Previous Article | Next Article ![]()
J. Bacteriol., Jun 1995, 3027-3035, Vol 177, No. 11
C Mackenzie, M Chidambaram, EJ Sodergren, S Kaplan and GM Weinstock
The genome of the photosynthetic eubacterium Rhodobacter sphaeroides 2.4.1
comprises two chromosomes and five endogenous plasmids and has a 65% G+C
base composition. Because of these characteristics of genome architecture,
as well as the physiological advantages that allow this organism to live in
sunlight when in an anaerobic environment, the sensitivity of R.
sphaeroides to UV radiation was compared with that of the more extensively
studied bacterium Escherichia coli. R. sphaeroides was found to be more
resistant, being killed at about 60% of the rate of E. coli. To begin to
analyze the basis for this increased resistance, a derivative of R.
sphaeroides, strain 2.4.1 delta S, which lacks the 42-kb plasmid, was
mutagenized with a derivative of Tn5, and the transposon insertion mutants
were screened for increased UV sensitivity (UVs). Eight UVs strains were
isolated, and the insertion sites were determined by contour-clamped
homogeneous electric field pulsed-field gel electrophoresis. These mapped
to at least five different locations in chromosome I. Preliminary analysis
suggested that these mutants were deficient in the repair of DNA damage.
This was confirmed for three loci by DNA sequence analysis, which showed
the insertions to be within genes homologous to uvrA, uvrB, and uvrC, the
subunits of the nuclease responsible for excising UV damage.
Copyright © 1995, American Society for Microbiology
DNA repair mutants of Rhodobacter sphaeroides
Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston 77225, USA.
This article has been cited by other articles:
| Appl. Environ. Microbiol. | Infect. Immun. | Eukaryot. Cell |
|---|---|---|
| Mol. Cell. Biol. | J. Virol. | Microbiol. Mol. Biol. Rev. |
| ALL ASM JOURNALS |