3c0j
Structure of E. coli dihydrodipicolinate synthase complexed with hydroxypyruvate
Structural highlights
FunctionDAPA_ECOLI Catalyzes the condensation of (S)-aspartate-beta-semialdehyde [(S)-ASA] and pyruvate to 4-hydroxy-tetrahydrodipicolinate (HTPA).[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedIn recent years, dihydrodipicolinate synthase (DHDPS, E.C. 4.2.1.52) has received considerable attention from a mechanistic and structural viewpoint. DHDPS catalyzes the reaction of (S)-aspartate-beta-semialdehyde with pyruvate, which is bound via a Schiff base to a conserved active-site lysine (Lys161 in the enzyme from Escherichia coli). To probe the mechanism of DHDPS, we have studied the inhibition of E. coli DHDPS by the substrate analog, beta-hydroxypyruvate. The K (i) was determined to be 0.21 (+/-0.02) mM, similar to that of the allosteric inhibitor, (S)-lysine, and beta-hydroxypyruvate was observed to cause time-dependent inhibition. The inhibitory reaction with beta-hydroxypyruvate could be qualitatively followed by mass spectrometry, which showed initial noncovalent adduct formation, followed by the slow formation of the covalent adduct. It is unclear whether beta-hydroxypyruvate plays a role in regulating the biosynthesis of meso-diaminopimelate and (S)-lysine in E. coli, although we note that it is present in vivo. The crystal structure of DHDPS complexed with beta-hydroxypyruvate was solved. The active site clearly showed the presence of the inhibitor covalently bound to the Lys161. Interestingly, the hydroxyl group of beta-hydroxypyruvate was hydrogen-bonded to the main-chain carbonyl of Ile203. This provides insight into the possible catalytic role played by this peptide unit, which has a highly strained torsion angle (omega approximately 201 degrees ). A survey of the known DHDPS structures from other organisms shows this distortion to be a highly conserved feature of the DHDPS active site, and we propose that this peptide unit plays a critical role in catalysis. Conserved main-chain peptide distortions: a proposed role for Ile203 in catalysis by dihydrodipicolinate synthase.,Dobson RC, Griffin MD, Devenish SR, Pearce FG, Hutton CA, Gerrard JA, Jameson GB, Perugini MA Protein Sci. 2008 Dec;17(12):2080-90. Epub 2008 Sep 11. PMID:18787203[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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