5vbx

Publication Abstract from PubMed

The Escherichia coli holo-(acyl carrier protein) synthase (ACPS) catalyzes the coenzyme A-dependent activation of apo-ACPP to generate holo-(acyl carrier protein) (holo-ACPP) in an early step of fatty acid biosynthesis. E. coli ACPS is sufficiently different from the human fatty acid synthase to justify the development of novel ACPS-targeting antibiotics. Models of E. coli ACPS in unliganded and holo-ACPP-bound forms solved by X-ray crystallography to 2.05A and 4.10A, respectively, revealed ACPS bound three product holo-ACPP molecules to form a 3:3 hexamer. Solution NMR spectroscopy experiments validated the ACPS binding interface on holo-ACPP using chemical shift perturbations and by determining the relative orientation of holo-ACPP to ACPS by fitting residual dipolar couplings. The binding interface is organized to arrange contacts between positively charged ACPS residues and the holo-ACPP phosphopantetheine moiety, indicating product contains more stabilizing interactions than expected in the enzyme:substrate complex. Indeed, holo-ACPP bound the enzyme with greater affinity than the substrate, apo-ACPP, and with negative cooperativity. The first equivalent of holo-ACPP bound with a KD=62+/-13nM, followed by the binding of two more equivalents of holo-ACPP with KD=1.2+/-0.2muM. Cooperativity was not observed for apo-ACPP which bound with KD=2.4+/-0.1muM. Strong product binding and high levels of holo-ACPP in the cell identify a potential regulatory role of ACPS in fatty acid biosynthesis.

Structure, high affinity and negative cooperativity of the Escherichia coli holo-(acyl carrier protein):holo-(acyl carrier protein) synthase complex.,Marcella AM, Culbertson SJ, Shogren-Knaak MA, Barb AW J Mol Biol. 2017 Oct 17. pii: S0022-2836(17)30497-7. doi:, 10.1016/j.jmb.2017.10.015. PMID:29054754^[2]

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