CGSC Strain#: 8229
Strain Designation: VS111-K2
Source of Strain: A.B. Khodursky
Sex: F-
Chromosomal Markers: λ-,
ΔtopA75,
zci-2234::cat,
Δfnr-267,
rph-1Strain Comments: - It may be necessary to transduce topA75 into MG1655 (again) or other strain, to observe the phenotype.
- The cold-sens. topA phenotype can be overcome by amplification of the Topo IV region (see below, Dorman et al., Raji et al., Khodursky).
- This strain was constructed by transduction of topA75 zci-2234::cat into MG1655.
- ΔtopA75-- : Strains can rapidly lose the phenoytpe by accumulation of secondary mutations. It may be necessary to transduce topA75 zci-2234::cat into MG1655 (or other) to observe phenotype.
- ΔtopA75-- deletes the promoter and the N-terminal part of TopI. It is able to grow normally at 42C, but at 30C with small inoculum, it grows poorly, no colonies are visible after 24 hr..
- zci-2234::cat-- is an insertion of cam at a unique SphI site in region 5' (counterclockwise) of the topA gene
- Δfnr-267-- was reported for MG1655 by pers.commun.from V.Stewart to B.Bachmann,1986, again to CGSC by V.S.2003. Some MG1655 subcultures and derivatives have it .See also Soupene et al. JBact.185:5611(2003).
- rph-1-- is a 1 bp deletion that results in frameshift over last 15 codons and has polar effect on pyrE leading to suboptimal pyrimidine levels on minimal medium.(Jensen 1993 JBact.175:3401)
- = chloramphenicol resistant
References: - Raji, A., D.J. Zabel, C.S. Laufer, R.E. Depew 1985. Genetic analysis of mutations that compensate for loss of Escherichia coli DNA topoisomerase I. J.Bacteriol. 162:1173-1179
- Dorman, CJ, AS Lynch, NN Bhriain, CF Higgins 1989. DNA supercoiling in Escherichia coli: topA mutations can be suppressed by DNA amplifications involving the tolC locus. Mol. Microbiol. 3(4):531-40.
- Stupina, V.A., J.C. Wang 2005. Viability of Escherichia coli topA mutants lacking DNA topoisomerase I. J.Biol.Chem. 280:355-360
- Khodursky, A.B. 2006. Pers.Commun.to MB 5:2006
- Khodursky, A.B. 2006. Pers.Commun.to MB 5:2006