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Publication Abstract from PubMed

Neisseria meningitidis 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (NmeDAH7PS) adopts a homotetrameric structure consisting of an extensive and a less extensive interface. Perturbation of the less extensive interface through a single mutation of a salt bridge (Arg126-Glu27) formed at the tetramer interface of all chains resulted in a dimeric DAH7PS in solution, as determined by small angle X-ray scattering, analytical ultracentrifugation and analytical size-exclusion chromatography. The dimeric NmeDAH7PSR126S variant was shown to be catalytically active in the aldol-like condensation reaction between d-erythrose 4-phosphate and phosphoenolpyruvate, and allosterically inhibited by l-phenylalanine to the same extent as the wild-type enzyme. The dimeric NmeDAH7PSR126S variant exhibited a slight reduction in thermal stability by differential scanning calorimetry experiments and a slow loss of activity over time compared to the wild-type enzyme. Although NmeDAH7PSR126S crystallised as a tetramer, like the wild-type enzyme, structural asymmetry at the less extensive interface was observed consistent with its destabilisation. The tetrameric association enabled by this Arg126-Glu27 salt-bridge appears to contribute solely to the stability of the protein, ultimately revealing that the functional unit of NmeDAH7PS is dimeric.

The Functional Unit of Neisseria meningitidis 3-Deoxy--Arabino-Heptulosonate 7-Phosphate Synthase Is Dimeric.,Cross PJ, Heyes LC, Zhang S, Nazmi AR, Parker EJ PLoS One. 2016 Feb 1;11(2):e0145187. doi: 10.1371/journal.pone.0145187., eCollection 2016. PMID:26828675^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.