9NG1
Crystal structure of FabG4 from Pseudomonas putida KT2440
Summary for 9NG1
| Entry DOI | 10.2210/pdb9ng1/pdb |
| Descriptor | 2,3-dihydroxy-2,3-dihydro-p-cumate dehydrogenase (2 entities in total) |
| Functional Keywords | fatty acid synthase, polyketide synthase, acyl carrier protein, oxidoreductase |
| Biological source | Pseudomonas putida |
| Total number of polymer chains | 4 |
| Total formula weight | 114050.89 |
| Authors | Andrzejewski, S.J.,Friedman, A.J.,Mains, K.,Thompson, A.,Sankaran, B.,Zwart, P.H.,Shirts, M.R.,Fox, J.M. (deposition date: 2025-02-21, release date: 2026-05-20) |
| Primary citation | Andrzejewski, S.J.,Friedman, A.J.,Mains, K.,Thompson, A.,Hamel, N.L.,Sankaran, B.,Zwart, P.H.,Shirts, M.R.,Fox, J.M. Protein-Protein Complex Stability Controls Substrate Scope in a beta-Ketoacyl-ACP Reductase Specific for Medium Chains. Angew.Chem.Int.Ed.Engl., 64:e202508316-e202508316, 2025 Cited by PubMed Abstract: Assembly-line enzymes carry out multistep synthesis of important metabolites by using acyl carrier proteins (ACPs) to shuttle intermediates along defined sequences of active sites. Despite longstanding interest in reprogramming these systems for metabolic engineering and biosynthetic chemistry, the mechanisms underlying their reaction order remain poorly understood and difficult to control. Here we describe a β-ketoacyl-ACP reductase from Pseudomonas putida (PpFabG4) with an unusual selectivity for medium chains and use it to explore the molecular basis of substrate specificity in enzymes that pull intermediates from fatty acid synthesis, a common route to specialized products. X-ray crystallography shows no obvious barriers to short-chain binding. Molecular simulations and supporting mutational analyses indicate that substrate preference arises instead from a weak enzyme-ACP interaction that is stabilized by medium acyl chains but not by short chains. Indeed, mutations that strengthen this interaction for PpFabG4 or weaken it for EcFabG, an Escherichia coli β-ketoacyl-ACP reductase with a broad substrate specificity, can enhance or reduce activity on short-chain substrates by over 100-fold. Our findings show how the stability of enzyme-ACP interactions can control substrate scope in promiscuous enzymes and guide the exchange of intermediates between (and within) assembly-line systems. PubMed: 40891111DOI: 10.1002/anie.202508316 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.91 Å) |
Structure validation
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