3 DISTINCT QUINOPROTEIN ALCOHOL DEHYDROGENASES ARE EXPRESSED WHEN PSEUDOMONAS-PUTIDA IS GROWN ON DIFFERENT ALCOHOLS

A bacterial strain that can utilize several kinds of alcohols as its s ole carbon and energy sources was isolated from soil and tentatively i dentified as Pseudomonas putida HK5. Three distinct dye-linked alcohol dehydrogenases (ADHs), each of which contained the prosthetic group p yrroloquinoline quinone (PQQ), were formed in the soluble fractions of this strain grown on different alcohols. ADH I was formed most abunda ntly in the cells grown ethanol and was similar to the quinoprotein AD H reported for P. putida (H. Gorisch and M. Rupp, Antonie Leeuwenhoek 56:35-45, 1989) except for its isoelectric point. The other two ADHs, ADH IIB and ADH IIG, were formed separately in the cells grown on l-bu tanol;and 1,2-propanediol, respectively. Both of these enzymes contain ed heme c in addition to PQQ and functioned as quinohemoprotein dehydr ogenases. Potassium ferricyanide was an available electron acceptor fo r ADHs IIB and IIG but not for ADH I. The molecular weights were estim ated to be 69,000 for ADH IIB and 72,000 for ADH IIG, and both enzymes were shown to be monomers. Antibodies raised against each of the puri fied ADHs could distinguish the ADHs from one another. Immunoblot anal ysis showed that ADH I was detected in cells grown on each alcohol tes ted, but ethanol was the most effective inducer. ADH IIB was formed in the cells grown on alcohols of medium chain length and also on 1,3-bu tanediol. Induction of ADH IIG was restricted to 1,2-propanediol or gl ycerol, of which the former alcohol was more effective. These results from immunoblot analysis correlated well with the substrate specificit ies of the respective enzymes. Thus, three distinct quinoprotein ADHs were shown to be synthesized by a single bacterium under different gro wth conditions.