▪ Abstract The increase in drug-resistant pathogenic bacteria has created an urgent demand for new antibiotics. Among the more attractive targets for the development of new antibacterial compounds are the enzymes of fatty acid biosynthesis. Although a number of potent inhibitors of microbial fatty acid biosynthesis have been discovered, few of these are clinically useful drugs. Several of these fatty acid biosynthesis inhibitors have potential as lead compounds in the development of new antibacterials. This review encompasses the known inhibitors and prospective targets for new antibacterials.

Bacterial Fatty Acid Biosynthesis: Targets for Antibacterial Drug Discovery

Lipid biosynthesis as a target for antibacterial agents.

Recent advances in the biochemistry and molecular biology of fatty acyl desaturases.

Many plants deposit TAG in seeds and fruits as the major form of storage lipid. TAG production is of tremendous socioeconomic value in food, nutraceutical, and industrial applications, and thus numerous conventional and molecular genetic strategies have been explored in attempts to increase TAG content and modify the FA composition of plant seed oils. Much research has focused on the acyl-CoA-dependent reaction catalyzed by diacylglycerol acyltransferase (DGAT), which is an integral endoplasmic reticulum protein and has also been shown to be present in oil bodies and plastids. DGAT enzymes exhibit diverse biochemical properties among different plant species, many of which are summarized here. In addition to catalyzing a critical step in TAG biosynthesis, there is evidence that DGAT has roles in lipid metabolism associated with germination and leaf senescence. TAG can also be formed in plants via two different acyl-CoA-independent pathways, catalyzed by phospholipid: diacylglycerol acyltransferase and diacylglycerol transacylase. The current understanding of the terminal step in TAG formation in plants and the development of molecular genetic approaches aimed at altering TAG yield and FA composition of TAG are discussed.

Diacylglycerol acyltransferase: a key mediator of plant triacylglycerol synthesis.

Inhibition of beta-ketoacyl-acyl carrier protein synthases by thiolactomycin and cerulenin. Structure and mechanism.

The type II fatty acid synthases (FASs) of higher plants (and Escherichia coli) contain three condensing enzymes called beta-ketoacyl-ACP synthases (KAS), where ACP is acyl-carrier-protein. We have used novel derivatives of the antibiotic thiolactomycin to inhibit these enzymes. Overall de novo fatty acid biosynthesis was measured using [1-(14)C]acetate substrate and chloroplast preparations from pea leaves, and [1-(14)C]laurate was used to distinguish between the effects of the inhibitors on KAS I from those on KAS II. In addition, the activities of these enzymes, together with the short-chain condensing enzyme, KAS III, were measured directly. Six analogues were tested and two, both with extended hydrocarbon side chains, were found to be more effective inhibitors than thiolactomycin. Incubations with chloroplasts and direct assay of the individual condensing enzymes showed that all three compounds inhibited the pea FAS condensing enzymes in the order KAS II > KAS I > KAS III. These results demonstrate the general activity of thiolactomycin and its derivatives against these FAS condensation reactions, and suggest that such compounds will be useful for further detailed studies of inhibition and for use as pharmaceuticals against Type II FASs of pathogens.

/pdf/novel-inhibitors-of-the-condensing-enzymes-of-the-type-ii-1zud88u9gu.pdf

Novel inhibitors of the condensing enzymes of the type II fatty acid synthase of pea (Pisum sativum)

Aims: To develop rapid means of distinguishing between cysts and trophozoites of the opportunistic pathogen, Acanthamoeba castellanii, the causative agent of keratitis.
Methods and Results: Fluorescence of Congo Red, Calcoflor White was specific for the endocyst wall; trophozoites did not become fluorescent. The anionic oxonol dye, DiBAC4(3), did not penetrate the cytoplasmic membrane after short-term (<5 min) exposure, whereas cysts are permeable and become fluorescent. Confocal scanning laser microscopy confirmed these properties and large populations of organisms were analysed by flow cytometry.
Conclusions: These data provide a rapid alternative to traditional haemocytometer or plate counts for discrimination of trophozoites from cysts.
Significance and Impact of the Study: Rapid and precise determination of the growth cycle of a dangerous ocular pathogen.

https://sfamjournals.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-2672.2001.01296.x

Encystation of Acanthamoeba castellanii: dye uptake for assessment by flow cytometry and confocal laser scanning microscopy.

Glycerolipid synthesis by microsomal fractions from Olea europaea fruits and tissue cultures

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/S0014-5793%2898%2900218-X

Oxygen induces fatty acid (n‐6)‐desaturation independently of temperature in Acanthamoeba castellanii

Induction of fatty acid desaturation is very important for the temperature adaptation of poikilotherms. However, in oxygen-limited late-exponential-phase Acanthamoeba castellanii cultures, oxygen alone was able to induce increased activity of a fatty acid desaturase that converts oleate into linoleate and which has been implicated in the temperature adaptation of this organism. Experiments with [Delta]10-nonadecenoate showed that the enzyme is an n-6 desaturase rather than a [Delta]12-desaturase. It also used preferentially 1-acyl-2-oleoyl-phosphatidylcholine as substrate and NAD(P)H as electron donor. The involvement of cytochrome b5 as an intermediate electron carrier was shown by difference spectra measurements and anti-(cytochrome b5) antibody experiments. Of the three protein components of the desaturase complex, oxygen only increased the activity of the terminal (cyanide-sensitive) protein during n-6 desaturase induction. The induction of this terminal protein paralleled well the increase in overall oleate n-6 desaturation. The ability of oxygen to induce oleate desaturase independently of temperature in this lower eukaryotic animal model is of novel intrinsic interest, as well as being important for the design of future experiments to determine the molecular mechanism of temperature adaptation in poikilotherms.

/pdf/oxygen-induction-of-a-novel-fatty-acid-n-6-desaturase-in-the-4zc17gs306.pdf

Andrew J. Rutter

Papers

Novel inhibitors of the condensing enzymes of the type II fatty acid synthase of pea (Pisum sativum)

Encystation of Acanthamoeba castellanii: dye uptake for assessment by flow cytometry and confocal laser scanning microscopy.

Glycerolipid synthesis by microsomal fractions from Olea europaea fruits and tissue cultures

Oxygen induces fatty acid (n‐6)‐desaturation independently of temperature in Acanthamoeba castellanii

Oxygen induction of a novel fatty acid n-6 desaturase in the soil protozoon, Acanthamoeba castellanii.