luxA Gene From Enhygromyxa salina Encodes a Functional Homodimeric Luciferase

Area of Science:

• Biochemistry
• Microbiology
• Structural Biology

Background:

• Bacterial luminescence typically relies on heterodimeric luciferases encoded by luxA and luxB genes.
• Genomic analysis revealed bacterial species with reduced lux operons lacking the luxB gene.

Purpose of the Study:

• To investigate the luminescent properties and structure of LuxA from Enhygromyxa salina (EsLuxA) in bacteria with a rearranged lux operon.
• To explore the evolutionary origins of bacterial luciferases and their gene arrangements.

Main Methods:

• In vivo and in vitro luminescence assays of EsLuxA.
• Crystal structure determination of EsLuxA at 2.71 Å resolution.
• Phylogenetic analysis of EsLuxA and related proteins.

Main Results:

• EsLuxA exhibits luminescence upon aldehyde addition, functioning as a single-gene luciferase.
• EsLuxA shows lower brightness than established luciferases and prefers medium-chain aldehydes.
• Crystal structure reveals a TIM-barrel fold and unique helical structures in a mobile loop.
• Phylogenetic analysis suggests EsLuxA represents a potential ancestral protoluciferase.

Conclusions:

• EsLuxA demonstrates the functional capacity of a single-gene bacterial luciferase.
• The structural and phylogenetic findings provide insights into luciferase evolution.
• This work opens avenues for developing novel, single-gene bioluminescent reporters.