An alkane monooxygenase (AlkB) family in which all electron transfer partners are covalently bound to the oxygen-activating hydroxylase

Alkane monooxygenase (AlkB) is a non-heme diiron enzyme that catalyzes the hydroxylation of alkanes. It is commonly found in alkanotrophic organisms that can live on alkanes as their sole source of carbon and energy. Activation of AlkB occurs via two-electron reduction of its diferric active site, which facilitates the binding, activation, and cleavage of molecular oxygen for insertion into an inert C-H bond. Electrons are typically supplied by NADH via a rubredoxin reductase (AlkT) to a rubredoxin (AlkG) to AlkB, although alternative electron transfer partners have been observed. Here we report a family of AlkBs in which both electron transfer partners (a ferredoxin and a ferredoxin reductase) appear as an N-terminal gene fusion to the hydroxylase (ferr_ferrR_AlkB). This enzyme catalyzes the hydroxylation of medium chain alkanes (C6-C14), with a preference for C10-C12. It requires only NADH for activity. It is present in a number of bacteria that are known to be human pathogens. A survey of the genome neighborhoods in which is it found suggest it may be involved in alkane metabolism, perhaps facilitating growth of pathogens in non-host environments.

Automated summary

AlkB is an enzyme that catalyzes the hydroxylation of alkanes and is commonly found in organisms that can use alkanes as their sole source of carbon and energy. It is activated by two-electron reduction of its active site and can insert molecular oxygen into an inert C-H bond. A family of AlkBs has been identified with a unique gene fusion of electron transfer partners. This enzyme specifically hydroxylates medium chain alkanes, particularly C10-C12, and requires only NADH for activity. It is present in several human pathogens and may play a role in alkane metabolism and growth in non-host environments.