Figure 2

Domain structure of P. aeruginosa topoisomerase I. (A) Schematic representation of the tripartite structure predicted for the 333 amino acid P. aeruginosa topoisomerase I is illustrated using the Vaccinia topoisomerase IB as a template. The mutant protein lacking the 98-residue N-terminal domain is the catalytic fragment (PATCAT, residues 99–333). For the active site tyrosine mutant, the active site tyrosine is changed to phenylalanine (referred to as the Y292F mutant protein). (B) P. aeruginosa topoisomerase I wild type purified. The enzyme fraction was analyzed by SDS-PAGE. In lane 1 is the molecular weight marker, lane 2 shows the PAT. (C) P. aeruginosa topoisomerase I catalytic fragment purified, lane 1 shows the molecular marker and lane 2 shows the PATCAT (D) P. aeruginosa topoisomerase tyrosine mutant purified, lane 1 shows the molecular weight marker and lane 2 shows the Y292F mutant protein.