Exploring the Mechanism of Acyl Carrier Protein Interactions and Acyl Transfer

Abstract

As an essential protein in bacterial fatty acid synthesis, acyl carrier protein (ACP) is an attractive anti‐microbial drug target. The three‐dimensional structure of ACP is comprised of three main parallel α–helices, which create a hydrophobic binding pocket that encloses a fatty acyl chain when attached. ACP interacts with most partner enzymes through the acidic helix II, but the exact mechanism of interaction and acyl transfer to a partner enzyme is poorly understood. For acyl transfer to occur, we hypothesize that a conformational change is required. To examine this requirement, we have analyzed a cyclic version of Vibrio harveyi ACP created by split‐intein technology (Volkmann, et al. (2010) JBC 285: 8605) using molecular dynamics, mass spectrometry, tryptophan fluorescence, and other biophysical techniques. We have demonstrated that cyclic ACP is more thermodynamically stable than wild‐type linear ACP. Furthermore, we show that cyclic ACP is able to act as a substrate for holo‐ACP synthase, yielding a cyclic ACP capable of carrying fatty acids. (Supported by NSERC and an NSHRF Student Research Award)