The phylogenetic analysis and putative function of lysine 2,3-aminomutase from methanoarchaea infers the potential biocatalysts for the synthesis of β-lysine

Backgroundβ-amino acids play important biological roles as precursors in the biosynthesis of antibiotics, anticancer agents, neurotransmitters, and other high molecular weight polymers. Microbial cells and enzymes from extreme environments offer new opportunities for biocatalysis and biotransformations as a result of their extreme stability. Lysine 2,3-aminomutase catalyzes the interconversion of L-α-lysine and L-β-lysine. L-β-lysine is a precursor in the bacterial biosynthesis of several antibiotics, and also is a precursor in the biosynthesis of osmolyte Nε-acetyl-β-lysine for salt stress and adaptation in methanoarchaea.MethodsLysine 2,3-aminomutase (AblA) genes from the marine Methanosarcina mazei N2M9705, halotolerant Methanocalculus chunghsingensis K1F9705bT, and halophilic Methanohalophilus portucalensis FDF1T were cloned by PCR and southern hybridization. Both nucleotide and amino acid sequences of AblAs were analyzed and phylogenetic comparisons performed. Additionally, the functional motifs and 3D structure of aminomutases were aligned and compared.ResultsThe deduced amino acid sequences of AblAs from methanoarchaea share high identity with the known clostridial and Bacillus lysine 2,3-aminomutase. The conserved amino acid residues for cofactors, such as the iron-sulfur cluster, S-adenosylmethionine (SAM), pyridoxal 5'-phosphate (PLP) and zinc-binding sites in methanoarchaeal AblAs suggested that they were lysine 2,3-aminomutases.ConclusionAblAs from methanoarchaea are lysine 2,3-aminomutases that may function as potential biocatalysts for the synthesis of β-lysine in vivo and in vitro.