Pathways & interactions
Succinyldiaminopimelate transaminase, DapC (IPR019877)
Short name: DapC
Overlapping homologous superfamilies
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 [PMID: 20418392].
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 [PMID: 20418392].
- 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.
The four sequences which make up the seed for this model are not closely related, although they are all members of the IPR004839 family of aminotransferases and are more closely related to each other than to anything else. Additionally, all of them are found in the vicinity of genes involved in the biosynthesis of lysine via the diaminopimelate pathway (GenProp0125), although this amounts to a separation of 12 genes in the case of Sulfurihydrogenibium azorense Az-Fu1. None of these genomes contain another strong candidate for this role in the pathway. Note: the detailed information included in the EC:22.214.171.124 record includes the assertions that the enzyme uses the pyridoxal pyrophosphate cofactor, which is consistent with the IPR004839 family, and the assertion that the amino group donor is L-glutamate, which is undetermined for the sequences in this clade.
- TIGR03537 (DapC)