InterPro domain: IPR003462

This entry represents the bacterial ornithine cyclodeaminase enzyme family, which catalyse the deamination of ornithine to proline [ 1 ]. The family also includes archaeal alanine dehydrogenase [ 2 ] and mu-crystallin, a mammalian homologue of bacterial ornithine cyclodeaminase [ 3 ], which is the major component of the eye lens in several Australian marsupials. mRNA for mu-crystallin has also been found in human retina [ 4 ].

This entry also includes protein SAR DEFICIENT 4 (SARD4) from Arabidopsis. SARD4 is involved in the biosynthesis of pipecolate (Pip), a metabolite that orchestrates defense amplification, positive regulation of salicylic acid (SA) biosynthesis, and priming to guarantee effective local resistance induction and the establishment of systemic acquired resistance (SAR) [ 4 ]. It does not possess ornithine cyclodeaminase activity in vitro [ 5 ].

1. Ornithine cyclodeaminase from octopine Ti plasmid Ach5: identification, DNA sequence, enzyme properties, and comparison with gene and enzyme from nopaline Ti plasmid C58. J. Bacteriol. 171, 847-54
2. A novel archaeal alanine dehydrogenase homologous to ornithine cyclodeaminase and mu-crystallin. J. Bacteriol. 186, 7680-9
3. mu-crystallin is a mammalian homologue of Agrobacterium ornithine cyclodeaminase and is expressed in human retina. Proc. Natl. Acad. Sci. U.S.A. 89, 9292-6
4. Characterization of a Pipecolic Acid Biosynthesis Pathway Required for Systemic Acquired Resistance. Plant Cell 28, 2603-2615
5. Functional characterization of an ornithine cyclodeaminase-like protein of Arabidopsis thaliana. BMC Plant Biol. 13, 182