Crystal structure of long-chain alkane monooxygenase (LadA) in complex with coenzyme FMN: unveiling the long-chain alkane hydroxylaseLi, L., Liu, X., Yang, W., Xu, F., Wang, W., Feng, L., Bartlam, M., Wang, L., Rao, Z.
(2008) J Mol Biol 376: 453-465
- PubMed: 18164311
- DOI: https://doi.org/10.1016/j.jmb.2007.11.069
- Primary Citation of Related Structures:
- PubMed Abstract:
LadA, a long-chain alkane monooxygenase, utilizes a terminal oxidation pathway for the conversion of long-chain alkanes (up to at least C(36)) to corresponding primary alcohols in thermophilic bacillus Geobacillus thermodenitrificans NG80-2. Here, we report the first structure of the long-chain alkane hydroxylase, LadA, and its complex with the flavin mononucleotide (FMN) coenzyme. LadA is characterized as a new member of the SsuD subfamily of the bacterial luciferase family via a surprising structural relationship. The LadA:FMN binary complex structure and a LadA:FMN:alkane model reveal a hydrophobic cavity that has dual roles: to provide a hydrogen-bond donor (His138) for catalysis and to create a solvent-free environment in which to stabilize the C4a-hydroperoxyflavin intermediate. Consequently, LadA should catalyze the conversion of long-chain alkanes via the acknowledged flavoprotein monooxygenase mechanism. This finding suggests that the ability of LadA to catalyze the degradation of long-chain alkanes is determined by the binding mode of the long-chain alkane substrates. The LadA structure opens a rational perspective to explore and alter the substrate binding site of LadA, with potential biotechnological applications in areas such as petroleum exploration and treatment of environmental oil pollution.
Tsinghua-Nankai-IBP Joint Research Group for Structural Biology, Tsinghua University, Beijing 100084, China.