This clade of mainly archaeal and related bacterial species contains two characterized enzymes, an deacetylase with specificity for both N-acetyl-ornithine and N-acetyl-lysine from Thermus, which is found within a lysine biosynthesis operon, and a fusion protein with acetyl-glutamate kinase (an enzyme of ornithine biosynthesis) from Lactobacillus. It is possible that all of the sequences within this clade have dual specificity, or that a mix of specificities have evolved within this clade.
Jiyao W et al.(2023). "The conserved domain database in 2023.",