| Type: | Family | Name: | LL-diaminopimelate aminotransferase, plants and Chlamydia type |
| Description: | Two lysine biosynthesis pathways evolved separately in organisms, the diaminopimelic acid (DAP) and aminoadipic acid (AAA) pathways. The DAP pathway synthesizes L-lysine from aspartate and pyruvate, and diaminopimelic acid is an intermediate. This pathway is utilised by most bacteria, some archaea, some fungi, some algae, and plants. The AAA pathway synthesizes L-lysine from alpha-ketoglutarate and acetyl coenzyme A (acetyl-CoA), and alpha-aminoadipic acid is an intermediate. This pathway is utilised by most fungi, some algae, the bacterium Thermus thermophilus, and probably some archaea, such as Sulfolobus, Thermoproteus, and Pyrococcus. No organism is known to possess both pathways [].There four known variations of the DAP pathway in bacteria: the succinylase, acetylase, aminotransferase, and dehydrogenase pathways. These pathways share the steps converting L-aspartate to L-2,3,4,5- tetrahydrodipicolinate (THDPA), but the subsequent steps leading to the production of meso-diaminopimelate, the immediate precursor of L-lysine, are different [].The succinylase pathway acylates THDPA with succinyl-CoA to generate N-succinyl-LL-2-amino-6-ketopimelate and forms meso-DAP by subsequent transamination, desuccinylation, and epimerization. This pathway is utilised by proteobacteria and many firmicutes and actinobacteria. The acetylase pathway is analogous to the succinylase pathway but uses N-acetyl intermediates. This pathway is limited to certain Bacillus species, in which the corresponding genes have not been identified. The aminotransferase pathway converts THDPA directly to LL-DAP by diaminopimelate aminotransferase (DapL) without acylation. This pathway is shared by cyanobacteria, Chlamydia, the archaeon Methanothermobacter thermautotrophicus, and the plant Arabidopsis thaliana. The dehydrogenase pathway forms meso-DAP directly from THDPA, NADPH, and NH4 _ by using diaminopimelate dehydrogenase (Ddh). This pathway is utilised by some Bacillus and Brevibacterium species and Corynebacterium glutamicum. Most bacteria use only one of the four variants, although certain bacteria, such as C. glutamicum and Bacillus macerans, possess both the succinylase and dehydrogenase pathways.This group of the superfamily of aminotransferases includes several which are adjacent to elements of the lysine biosynthesis via diaminopimelate pathway (). This family includes characterised species in plants and Chlamydia. Every member of this family is from a genome which possesses most of the lysine biosynthesis pathway but lacks any of the known succinylases, desuccinylases, acetylases or deacetylases typical of the acylated versions of this pathway nor do they have the direct, NADPH-dependent enzyme (ddh). This entry represents LL-diaminopimelate aminotransferase, DapL, which is involved in the synthesis of meso-diaminopimelate (m-DAP or DL-DAP), required for both lysine and peptidoglycan biosynthesis. This enzyme catalyzes the direct conversion of tetrahydrodipicolinate to LL-diaminopimelate, a reaction that requires three enzymes in E.coli. It is also able to use meso-diaminopimelate, cystathionine, lysine or ornithine as substrates []. | Short Name: | DapL_aminotrans |
