4NZS
Crystal structure of beta-ketothiolase BktB B from Ralstonia eutropha H16
Summary for 4NZS
| Entry DOI | 10.2210/pdb4nzs/pdb |
| Descriptor | Beta-ketothiolase BktB (2 entities in total) |
| Functional Keywords | thiolase superfamily, transferase |
| Biological source | Ralstonia eutropha |
| Total number of polymer chains | 2 |
| Total formula weight | 83300.86 |
| Authors | |
| Primary citation | Kim, E.J.,Son, H.F.,Kim, S.,Ahn, J.W.,Kim, K.J. Crystal structure and biochemical characterization of beta-keto thiolase B from polyhydroxyalkanoate-producing bacterium Ralstonia eutropha H16 Biochem.Biophys.Res.Commun., 444:365-369, 2014 Cited by PubMed Abstract: ReBktB is a β-keto thiolase from Ralstonia eutropha H16 that catalyzes condensation reactions between acetyl-CoA with acyl-CoA molecules that contains different numbers of carbon atoms, such as acetyl-CoA, propionyl-CoA, and butyryl-CoA, to produce valuable bioproducts, such as polyhydroxybutyrate, polyhydroxybutyrate-hydroxyvalerate, and hexanoate. We solved a crystal structure of ReBktB at 2.3Å, and the overall structure has a similar fold to that of type II biosynthetic thiolases, such as PhbA from Zoogloea ramigera (ZrPhbA). The superposition of this structure with that of ZrPhbA complexed with CoA revealed the residues that comprise the catalytic and substrate binding sites of ReBktB. The catalytic site of ReBktB contains three conserved residues, Cys90, His350, and Cys380, which may function as a covalent nucleophile, a general base, and second nucleophile, respectively. For substrate binding, ReBktB stabilized the ADP moiety of CoA in a distinct way compared to ZrPhbA with His219, Arg221, and Asp228 residues, whereas the stabilization of β-mercaptoethyamine and pantothenic acid moieties of CoA was quite similar between these two enzymes. Kinetic study of ReBktB revealed that K(m), V(max), and K(cat) values of 11.58 μM, 1.5 μmol/min, and 102.18 s(-1), respectively, and the catalytic and substrate binding sites of ReBktB were further confirmed by site-directed mutagenesis experiments. PubMed: 24462871DOI: 10.1016/j.bbrc.2014.01.055 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.29 Å) |
Structure validation
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