Structure and Function of Alkane Monooxygenase (AlkB)

Area of Science:

• Biochemistry
• Environmental Microbiology

Background:

• Hydrocarbons, particularly alkanes, are abundant environmental pollutants.
• Organisms transform alkanes for energy and carbon, utilizing both aerobic and anaerobic pathways.
• Understanding alkane-transforming enzymes is crucial for bioremediation and the carbon cycle.

Approach:

• Focuses on the alkane monooxygenase (AlkB) enzyme, responsible for aerobic liquid alkane transformation.
• Reviews recent high-resolution cryo-electron microscopy (cryo-EM) structures of AlkB.
• Integrates functional studies, radical clock assays, and comparative analysis with related enzymes.

Key Points:

• The first structures of AlkB, a predominant aerobic alkane hydroxylase, were determined in 2023.
• Functional studies of single residue variants reveal how AlkB's structure facilitates its catalytic activity.
• Mechanistic studies using radical clock substrates characterize AlkB's reaction pathway.

Conclusions:

• Provides a holistic understanding of AlkB by integrating structural, functional, and mechanistic data.
• Highlights similarities and differences with other diiron enzymes.
• Identifies outstanding questions regarding the enzyme's active site electronic structure and broader biological roles.