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. 2013 Feb 21;8(2):e56906. doi: 10.1371/journal.pone.0056906

Figure 3. Conversion of galacturonate and glucuronate by cell-free extracts of E. coli overexpressing KduI and KduD.

Figure 3

Conversion of galacturonate (A, B) and glucuronate (C, D) by cell-free extracts from E. coli overexpressing KduI (E. coli KRX pGEM-T-kduI), KduD (E. coli KRX pGEM-T-kduD), or both (E. coli JM109 pGEM-T-kduID) was investigated. E. coli strains were selected according to the orientation of the cloned gene: expression in E. coli KRX was controlled by the T7-RNA-polymerase and induced by rhamnose (0.1%). Expression in E. coli JM109 was controlled by the lacZ-promoter and induced by addition of IPTG (1 mM). E. coli containing the empty vector served as a control. The reactions were started by addition of 10 mM galacturonate or glucuronate and incubation at 37°C. Concentration of hexuronates was measured enzymatically. Broken black line, E. coli JM109 pGEM-T (A, C), E. coli KRX pGEM-T (B, D) (negative controls); black line, E. coli JM109 pGEM-T-kduID (A, C); gray line, E. coli KRX pGEM-T-kduI; broken gray line, E. coli KRX pGEM-T-kduD (B, D). Data are expressed as median and 25% and 75% percentile (n = 11–12). The Mann-Whitney test was used for calculations. *, P<0.05; **, P<0.01; ***, P<0.001.