Isolation and characterisation of E. coli B/R mutant having a hyper-HCR phenotype

Journal Article · Mon Jan 01 04:00:00 EST 1973 · Stud. Biophys., v. 36-37, pp. 325-342

OSTI ID:4437557

Collis, T; Clarke, C

From international conference on the bases of the biological effects of ultraviolet radiation; Brno, Czechoslovakla (2 Oct 1972). Following nitrosoguanidine mutagenesis approximately 2000 colonies of Escherichla coli B/r were screened by a spot-testing technique for ability to reactivate uv-irradiated phage T/sub 3/ to an enhanced extent. One such hyper-reactivating (HRH) mutant was isolated. This isolate has the same growth rate and uv-sensitivity as the parental E. coli B/r strain. However, it shows a greatly enhanced ability to repair uv-irradiated phages T/sub 1/, T/sub 3/, and T/sub 7/ There is a very small enhancement of T4 survival, but no measurable increase in the survivals of uv-irradiated phage T/sub 6/ or the HCR-susceptible type of phage T/sub 5/. The HRH property applies also to T/sub 3/ or T/sub 7/ phage inactivated by 8- methoxypsoralen plus long wavelength uv, methyl methanesulfonate, and ethyl methanesulfonate, but not, to any marked extent, to inactivating damage to these phages caused by nitrous acid on di-epoxybutane. The HRH mutant shows enhanced uv-reactivation ability compared with its B/r parent, but MMS-treated phage T/sub 3/ survives the secondary effects of methylation, possibly depurination, less well on the HRH than on the B/r host. A speculative hypothesis to explain these findings is that the HRH mutant lacks an exonuclease which normally limits the efficiency of the excision repair of phage, but not bacterial, DNA. (auth)

• Research Organization: Univ. of East Anglia, Norwich, Eng.
• NSA Number: NSA-29-000586
• OSTI ID: 4437557
• Journal Information: Stud. Biophys., v. 36-37, pp. 325-342, Journal Name: Stud. Biophys., v. 36-37, pp. 325-342; ISSN STBIB
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

*BACTERIOPHAGES-- BIOLOGICAL REPAIR
*ESCHERICHIA COLI-- RADIOSENSITIVITY
BIOLOGICAL RADIATION EFFECTS
HETEROCYCLIC COMPOUNDS
MUTANTS
N48310* --Life Sciences--Radiation Effects on Microorganisms- -Basic Studies
ORGANIC OXYGEN COMPOUNDS
PHOTON BEAMS
SURVIVAL TIME
ULTRAVIOLET RADIATION