A new lux gene in bioluminescent bacteria codes for a protein homologous to the bacterial luciferase subunits

The nucleotide sequence of a new gene, luxF, located between the luxB and E genes in the bioluminescent system of Photobacterium phosphoreum has been determined. The luxF gene codes for a polypeptide of 231 amino acids which is homologous to the α and β subunits of luciferase coded by the luxA and luxB genes, respectively. The degree of homology of the luxF protein is very high with the β subunit of luciferase (∼ 30% identity) with greatest similarity to the Vibrio luxB proteins. The luxF gene appears to have evolved by duplication of the luxB gene followed by deletion of approximately 100 codons just penultimate to the 5′-terminal. The close homology with the luciferase β subunit implicates the luxF protein in a function related to the light-emitting reaction.