This is the N-terminal domain found in antimicrobial protein (LodA) with lysine-epsilon oxidase activity (EC 1.4.3.20) which is produced by gram-negative marine bacteria such as Marinomonas mediterranea [1]. The enzyme, previously named marinocine, catalyzes the oxidative deamination of l-lysine into 6-semialdehyde 2-aminoadipic acid, ammonia, and hydrogen peroxide (H2O2). Orthologous proteins have been detected in other bacterial genera, where they participate in biofilm development and dispersal [2]. It has been shown that M. mediterranea LodA and its homologues induce cell death in the microcolonies formed in the process of biofilm development due to the hydrogen peroxide generated by their enzymatic activity. Moreover, cells dispersed from the biofilm by means of this mechanism show a phenotypic variation in growth and biofilm formation. The active form of LodA containing the quinonic cofactor is generated intracellularly only in the presence of LodB, suggesting that the latter protein is involved in this process [3].

1: X-ray crystallographic evidence for the presence of the cysteine tryptophylquinone cofactor in L-lysine epsilon-oxidase from Marinomonas mediterranea. Okazaki S, Nakano S, Matsui D, Akaji S, Inagaki K, Asano Y; J Biochem. 2013;154:233-236. PMID:23908359

2: Determination of plasma and serum L-lysine using L-lysine epsilon-oxidase from Marinomonas mediterranea NBRC 103028(T). Matsuda M, Asano Y; Anal Biochem. 2010;406:19-23. PMID:20599635

3: Both genes in the Marinomonas mediterranea lodAB operon are required for the expression of the antimicrobial protein lysine oxidase. Gomez D, Lucas-Elio P, Solano F, Sanchez-Amat A; Mol Microbiol. 2010;75:462-473. PMID:20025674