This factor may explain its notable affinity towards the glutathione-derivatized sepharose resin. Effects of pZ7C-GST plasmid maintenance on growth rates We next selleck inhibitor investigated whether the presence of the pZ7C-GST expression vector significantly affected the growth rates of the NCIMB 11163, ATCC 29191 and CU1 Rif2 stains. The cell doubling times were as follows: NCIMB 11163, 104 ± 7 minutes; NCIMB 11163/pZ7-GST, 139 ± 13 minutes; CU1 Rif2, 95 ± 4 minutes;
CU1 Rif2/pZ7C-GST, 111 ± 5 minutes; ATCC 29191, 85 ± 6 minutes; ATCC 29191/pZ7GST, 102 ± 9 minutes (Additional file 7). These results indicated that the maintenance of the pZ7C-GST expression vector led to only modest decreases in the growth rates (ca. 15-35%), compared to the respective wild type strains. Expression of GST-fusion proteins from pZ7C-derived vectors in E. coli and Z. mobilis To demonstrate the applicability of the pZMO7-derived shuttle vectors for proteomic and biotechnological applications in Z. mobilis, we selected five proteins for expression analysis and binding-interaction analysis in the ATCC 29191 strain: acyl-carrier protein (AcpP, ZZ6_0066; 78 aa), 2-dehydro-3-deoxyphosphooctonate aldolase (KdsA, ZZ6_1604; 292 aa), chaperone protein DnaJ (ZZ6_0618; 375 aa), RNA chaperone Hfq (ZZ6_0899; 161 aa) and DNA polymerase III chi subunit (HolC, ZZ6_0042;
cloned into the pZ7-GST expression vector, creating the respective N-terminal GST fusions: pZ7-GST-acpP; pZ7-GST-kdsA; pZ7-GST-dnaJ; pZ7-GST-hfq and pZ7-GST-holC. We first qualitatively determined the respective expression levels of the five pZ7-GST plasmid-encoded GST-fusion proteins within E. coli BL21 (DE3); including plasmid pZ7-GST as a positive control. SDS-PAGE gels of the cell lysate proteins eluted from the GST-affinity columns are shown in Additional file 8. It was found that the recombinant GST, GST-AcpP, GST-Hfq and GST-KdsA proteins were expressed to detectable levels; with levels of GST-AcpP being the highest. Plasmid-encoded GST-fusions of the DnaJ and HolC proteins were not expressed to visually detectable levels. Analogous protein expression experiments were then performed in the ATCC 29191 and CU1 Rif2 strains of Z. mobilis. To investigate whether there were significant differences in plasmid-based protein expression patterns during different metabolic/respiratory modes of growth, the respective wild type and transformed strains were cultured under both semi-aerobic and anaerobic conditions. SDS-polyacrylamide gels of the respective eluted fractions are shown in Figure 4, Panels A-D.