Figure 4.

Enzymatic properties of purified rhomboid. (A) Rhomboid-catalysed cleavage is ATP independent. Cleavage assay with Ni²⁺-NTA purified YqgP (lane 1–3) and GlpG (lane 5–7); lanes 2 and 6, assay after ATP depletion; lanes 3 and 7, assay in the presence of an ATP regeneration system; lane 4, buffer only. (B–D) Comparative analysis of Ni²⁺-NTA purified YqgP mutants. Numbering refers to reaction time (min); b, control with buffer alone. (E) Progression curves of three independent cleavage assays with the indicated mutants; mean and range are indicated. Similar results were obtained with a second independent expression and purification (data not shown). (F) SDS–PAGE and Coomassie staining of Ni²⁺-NTA purified YqgP mutants.