Existence of a novel enzyme, pyrroloquinoline quinone-dependent polyvinyl alcohol dehydrogenase, in a bacterial symbiont, Pseudomonas sp. strain VM15C

Abstract

A novel enzyme, pyrroloquinoline quinone (PQQ)-dependent polyvinyl alcohol (PVA) dehydrogenase, was found in and partially purified from the membrane fraction of a PVA-degrading symbiont, Pseudomonas sp. strain VM15C. The enzyme required PQQ for PVA dehydrogenation with phenazine methosulfate, phenazine ethosulfate, and 2,6-dichlorophenolindophenol as electron acceptors and did not show PVA oxidase activity leading to H202 formation. The enzyme was active toward low-molecular-weight secondary alcohols rather than primary alcohols. A membrane-bound PVA oxidase was also present in cells of VM15C. Although the purified oxidase showed a substrate specificity similar to that of PQQ-dependent PVA dehydrogenase and about threefold-higher PVA-dehydrogenating activity with phenazine methosulfate or phenazine ethosulfate than PVA oxidase activity with H202 formation, it was shown that the enzyme does not contain PQQ as the coenzyme, and PQQ did not affect its activity. Incubation of the membrane fraction of cells with PVA caused a reduction in the cytochrome(s) of the fraction.

Biodegradability of poly(vinyl acetate) containing a pyridinium group

“…The polymer contained 0.9 mol % of the pyridyl group that did not react with benzyl chloride during the preparation procedure and remained unchanged in the polymer. After 492 days of the biological treatment, however, 4 6 8 10 12…”

Pyrroloquinoline Quinone-Dependent Cytochrome Reduction in Polyvinyl Alcohol-Degrading Pseudomonas sp. Strain VM15C

“…PVA dehydrogenase utilizes artificial electron acceptors such as phenazine ethosulfate (PES) but not 02 (9). PVA oxidase also utilizes artificial electron acceptors, besides 02, and shows PVA dehydrogenase activity (9). PVA dehydrogenase is a membrane-bound enzyme, and PVA oxidase is also partly present in the membrane of this bacterium (9,10,13).…”

“…However, the involvement of PQQ in PVA oxidation does not conclusively demonstrate that PQQ is an essential growth factor for PVA utilization, because the strain has another type of PVA-oxidizing enzyme, PVA oxidase (10, 12, 13), as do other PVA-degrading bacteria (5,15). PVA oxidase does not utilize PQQ as a coenzyme, but the two enzymes have similar substrate specificities (9). PVA dehydrogenase utilizes artificial electron acceptors such as phenazine ethosulfate (PES) but not 02 (9).…”

“…strain VM15C, a polyvinyl alcohol (PVA)-degrading bacterium, which is a component strain of a symbiotic mixed culture (6,11), requires pyrroloquinoline quinone (PQQ) as an essential growth factor for PVA utilization (7,8,14). PQQ acts as a vitamin for the strain and as a coenzyme for a novel PVA-oxidizing enzyme, PVA dehydrogenase (9), which is also the first example of a secondary alcohol dehydrogenase among quinoprotein enzymes (2). However, the involvement of PQQ in PVA oxidation does not conclusively demonstrate that PQQ is an essential growth factor for PVA utilization, because the strain has another type of PVA-oxidizing enzyme, PVA oxidase (10, 12, 13), as do other PVA-degrading bacteria (5,15).…”

“…PVA oxidase does not utilize PQQ as a coenzyme, but the two enzymes have similar substrate specificities (9). PVA dehydrogenase utilizes artificial electron acceptors such as phenazine ethosulfate (PES) but not 02 (9). PVA oxidase also utilizes artificial electron acceptors, besides 02, and shows PVA dehydrogenase activity (9).…”