EXPRESSION OF SUBUNIT-A AND SUBUNIT-C OF THE SODIUM-DEPENDENT ATPASE OF PROPIONIGENIUM-MODESTUM IN ESCHERICHIA-COLI

The aim of the present study was to construct functional hybrid ATPase s consisting of all Escherichia coli ATPase subunits excepts the F-0 s ubunits a or c which were replaced by the respective subunits of the P ropionigenium modestum ATPase. This would give valuable information on the subunit(s) conferring the coupling ion specificity. Plasmids were constructed that carried the gene for subunit c (uncE) or subunit a ( uncB) behind a tac promoter. These plasmids were transformed into E. c oli strains which differed with respect to the une operon and the expr ession of the P. modestum genes was verified biochemically. Enhanced e xpression of the P. modestum genes led to strong growth inhibition of all E. coli strains tested. However, the expressed P. modestum protein s could not functionally complement E. coli strains that lacked the ho mologous subunit.