSENSITIVITY EFFECTS
*ESCHERICHIA COLI-- GROWTH
*RNA-- BIOSYNTHESIS
560131* --Biomedical Sciences
Applied Studies--Radiation Effects--Radiation Effects on Microorganisms--Basic Studies
AMINO ACIDS
N48210* --Life Sciences--Radiation Effects on Cells-- External Source
ULTRAVIOLET RADIATION