InterPro domain: IPR005786

Aminotransferases share certain mechanistic features with other pyridoxal-phosphate dependent enzymes, such as the covalent binding of the pyridoxal-phosphate group to a lysine residue. On the basis of sequence similarity, these various enzymes can be grouped [ 1 ] into subfamilies.

One of these, called class-IV, currently consists of proteins of about 270 to 415 amino-acid residues that share a few regions of sequence similarity. Surprisingly, the best conserved region does not include the lysine residue to which the pyridoxal-phosphate group is known to be attached, in ilvE, but is located some 40 residues at the C terminus side of the PlP-lysine.

Among the class IV aminotransferases are two phylogenetically separable groups of branched-chain amino acid aminotransferase (IlvE) ( 2.6.1.42 ). The last common ancestor of the two lineages appears also to have given rise to a family of D-amino acid aminotransferases (DAAT). This model represents the IlvE family less similar to the DAAT family.

Also included in this group is branched-chain amino acid aminotransferase gloG from the yeast Glarea lozoyensis , which is required for biosynthesis of the mycotoxin pneumocandin, a lipohexapeptide of the echinocandin family [ 2 ]. Transaminase AMT5 from the Alternaria rot fungus is one of many enzymes required for the non-ribosomal biosynthesis of the cyclic depsipeptides known as AM-toxins [ 3 ]. The aminotransferase FGSG_00049 from Fusarium graminearum is part of the gene cluster that mediates the biosynthesis of gramillins A and B, bicyclic lipopeptides that induce cell death in maize leaves but not in wheat, suggesting host-specific adaptation [ 4 ].

1. Characterization and sequence of Escherichia coli pabC, the gene encoding aminodeoxychorismate lyase, a pyridoxal phosphate-containing enzyme. J. Bacteriol. 174, 5317-23
2. Structural diversity in echinocandin biosynthesis: the impact of oxidation steps and approaches toward an evolutionary explanation. Z. Naturforsch., C, J. Biosci. 72, 1-20
3. Expression profiles of genes encoded by the supernumerary chromosome controlling AM-toxin biosynthesis and pathogenicity in the apple pathotype of Alternaria alternata. Mol. Plant Microbe Interact. 20, 1463-76
4. Gramillin A and B: Cyclic Lipopeptides Identified as the Nonribosomal Biosynthetic Products of Fusarium graminearum. J. Am. Chem. Soc. 140, 16783-16791