(Upper panel) Western immunoblot analysis of MtaC and MtaA proteins expressed from synthetic PmcrB(tetO1)-mtaCBA operons. (Lower panel) Coomassie blue-stained polyacrylamide gel electrophoresis gel run with equal amounts of total protein from each extract. Lane 1, parental strain (WWM 148), from which all mta genes were deleted, grown on TMA; lane 2, PmcrB(tetO1)-mtaC2B2A1 (WWM170) strain, grown on TMA plus tetracycline; lane 3, PmcrB(tetO1)-mtaC2B2A1 (WWM170) strain, grown on methanol plus tetracycline; lane 4, PmcrB(tetO1)-mtaC1B1A1 (WWM176) strain grown on TMA plus tetracycline; lane 5, PmcrB(tetO1)-mtaC1B1A1 (WWM176) strain grown on methanol plus tetracycline; lane 6, PmcrB(tetO1)-mtaC3B3A1 (WWM184) strain, grown on TMA plus tetracycline; lane 7, PmcrB(tetO1)-mtaC3B3A1 (WWM184) strain, grown on methanol plus tetracycline; lane 8, control strain (WWM1), with all mta genes expressed from their native promoters, grown on methanol. For MtaC and MtaA detection, 4 μg and 0.5 μg total protein, respectively, were loaded in each well.