Role of a small plasmid in the modification of carbon monoxide dehydrogenase in Pseudomonas carboxydovorans

Soluble fractions prepared from cells of Pseudomonas carboxydovorans bearing a small plasmid (1.76 × 10⁶) exhibited proteolytic activity on the β-subunit of CO dehydrogenase (CO-DH) in plasmid-cured cells of the same strain, implying that the plasmid carries gene(s) for processing the β subunit of the enzyme at the post-translational level. The protease was found to be a constitutive enzyme. It did not hydrolyze the β subunit of CO-DH in Pseudomonas carboxydohydrogena. Analysis of CO-DH after transformation of the cured cells with the small plasmid confirmed that the plasmid plays a role in the modification of the β subunit of CO-DH in P. carboxydovorans.