10.17863/CAM.11087
Vance, S
Tkachenko, O
Thomas, B
Bassuni, M
Hong, Hui
Nietlispach, Daniel
0000-0003-4364-9291
Broadhurst, Richard
0000-0002-0264-4593
Sticky swinging arm dynamics: studies of an acyl carrier protein domain from the mycolactone polyketide synthase
Apollo - University of Cambridge Repository (staging)
2016
4’-phosphopantetheine
acyl carrier protein
NMR
type I polyketide synthase
mycolactone
Apollo - University of Cambridge Repository (staging)
Apollo - University of Cambridge Repository (staging)
2016-04-15
Article
0264-6021
1470-8728
Attribution 4.0 International
Type I modular polyketide synthases (PKSs) produce polyketide natural products by passing a growing acyl substrate chain between a series of enzyme domains housed within a gigantic multifunctional polypeptide assembly. Throughout each round of chain extension and modification reactions, the substrate stays covalently linked to an acyl carrier protein (ACP) domain. Here we report on the solution structure and dynamics of an ACP domain excised from MLSA2, module 9 of the PKS system that constructs the macrolactone ring of the toxin mycolactone, cause of the tropical disease Buruli ulcer. After modification of apo ACP with 4’-phosphopantetheine (Ppant) to create the holo form, 15N nuclear spin relaxation and paramagnetic relaxation enhancement experiments suggest that the prosthetic group swings freely. The minimal chemical shift perturbations displayed by Ppant-attached C3 and C4 acyl chains imply that these substrate-mimics remain exposed to solvent at the end of a flexible Ppant arm. By contrast, hexanoyl and octanoyl chains yield much larger chemical shift perturbations, indicating that they interact with the surface of the domain. The solution structure of octanoyl-ACP shows the Ppant arm bending to allow the acyl chain to nestle into a nonpolar pocket, while the prosthetic group itself remains largely solvent exposed. Although the highly reduced octanoyl group is not a natural substrate for the ACP from MLSA2, similar presentation modes would permit partner enzyme domains to recognize an acyl group while it is bound to the surface of its carrier protein, allowing simultaneous interactions with both the substrate and the ACP.
This work was supported by the Wellcome Trust, grant number 094252/Z/10/Z. MB holds a research studentship funded by the Yousef Jameel Academic Foundation and the Cambridge Trust.
This is the final version of the article. It first appeared from Portland Press via https://doi.org/10.1042/BCJ20160041