Structure at 1.9 Å Resolution of a Quinohemoprotein Alcohol Dehydrogenase from Pseudomonas putida HK5

AbstractThe type II quinohemoprotein alcohol dehydrogenase of Pseudomonas putida is a periplasmic enzyme that oxidizes substrate alcohols to the aldehyde and transfers electrons first to pyrroloquinoline quinone (PQQ) and then to an internal heme group. The 1.9 Å resolution crystal structure reveals that the enzyme contains a large N-terminal eight-stranded β propeller domain (∼60 kDa) similar to methanol dehydrogenase and a small C-terminal c-type cytochrome domain (∼10 kDa) similar to the cytochrome subunit of p-cresol methylhydoxylase. The PQQ is bound near the axis of the propeller domain about 14 Å from the heme. A molecule of acetone, the product of the oxidation of isopropanol present during crystallization, appears to be bound in the active site cavity