Aromatic amino acid lyase (IPR001106)
Short name: Aromatic_Lyase
Overlapping homologous superfamilies
- L-Aspartase-like (IPR008948)
- Phenylalanine ammonia-lyase, shielding domain superfamily (IPR023144)
- Aromatic amino acid lyase (IPR001106)
- Histidine ammonia-lyase (IPR005921)
- Phenylalanine aminomutase (D-beta-phenylalanine forming) (IPR031007)
- Phenylalanine ammonia-lyase (IPR005922)
- Tyrosine 2,3-aminomutase, putative (IPR022314)
This family includes phenylalanine ammonia-lyase, (PAL; EC:22.214.171.124), histidine ammonia-lyase, (HAL; EC:126.96.36.199), and tyrosine aminomutase, (EC:188.8.131.52) [PMID: 7925471, PMID: 10220322, PMID: 16793524].
PAL and HAL are members of the Lyase class I_like superfamily of enzymes that, catalyze similar beta-elimination reactions and are active as homotetramers. Both PAL and HAL contain a catalytic Ala-Ser-Gly triad that is post-translationally cyclised [PMID: 16478474]. PAL is a key biosynthetic catalyst in phenylpropanoid assembly in plants and fungi, and is involved in the biosynthesis of a wide variety of secondary metabolites such as flavanoids, furanocoumarin phytoalexins and cell wall components. These compounds are important for normal growth and in responses to environmental stress. HAL catalyses the first step in histidine degradation, the removal of an ammonia group from histidine to produce urocanic acid. The core domain in PAL and HAL share about 30% sequence identity, with PAL containing an additional approximately 160 residues extending from the common fold [PMID: 15350127]. Tyrosine 2,3-aminomutase has aminomutase activity and, to a much lesser extent, ammonia-lyase activity [PMID: 19222035].
PAL is being explored as enzyme substitution therapy for Phenylketonuria (PKU), a disorder which involves an inability to metabolize phenylalanine. HAL failure in humans results in the disease histidinemia [PMID: 11578924, PMID: 12502351, PMID: 12667480, PMID: 11895450].