Mycobacterium marinum is a slow-growing pathogenic mycobacterium. It was first isolated by Aronson in 1926 from fish, fish mycobacteriosis or called fish tuberculosis is the common causative agent of bacterial disease in many species of freshwater and marine fish. M. marinum can infect wild fish, aquaculture and ornamental fish, and it has a close relative of the causative agent of human tuberculosis, Mycobacterium tuberculosis. The recently sequenced genome of M. marinum has been shown to contain several putative GntR regulators. This family named after gluconate regulator has a helix-turn-helix structure. Characterization of transcription regulators and their network is an important step towards the complete understanding of cellular physiology. The regulator of this family shares a similar and conserved N-terminal DNA-binding domain, but has a highly diverse C-terminal effector-binding and oligomerization domain. According to the heterogeneity, we classify the M. marinum GntR family to four subfamilies: FadR, HutC, MocR, and YtrA, and these regulators are encoded by 8, 3, 1 and 1 genes, respectively. Thus this study extends the annotation of M. marinum GntR family proteins, and can help to understand the pathogenic role of this family in M. marinum and facilitate future drug design against this pathogen. (C) 2011 Elsevier Inc. All rights reserved.