CGSC Strain#: 8178
Strain Designation: VS105      Source of Strain: V.A. Stupina
Sex: F- Chromosomal Markers: λ^-, lacZp-topA76(L5F C662H), zci-2234::cat, Δfnr-267, rph-1
Strain Comments:

• This strain will grow at 37-42 C in LB + 15 ug/ml chloramphenicol, but for growth at 30C, it also requires 1 mM IPTG
• lacZp-topA76(L5F C662H)-- replaces promoter topAp of allele topA78(G65N W79S substitutions in TopoI) with lacZp, resulting in an IPTG requirement for expression.
• lacZp-topA76(L5F C662H)-- : poor growth at 30C in absence of IPTG; At 42C, TopoI level is low and more negative supercoiling is observed, but the strain grows if it is topB⁺.
• 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
• L5F C662H = amino acid changes in TopoI

References:

• Stupina, V.A., J.C. Wang 2005. Viability of Escherichia coli topA mutants lacking DNA topoisomerase I. J.Biol.Chem. 280:355-360