Lysine metabolism in higher plants.

On the whole, the possible mechanism of regulation of the lysine biosynthetic and transport genes is similar to the previously proposed mechanisms of regulation of riboflavin, thiamin and vitamin B12 genes (–). Similarly to the previously established direct binding of an effector (flavin mononucleotide, thiamin pyrophosphate or adenosylcobalamin) to a highly conserved RNA element (RFN, THI or B12, respectively), we propose that lysine is an effector molecule for the LYS element, acting in a similar manner. In the repressing conditions of lysine excess, an adjacent regulatory hairpin, terminator or RBS-sequestor can fold that leads to the transcriptional or translational repression of the target genes. At low concentration of effector molecules, the unstable RNA element is replaced by an alternative anti-terminator or anti-sequestor RNA conformation allowing for transcription readthrough or translation initiation. Interestingly, the observed phylogenetic distribution of the LYS-element-associated terminators and sequestors in Gram-positive and Gram-negative bacteria, respectively, is similar to the previously observed distribution of the regulatory hairpins in the analyzed vitamin regulons ().

Outline of pathways of synthesis of essential amino acids.

The biosynthesis and metabolism of the aspartate derived amino acids in higher plants.

tabaci BR2.024 for lysine and tabtoxinine-beta-lactam biosynthesis.

Overproduction of (S)-lysine in plants is currently carried out through the expression of a feedback insensitive DHDPS enzyme, such as that from Corynebacterium glutamicum. An increased understanding of how plant DHDPS is inhibited by (S)-lysine opens the potential for the generation of a lysine insensitive plant variant for use in improved crop quality. At-DHDPS2 is tightly regulated through inhibition by very low concentrations of (S)-lysine, the end product of the pathway. However, unlike a previous study of the Ns-DHDPS enzyme that observed changes in the orientation of the subunits upon binding of (S)-lysine, X-ray crystallographic and small angle X-ray scattering studies showed that no large structural changes occurred upon binding of (S)-lysine to the allosteric site of At-DHDPS2. Indeed, the changes observed in the lysine bound crystal structure compared to the unliganded structure are confined to residues of the lysine binding pocket itself. The side chain of Trp116 undergoes a shift in rotamer upon lysine binding, closing down against the side chain of the bound lysine in a gate like action. Small rearrangements of the Glu147, His119, Ile120 and Arg146 side chains to accommodate the lysine molecule were also observed. However, these changes in side chain configurations were not propagated to other regions of the structure. We note that the resolution of the structures presented here (2.0–2.2 A) is considerably higher than that of the Ns-DHDPS structures previously published (∼2.8 A) . Since the lysine binding sites of At-DHDPS2 are not situated close to crystal contacts, crystal packing arguments should not preclude observation of structural changes around this site. As such, we would expect to detect any significant conformational changes in the structure due to lysine binding.

The enzymology of lysine biosynthesis in higher plants.

From the practical point of view, this work, in addition to our previous analyses of the vitamin-specific regulons (–), demonstrate one more example of the power of comparative genomics for the functional gene annotation. Comparative analysis of pathway-specific regulatory sites in bacterial genomes is very effective in this respect. Combination of genomic techniques allowed us to identify candidates for previously missing lysine biosynthetic and transport genes in a variety of bacterial species.

alpha-Aminoadipate pathway for the biosynthesis of lysine in lower eukaryotes.
Biosynthesis of lysine in plants: the putative role of meso-diaminopimelate dehydrogenase.

Protein Lounge: Biosynthesis of Lysine

Outline of pathways of synthesis of nonessential amino acids. Modified from Munro HM (ed.) (1969) Evolution of protein metabolism in mammals. In: , vol. 3, pp. 133–182. New York: Academic Press.

Regulation of enzymes of lysine biosynthesis in Corynebacterium glutamicum.

MetaCyc L-lysine biosynthesis I - BioCyc database …

The biosynthesis of amino acids involves several biochemical pathways in which amino acids are assembled from other precursors. The biosynthesis of amino acids is distinct from that involving lipids or carbohydrates because it includes the use of nitrogen.

Molecular aspects of lysine, threonine, and isoleucine biosynthesis in Corynebacterium glutamicum.

Present knowledge of the biosynthesis of lysine is ..

The synthesis of histidine is long and complex and its pathway is intertwined with nucleic acid biosynthesis (specifically purine). The pathway seems to be universal in all organisms able to synthesize histidine. The first five steps of the pathway take ribose from phosphoribosyl pyrophosphate (PRPP) and transform it into Imadiazoleglycerol phosphate. Once the imadiazole ring is formed, glutamate donates the -amino group and the newly formed amine is oxidized to histidine in the last step of the pathway. Energy is required in the form of ATP (in this case elements of the ATP molecule actually becomes part of the amino acid) and pyrophosphate which is lost from phosphoribosyl pyrophosphate and ATP help drive the reaction.