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The Genetics of the Vibrio Lux operon - a short introduction (adapted from wikipedia)

In V. fischeri five genes (LuxCDABE) have been identified as active in the emission of visible light, and two genes (LuxR and LuxI) are involved in regulating the operon. Several external and intrinsic factors appear to induce and inhibit the transcription of this gene set.

(Meighen, 1991) The lux operon is a 9 kilobase fragment .

The lux operon has a known gene sequence of luxCDAB(F)E, lux A and lux B code for the components of luciferase

lux CDE codes for a fatty acid reductase complex that makes the fatty acids necessary for the luciferase mechanism: Lux C codes for the enzyme acyl-reductase lux D codes for acyl-transferase lux E makes the proteins needed for the enzyme acyl-protein synthetase.

Luciferase produces blue/green light through the oxidation of reduced flavin mononucleotide and a long chain aldehyde by diatomic oxygen. Reaction: FMNH2 + O2 + R-CHO ------> FMN + R-COOH + H2O + Light (Silverman et al, 1984)

In order to generate the aldehyde needed in the reaction above, three additional enzymes are needed. The fatty acids needed for the reaction are pulled out from the fatty acid biosynthesis pathway by the enzyme acyl-transferase.

Acyl-trasferase reacts with acyl-ACP to release R-COOH, a free fatty acid.

R-COOH is reduced by a two-enzyme system to an adehyde.

Reaction: R-COOH + ATP + NADPH ------> R-CHO + AMP + PPi + NADP+ (Winfrey et al., 1997).

Although the lux operon encodes the enzymes necessary for the bacteria to glow, bioluminescence is regulated by autoinduction and quorum sensing.