Identification and characterization of a fluorescent flagellar protein from the brown alga Scytosiphon lomentaria (Scytosiphonales, Phaeophyceae): A flavoprotein homologous to Old Yellow Enzyme

Abstract

The posterior flagellum of the zoospore of the brown alga Scytosiphon lomentaria exhibits bright green autofluorescence. To identify the fluorescent flagellar substance(s), we isolated flagella from zoospores and partially purified a flavoprotein by anion-exchange and gel-filtration chromatography. Spectrofluorometric and chromatographic analyses showed that the flavoprotein had an apparent molecular mass of 41 kDa and a non-covalently bound flavin mononucleotide as a chromophore. Based on partial amino acid sequences of the protein, a cDNA of the 41-kDa flavoprotein was cloned and sequenced. The deduced amino acid sequence of the cDNA was homologous to that of the Old Yellow Enzyme family distributed in proteobacteria, yeasts and vascular plants.