4W61
Crystal structure of beta-ketoacyl thiolase B (BktB) from Ralstonia eutropha
Summary for 4W61
| Entry DOI | 10.2210/pdb4w61/pdb |
| Related | 4W62 |
| Descriptor | Beta-ketothiolase BktB (2 entities in total) |
| Functional Keywords | beta-ketoacyl thiolase, biosynthetic thiolase, transferase |
| Biological source | Cupriavidus necator (strain ATCC 17699 / H16 / DSM 428 / Stanier 337) (Ralstonia eutropha) |
| Total number of polymer chains | 16 |
| Total formula weight | 689985.81 |
| Authors | Fage, C.D.,Keatinge-Clay, A.T. (deposition date: 2014-08-19, release date: 2015-09-09, Last modification date: 2023-09-27) |
| Primary citation | Fage, C.D.,Meinke, J.L.,Keatinge-Clay, A.T. Coenzyme A-free activity, crystal structure, and rational engineering of a promiscuous beta-ketoacyl thiolase fromRalstonia eutropha. J. Mol. Catal., B Enzym., 121:113-121, 2015 Cited by PubMed Abstract: Thiolases catalyze the formation of carbon-carbon bonds in diverse biosynthetic pathways. The promiscuous β-ketoacyl thiolase B of (BktB) has been utilized in the conversion of Coenzyme A (CoA)-linked precursors such as acetyl-CoA and glycolyl-CoA into β-hydroxy acids, including the pharmaceutically-important 3,4-dihydroxybutyric acid. Such thiolases could serve as powerful carbon-carbon bond-forming biocatalysts if handles less costly than CoA were employable. Here, thiolase activity is demonstrated toward substrates linked to the readily-available CoA mimic, -acetylcysteamine (NAC). BktB was observed to catalyze the retro-Claisen condensation of several β-ketoacyl--NAC substrates, with a preference for 3-oxopentanoyl--NAC over 3-oxobutanoyl-, 3-oxohexanoyl-, and 3-oxoheptanoyl--NAC. A 2.0 Å-resolution crystal structure, in which the asymmetric unit consists of four BktB tetramers, provides insight into acyl group specificity and how it may be engineered. By replacing an active site methionine with an alanine, a mutant possessing significant activity towards α-methyl substituted, NAC-linked substrates was engineered. The ability of BktB and its engineered mutants to utilize NAC-linked substrates will facilitate the biocatalytic synthesis of diketide chiral building blocks from feedstock molecules such as acetate and propionate. PubMed: 26494979DOI: 10.1016/j.molcatb.2015.08.007 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.01 Å) |
Structure validation
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