CELLULAR-LOCALIZATION BY IMMUNOLABELING AND TRANSMISSION ELECTRON-MICROSCOPY OF OXALOACETATE DECARBOXYLASE OR ITS INDIVIDUAL SUBUNITS SYNTHESIZED IN ESCHERICHIA-COLI

The genes oadGAB encoding the oxaloacetate decarboxylase gamma, alpha and beta-subunits from Klebsiella pneumoniae were expressed in Escheri chia coli. Using different expression vectors, the entire enzyme or it s individual subunits were synthesised. The expression was evidenced i mmunologically in whole cells with polyclonal antibodies raised agains t the purified oxaloacetate decarboxylase. The expressed alpha-subunit or a combination of alpha and beta-subunits were shown to reside in t he cytoplasm, while the entire oxaloacetate decarboxylase or a gamma a lpha-complex were located mostly in the cytoplasmic membrane. Interest ingly, overexpression of the gamma alpha-complex or the entire oxaloac etate decarboxylase in E. coli led to a significant immunogold labelli ng in the cytoplasm, indicating that the alpha-subunit was not complet ely complexed to the membrane-bound gamma or beta gamma-subunits.