Schmitz H, Crook KE, Jr., Bush JA. 1 L Luria-Bertani media supplemented with 50 g/mL kanamycin to an OD600 of 0.6-0.8. At that point, protein expression was induced by the addition of 0.1 mM IPTG at 18 C overnight. Cells were harvested by centrifugation (5000 rpm 30 min), resuspended in 50 mL buffer A (50 mM Tris-Cl pH 7.5, 300 mM NaCl, and 10% glycerol) at 4 C, and lysed on ice by sonication (5 30 sec pulses). Cell debris were removed by centrifugation (14000 rpm 45 min) followed by binding of lysate supernatant to 3 mL nickel IMAC resin (Bio-Rad) in batch-mode at 4 C. Bound protein was washed with 10 mL of 10 mM imidazole in buffer A and then with 20 mL of 20 mM imidazole in buffer A. HedCH999/pRJC006 spores has been described previously (24). Briefly, spores were produced in 50 mL Super YEME made up of 50 g/mL kanamycin for 3 days at 30 C shaking at 250 rpm. The mycelia were then transferred to 500 mL Super YEME made up of 50 g/mL kanamycin and produced as before for 2 days. Protein expression was induced by the addition of 5 g/mL thiostrepton, and the cell growth continued as before for 1 day. Cells were harvested by centrifugation (5000 rpm 30 min), resuspended in 40 mL lysis buffer (100 mM KPi pH 7.5, 0.1% Triton X-100, 5 mM TCEP, 1.5 mM benzamidine, 1 tablet EDTA-free protease inhibitor cocktail [Roche], and 10% glycerol), and lysed on ice by sonication (8 1 min AZD-5991 S-enantiomer pulses). Cell debris were removed by centrifugation (14000 rpm 30 min) followed by Rabbit Polyclonal to ZNF134 binding of lysate supernatant to 3 mL nickel IMAC resin AZD-5991 S-enantiomer (Bio-Rad) in batch-mode by spinning at 4 C for 2 hrs. Protein was eluted with increasing concentrations of imidazole in 100 mM KPi pH 7.5, 500 mM NaCl, and 10% glycerol. Fractions containing BAP1 cells (25) expressing pTLF-569 (C17S MAT was expressed and purified from BL21(DE3)/pGFL16 by nickel IMAC as described previously (26). In Vitro and Rfree were 0.186 and 0.248, respectively. The quality of the final structure was analyzed with Procheck (32). All crystallographic statistics are listed in Table 3. Table 3 HedHedActassay sections). Open in a separate window Figure 3 Sequence alignment among various type II PKS KRs. Sequences included hedamycin, actinorhodin, frenolicin, granaticin, griseucin, nogalamycin, oxytetracycline, and urdamycin KRs. AZD-5991 S-enantiomer Key: magenta circles, SDR cofactor-binding motif; blue arrow, arginine patch residue; yellow rectangles, SDR motif involved in the stabilization of the central -sheet; green-tinted box, PGG motif; red stars, catalytic residue. Table 2 Kinetic Parameters for the Oxidation of PKS. Corroborating the above hypothesis, the for the oxidation of HedActreductase activity, assay result is consistent with sequence-based prediction, that the change of the NNAG motif of min PKS), and if the ketoreduction still occurs at the C9-carbonyl group. To determine whether the C9-specificity is promoted by PKS reconstitution assays, in which purified MAT, and holo-min PKS + assay result of protein expression and product characterization; the present study indicates and is capable of regiospecific C9-ketoreduction of a 16-carbon polyketide chain. The above result supports that AZD-5991 S-enantiomer the C9-regiospecificity of type II polyketide KR is not closely related to the number of carbons (referred to as chain length throughout the text) of the incoming polyketide substrate. Open in a separate window Figure 4 HPLC analysis of products from reconstitution assays, demonstrating that min PKS) at the C9-position to form mutactin (4). Actenzyme activity between reduction of activity,.