HOMOGENTISIC ACID IS THE PRODUCT OF MELA, WHICH MEDIATES MELANOGENESIS IN THE MARINE BACTERIUM SHEWANELLA-COLWELLIANA-D

Shewanella colwelliana D is a marine procaryote which produces a diffu sible brown pigment that correlates with melA gene expression. Previou sly, melA had been cloned, sequenced, and expressed in Escherichia col i; however, the reaction product of MelA had not been identified. This report identifies that product as homogentisic acid, provides evidenc e that the pigment is homogentisic acid-melanin (pyomelanin), and sugg ests that MelA is p-hydroxyphenylpyruvate hydroxylase. This is the fir st report of pyomelanin in an obligate marine bacterium.