Supplementary Figure 4: Mycobacterium tuberculosis DnaE1 wild-type (DnaE1^MTB WT) and PHP mutants are properly folded.

(a) SDS-PAGE analysis of purified proteins. Each lane contains 3.5 pmol (~0.5 μg) protein. The gel was stained with Coomassie Brilliant Blue. (b) Purified proteins do not show any aggregation, as judged by size exclusion chromatography. The arrow indicates the void volume (at 0.8 ml). For clarity, graphs are shifted vertically by 150 mAU. (c) Circular dichroism spectra show that DnaE1^MTB and PHP mutants are properly folded. (d) Thermal denaturation curves show that WT and mutant DnaE1 have similar melting temperatures of 45–50 °C. (e) Time course of exonuclease activity on single-stranded DNA. DnaE1^MTB WT shows robust 3′–5′ exonuclease activity but not 5′–3′ exonuclease activity.