VS111      Source of Strain:
F- Chromosomal Markers: λ-
, rph-1Strain Comments:
- This strain grows at 37-42 C in L + 15 ug/ml chloramphenicol
- 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
- Stupina, V.A., J.C. Wang 2005. Viability of Escherichia coli topA mutants lacking DNA topoisomerase I. J.Biol.Chem. 280:355-360