FIG. 1.

Urease activity and RT-PCR results for the Sakai ureD mutants. (A, B, and D) Lanes: 1, Sakai; 2, Sakai Δure; 3, Sakai ureD(Q); 4, Sakai Δure attTn7::ure (chromosomal complement of Sakai Δure; unpublished work); 5, E. coli MG1655; 6, EHEC IN1; 7, EHEC Mo28; 8, Sakai ureD(P,Q). (A) Cultures were grown overnight in DMEM supplemented with NiCl₂, and the urease activities of cell lysates were measured. EHEC strains IN1 and Mo28 were used as positive controls, and MG1655 was used as a negative control. (B) RNA from overnight cultures was extracted and used for ureD RT-PCR experiments. (C) Sakai ureD(Q) harboring empty plasmid, pLLamber, or pLLQ was grown overnight, diluted 1:100 in M9 minimal medium supplemented with NiCl₂ and ampicillin, grown to an OD₆₀₀ of 0.45, induced with arabinose, and then grown for an additional 4 h. The urease activities of the Sakai ureD(Q) cell lysates were measured. The urease activity in lysates of Sakai ureD(Q) harboring pLLamber (the Sakai wild-type ureD) remained negligible at all concentrations of arabinose; thus, only that for 0.2% is included. (D) RNA from overnight cultures was extracted and used for detecting the transcript by RT-PCR.