FIG. 2.

Restoration of growth at 42°C to Ludox msbA mutants harboring a plasmid copy of wild-type msbA. Ludox msbA mutants were transformed with pWSK29 (−msbA) or pWTD10 (+msbA), and ampicillin-resistant colonies were streaked on LB-ampicillin (100 μg/ml) plates and grown overnight at 30 and 42°C. pWTD10 was constructed by cloning the XbaI/BamHI fragment from pWTD1 (7) into a similarly digested and dephosphorylated vector (pWSK29) (34). IPTG (isopropyl-β-d-thiogalactopyranoside) was not included in the growth media due to toxicity caused by overexpression of MsbA.