Figure 1. Cloning and expression of PPX mutants.

(a) Scheme of full-length PPX and PPX deletion mutants lacking various domains. Dark C-terminal squares represent the stop codons, and numbers on top indicate residues. All constructs were fused to an N-terminal 6xHis-tag. Affinity purified proteins were separated by SDS–polyacrylamide gel electrophoresis and visualized by (b) Coomassie brilliant blue staining or (c) western blotting with an antibody against the 6xHis-tag. A representative photographic film of three independent experiments is shown.