Plant and animal glycolate oxidases have a common eukaryotic ancestor and convergently duplicated to evolve long-chain 2-hydroxy acid oxidases

Mol Biol Evol. 2014 May;31(5):1089-101. doi: 10.1093/molbev/msu041. Epub 2014 Jan 9.


Glycolate oxidase (GOX) is a crucial enzyme of plant photorespiration. The encoding gene is thought to have originated from endosymbiotic gene transfer between the eukaryotic host and the cyanobacterial endosymbiont at the base of plantae. However, animals also possess GOX activities. Plant and animal GOX belong to the gene family of (L)-2-hydroxyacid-oxidases ((L)-2-HAOX). We find that all (L)-2-HAOX proteins in animals and archaeplastida go back to one ancestral eukaryotic sequence; the sole exceptions are green algae of the chlorophyta lineage. Chlorophyta replaced the ancestral eukaryotic (L)-2-HAOX with a bacterial ortholog, a lactate oxidase that may have been obtained through the primary endosymbiosis at the base of plantae; independent losses of this gene may explain its absence in other algal lineages (glaucophyta, rhodophyta, and charophyta). We also show that in addition to GOX, plants possess (L)-2-HAOX proteins with different specificities for medium- and long-chain hydroxyacids (lHAOX), likely involved in fatty acid and protein catabolism. Vertebrates possess lHAOX proteins acting on similar substrates as plant lHAOX; however, the existence of GOX and lHAOX subfamilies in both plants and animals is not due to shared ancestry but is the result of convergent evolution in the two most complex eukaryotic lineages. On the basis of targeting sequences and predicted substrate specificities, we conclude that the biological role of plantae (L)-2-HAOX in photorespiration evolved by co-opting an existing peroxisomal protein.

Keywords: (L)-2-hydroxyacid oxidases; convergent evolution; glycolate oxidase; lactate oxidase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alcohol Oxidoreductases / chemistry
  • Alcohol Oxidoreductases / genetics*
  • Alcohol Oxidoreductases / metabolism*
  • Animals
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Evolution, Molecular*
  • Gene Duplication
  • Gene Transfer, Horizontal
  • Genes, Plant
  • Genetic Speciation
  • Models, Molecular
  • Phylogeny
  • Plants / enzymology*
  • Plants / genetics*
  • Protein Conformation
  • Structural Homology, Protein
  • Substrate Specificity
  • Symbiosis / genetics


  • Arabidopsis Proteins
  • Alcohol Oxidoreductases
  • glycollate oxidase