Lysine (thing)

Anabolic biosynthesis of Lysine is unusual among amino acids in that there are two dissimilar pathways of production.

One is the diaminopimelic acid pathway (DAP), and the other is the α-aminoadipic acid route (AAA).

What is interesting is that they are completely dissimilar, using different enzymes and having evolved separately in different lineages of life.

The diaminopimelic acid pathway is most commonly found in Plants - Kingdom Plantae but can pretty much be considered universal.

The less common α-aminoadipic acid route (AAA). was once though to be unique to fungi¹. But it has since been discovered in at least two other groups:

• The extremely thermophilic Gram-negative bacterium, Thermus thermophilus and relatives.
• The Euglenids, for example Euglena, one of the basal Eukaryotes,a photosynthetic flagellate, easy to find swimming around in a drop of pond water and notable for their conspicuous chloroplasts.

¹Parts of the AAA pathway of lysine degradation are also found in animals, contributing to the theory that the Animal and Fungal kingdoms are much more more closely related than Plants and Fungi, as was once assumed.

ref: Journal of Molecular Evolution DOI: 10.1007/s00239-002-2340-2 © Springer-Verlag New York Inc. 2002 Molecular Evolution of the Lysine Biosynthetic Pathways A.M. Velasco, J.I. Leguina, and A. Lazcano