FIG. 6.
Plasmid construction. Plasmid pthiCH was isolated as described in the text. BamHI (B) digestion allowed individual subcloning of thiH on a 2.4-kb fragment, generating plasmid pthiH. The insert of pthiH was ligated into BamHI-cut pGEM7 (Promega), generating plasmids pthiH-7(+) and pthiH-7(−), with thiH in the correct orientation for expression from the T7 promoter and from the lac promoter, respectively. Plasmid pthiES1 was generated via BamHI and EcoRI (E) digestion of pthiCH and ligation into pSU18. Black arrows represent complete ORFs, and boxes represent vector DNA.