5onn
Crystal Structure of Ectoine Synthase from P. lautus
Structural highlights
FunctionA0A2A5LBI6_PAELA Catalyzes the circularization of gamma-N-acetyl-alpha,gamma-diaminobutyric acid (ADABA) to ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidine carboxylic acid), which is an excellent osmoprotectant.[HAMAP-Rule:MF_01255] Publication Abstract from PubMedEctoine synthase (EctC) is the signature enzyme for the production of ectoine, a compatible solute and chemical chaperone widely synthesized by bacteria as a cellular defense against the detrimental effects of osmotic stress. EctC catalyzes the last step in ectoine synthesis through cyclo-condensation of the EctA-formed substrate N-gamma-acetyl-L-2,4-diaminobutyric acid via a water elimination reaction. We have biochemically and structurally characterized the EctC enzyme from the thermo-tolerant bacterium Paenibacillus lautus (Pl). EctC is a member of the cupin superfamily and forms dimers, both in solution and in crystals. We obtained high-resolution crystal structures of the (Pl)EctC protein in forms that contain (i) the catalytically important iron, (ii) iron and the substrate N-gamma-acetyl-L-2,4-diaminobutyric acid, and (iii) iron and the enzyme reaction product ectoine. These crystal structures lay the framework for a proposal for the EctC-mediated water-elimination reaction mechanism. Residues involved in coordinating the metal, the substrate, or the product within the active site of ectoine synthase are highly conserved among a large group of EctC-type proteins. Collectively, the biochemical, mutational, and structural data reported here yielded detailed insight into the structure-function relationship of the (Pl)EctC enzyme and are relevant for a deeper understanding of the ectoine synthase family as a whole. Illuminating the catalytic core of ectoine synthase through structural and biochemical analysis.,Czech L, Hoppner A, Kobus S, Seubert A, Riclea R, Dickschat JS, Heider J, Smits SHJ, Bremer E Sci Rep. 2019 Jan 23;9(1):364. doi: 10.1038/s41598-018-36247-w. PMID:30674920[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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