| Title | Characterisation of the first enzymes committed to lysine biosynthesis in Arabidopsis thaliana |
| Publication Type | Journal Article |
| Year of Publication | 2012 |
| Authors | Griffin, M.D.W., Billakanti J.M., Wason A., Keller S., Mertens H.D.T., Atkinson S.C., Dobson R.C.J., Perugini M.A., Gerrard J.A., and Pearce F.G. |
| Journal | PLoS ONE |
| Volume | 7 |
| Issue | 7 |
| Date Published | 2012 |
| ISSN | 19326203 (ISSN) |
| Keywords | Allosteric Site, amino acid synthesis, Arabidopsis, Arabidopsis Proteins, Arabidopsis thaliana, article, Bacteria (microorganisms), bacterial enzyme, binding site, Biosynthetic Pathways, controlled study, crystal structure, Crystallography, X-Ray, dihydrodipicolinate reductase, dihydrodipicolinate reductase 2, dihydrodipicolinate synthase, dihydrodipicolinate synthase 2, dimerization, enzyme activity, enzyme binding, enzyme inhibition, enzyme kinetics, enzyme specificity, enzyme structure, enzyme substrate, Hydro-Lyases, Kinetics, Light, lysine, Models, Molecular, nonhuman, oxidoreductase, Protein Interaction Domains and Motifs, Protein Structure, Quaternary, radiation scattering, reduced nicotinamide adenine dinucleotide, reduced nicotinamide adenine dinucleotide phosphate, Scattering, Small Angle, Structural Homology, Protein, structure analysis, ultracentrifugation, unclassified drug |
| Abstract | In plants, the lysine biosynthetic pathway is an attractive target for both the development of herbicides and increasing the nutritional value of crops given that lysine is a limiting amino acid in cereals. Dihydrodipicolinate synthase (DHDPS) and dihydrodipicolinate reductase (DHDPR) catalyse the first two committed steps of lysine biosynthesis. Here, we carry out for the first time a comprehensive characterisation of the structure and activity of both DHDPS and DHDPR from Arabidopsis thaliana. The A. thaliana DHDPS enzyme (At-DHDPS2) has similar activity to the bacterial form of the enzyme, but is more strongly allosterically inhibited by (S)-lysine. Structural studies of At-DHDPS2 show (S)-lysine bound at a cleft between two monomers, highlighting the allosteric site; however, unlike previous studies, binding is not accompanied by conformational changes, suggesting that binding may cause changes in protein dynamics rather than large conformation changes. DHDPR from A. thaliana (At-DHDPR2) has similar specificity for both NADH and NADPH during catalysis, and has tighter binding of substrate than has previously been reported. While all known bacterial DHDPR enzymes have a tetrameric structure, analytical ultracentrifugation, and scattering data unequivocally show that At-DHDPR2 exists as a dimer in solution. The exact arrangement of the dimeric protein is as yet unknown, but ab initio modelling of x-ray scattering data is consistent with an elongated structure in solution, which does not correspond to any of the possible dimeric pairings observed in the X-ray crystal structure of DHDPR from other organisms. This increased knowledge of the structure and function of plant lysine biosynthetic enzymes will aid future work aimed at improving primary production. © 2012 Griffin et al. |
| URL | http://www.scopus.com/inward/record.url?eid=2-s2.0-84863615811&partnerID=40&md5=5955668222fc9d818abcc36b4dfccc32 |
| DOI | 10.1371/journal.pone.0040318 |
