Identification of long-chain alkane-degrading (LadA) monooxygenases in analysis.

Efficient degradation of alkanes in crude oil by the isolated MM1 alluded to the presence of highly active alkane-degrading enzymes in this fungus. A long-chain alkane-degrading, LadA-like enzyme family in was identified, and possible substrate-binding modes were analyzed using a computational approach. By analyzing publicly available protein databases, we identified six uncharacterized proteins in NRRL 3357, of which five were identified as class LadAα and one as class LadAβ, which are eukaryotic homologs of bacterial long-chain alkane monooxygenase (LadA). Computational models of LadAα homologs () showed overall structural similarity to the bacterial LadA and the unique sequence and structural elements that bind the cofactor Flavin mononucleotide (FMN). A receptor-cofactor-substrate docking protocol was established and validated to demonstrate the substrate binding in the LadAα homologs. The modeled , , and captured long-chain -alkanes inside the active pocket, above the bound FMN. Isoalloxazine ring of reduced FMN formed a π-alkyl interaction with the terminal carbon atom of captured alkanes, C-C, in 3-5 and C-C in 1. Our results confirmed the ability of identified LadAα monooxygenases to bind long-chain alkanes inside the active pocket. Hence . LadAα monooxygenases potentially initiate the degradation of long-chain alkanes by oxidizing bound long-chain alkanes into their corresponding alcohol.