FIGURE 2.

Protection of DnaJ tryptic sites by RepE binding. A and B, isolated RepE (20 μm), DnaJ (20 μm), and their preformed complex were digested at 1:200 (A) and 1:40 (B) trypsin:protein ratios (w:w). Digestions were performed at 30 °C for different times, and stopped by addition of 1 mm PMSF. Digestion products were resolved in 12.5% SDS-PAGE and detected by Coomassie staining. C, three-dimensional scheme of DnaJ showing tryptic sites that give rise to protein fragments >20 kDa. The model was built in PyMOL using the three-dimensional structure of DnaJ J-domain (Protein Data Bank code 1xbl), DnaJ cysteine-rich domain (Protein Data Bank code 1exk) and S. cerevisiae Ydj1 C-terminal fragment (Protein Data Bank code 1nlt).