RT Journal Article
SR Electronic
T1 Electron cryomicroscopy observation of acyl carrier protein translocation in type I fungal fatty acid synthase
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 636167
DO 10.1101/636167
A1 Jennifer W. Lou
A1 Kali R. Iyer
A1 S. M. Naimul Hasan
A1 Leah E. Cowen
A1 Mohammad T. Mazhab-Jafari
YR 2019
UL http://biorxiv.org/content/early/2019/05/14/636167.abstract
AB During fatty acid biosynthesis, acyl carrier proteins (ACPs) from type I fungal fatty acid synthase (FAS) shuttle substrates and intermediates within a reaction chamber that hosts multiple spatially-fixed catalytic centers. A major challenge in understanding the mechanism of ACP-mediated substrate shuttling is experimental observation of its transient interaction landscape within the reaction chamber. Here, we have shown that ACP spatial distribution is sensitive to the presence of substrates in a catalytically inhibited state, which enables high-resolution investigation of the ACP-dependent conformational transitions within the enoyl reductase (ER) reaction site. In two fungal FASs with distinct ACP localization, the shuttling domain is targeted to the ketoacyl-synthase (KS) domain and away from other catalytic centers, such as acetyl-transferase (AT) and ER domains by steric blockage of the KS active site followed by addition of substrates. These studies strongly suggest that acylation of phosphopantetheine arm of ACP may be an integral part of the substrate shuttling mechanism in type I fungal FAS.