Selectivity of Pyridone- and Diphenyl Ether-Based Inhibitors for the Yersinia pestis FabV Enoyl-ACP Reductase

Abstract

The enoyl-ACP reductase (ENR) catalyzes the last reaction in the elongation cycle of the bacterial type II fatty acid biosynthesis (FAS-II) pathway. While the FabI ENR is a well validated drug target in organisms such as Mycobacterium tuberculosis and Staphylococcus aureus, alternate ENR isoforms have been discovered in other pathogens including the FabV enzyme that is the sole ENR in Yersinia pestis (ypFabV). Previously, we showed that the prototypical ENR inhibitor triclosan was a poor inhibitor of ypFabV and that inhibitors based on the 2-pyridone scaffold were more potent. These studies were performed with the T276S FabV variant. In the present work, we describe a detailed examination of the mechanism and inhibition of wild-type ypFabV and the T276S variant. The T276S mutation significantly reduces the affinity of diphenyl ether inhibitors for ypFabV (20->100 fold). In addition, while T276S ypFabV generally displays higher affinity for 2-pyridone inhibitors compared to the wild-type enzyme, the 4-pyridone scaffold yields compounds with similar affinity for both wild-type and T276S ypFabV. T276 is located at the N-terminus of the helical substrate-binding loop, and structural studies coupled with site-directed mutagenesis reveal that alterations in this residue modulate the size of the active site portal. Subsequently we were able to probe the mechanism of time-dependent inhibition in this enzyme family by extending the inhibition studies to include P142W ypFabV, a mutation that results in gain of slow-onset inhibition for the 4-pyridone PT156.

Triclosan Is an Aminoglycoside Adjuvant for Eradication of Pseudomonas aeruginosa Biofilms

“…Additional publications support this hypothesis, finding that triclosan is able to cause cell death in an efflux pump mutant, despite the presence of FabV (29). In fact, Neckles and colleagues found that FabV could be inhibited by micromolar concentrations of triclosan and diphenyl ethers (51). In addition, our data suggest that FabI is not the sole target of triclosan, given that the combination remains effective against a FabI-deficient strain (Fig.…”

Advances on Mechanism and Drug Discovery of Type-II Fatty Acid Biosynthesis Pathway

“…FabV 最早在霍乱弧菌中被鉴定出来, 且在鼠疫耶 尔森氏菌中是唯一的烯酰基-ACP 还原酶 [79] . 以水稻黄 单胞菌(Xanthomonas oryzae, Xo) XoFabV 为例, 其和 FabI 都具有 Rossmann 折叠核心, 但它们的聚合形式以 及整体结构有很大的不同: 四聚体进一步稳定.…”

“…此外 XoFabV 的催化基序与 FabI/L 存在差异, 为 Y-X 8 -K [80] . 鼠疫耶尔森氏菌 YpFabV 的关 键氨基酸 T276 位于底物结合环的 N 末端, 通过结构研 究与定点突变相结合表明, 该残基的改变可调节活性位 点门的大小 [79] . 最近, Kim 等 [81] 在土壤基因组中分离到 一种 FabI 的同工酶, 并命名为 FabMG (PDB 号码: 6KI9、 6KIA).…”

“…YpFabV 是鼠疫耶尔森氏菌 中唯一的烯酰-ACP 还原酶. 靶向 YpFabV 的抑制剂主要 分为具有吡啶酮和二苯醚骨架的两类抑制剂 [79] . 其中 化合物 PT173(图 8i)抑制 YpFabV 的机制与三氯生抑制 FabI 的机制相似(图 8h).…”

Crystal Structure of FabV, A New Class of Enoyl‐Acyl Carrier Protein Reductase from Vibrio fischeri

“…As the determination of the first structure of FabV in 2011, considerable efforts have been taken to discover and develop its inhibitors with high activity and greater specificity . The previous report revealed that the FabV inhibitors are developed based on the scaffold of triclosan, where one of the diphenyl ether rings is replaced with a 2‐pyridone .…”