A human fatty acid synthase inhibitor binds β-ketoacyl reductase in the keto-substrate site

Abstract

Human fatty acid synthase (hFAS) is a complex, multifunctional enzyme that is solely responsible for the de novo synthesis of long chain fatty acids. hFAS is highly expressed in a number of cancers, with low expression observed in most normal tissues. Although normal tissues tend to obtain fatty acids from the diet, tumor tissues rely on de novo fatty acid synthesis, making hFAS an attractive metabolic target for the treatment of cancer. We describe here the identification of GSK2194069, a potent and specific inhibitor of the β-ketoacyl reductase (KR) activity of hFAS; the characterization of its enzymatic and cellular mechanism of action; and its inhibition of human tumor cell growth. We also present the design of a new protein construct suitable for crystallography, which resulted in what is to our knowledge the first co-crystal structure of the human KR domain and includes a bound inhibitor.

Functional and Structural Analysis of Programmed C-Methylation in the Biosynthesis of the Fungal Polyketide Citrinin

“…The closest structural homologs are the SAM-dependent methyltransferase from Aquifex aeolicus (unpublished, PDB:3DH0), the methyltransferase domain of bacterial-AvHen1-CN (PDB: 3JWJ), a putative methyltransferase from Sulfolobus solfataricus (unpublished, PDB: 3I9F), NodS from Bradyrhizobium japonicum WM9 (PDB: 3OFK) and the methyltransferase domain of bacterial-CtHen1-C (PDB: 3JWG) with a C α rmsd of 2.0–2.4 Å and 160–195 aligned residues. The catalytically inactive pseudo-methyltransferase (ψCMeT) of the human fatty acid synthase (FAS) aligns with a C α rmsd of 2.5 Å (158 aligned aa) (Hardwicke et al, 2014) and is the closest structural homolog in carrier protein-dependent multienzymes. The C -terminal subdomain integrates into the N -terminal subdomain through a region around helix 15 that forms the base of the ligand binding tunnel, resembling an open palm (“palm helix region”), and is structurally conserved in mammalian FAS (Hardwicke et al, 2014; Maier et al, 2008), but deleted in insect FAS and some highly reducing-PKSs (HR-PKS) (Figure S3).…”

“…The catalytically inactive pseudo-methyltransferase (ψCMeT) of the human fatty acid synthase (FAS) aligns with a C α rmsd of 2.5 Å (158 aligned aa) (Hardwicke et al, 2014) and is the closest structural homolog in carrier protein-dependent multienzymes. The C -terminal subdomain integrates into the N -terminal subdomain through a region around helix 15 that forms the base of the ligand binding tunnel, resembling an open palm (“palm helix region”), and is structurally conserved in mammalian FAS (Hardwicke et al, 2014; Maier et al, 2008), but deleted in insect FAS and some highly reducing-PKSs (HR-PKS) (Figure S3). …”

“…Such N -terminal subdomains of Class I methyltransferases that cap the SAH/SAM-binding pocket often serve a role in acceptor substrate selection (Peng et al, 2011). In the related mammalian FAS multienzymes, which comprise catalytically inactive ΨCMeTs domains and provide the only structural depiction of CMeT integration into a multienzyme, this region is considerably truncated and disordered (Hardwicke et al, 2014; Maier et al, 2008). Nevertheless, the N -terminal CMeT subdomains in FASs reveal helices at equivalent positions to helix 4, 7 and 9/10 with a C α rmsd of 2.5 Å over 42 aligned aa, indicating a common evolutionary origin (Figure S4A).…”

Molecular Pathways: Fatty Acid Synthase

“…None of these compounds have been tested in cancer patients due to limitations imparted by their pharmacologic properties or sideeffect profiles that would limit their clinical development. A new generation of molecules such as GSK2194069 (26), JNJ-54302833 (27), IPI-9119 (28), and TVB-2640 (29) are in development, but only TVB-2640 has moved into the clinic.…”

Targeting Lipid Metabolic Reprogramming as Anticancer Therapeutics

“…However, orlistat has a poor solubility and oral bioavailability, thereby its clinical application for systemic use in cancer treatment is limited 41. In addition, an antimicrobial agent triclosan42 and GSK219406943 have been shown to have a potent inhibitory activity in FASN. Recently, Alwarawrah et al44 showed that Fasnall, a novel thiophenopyrimidine-based FASN inhibitor, exerts potent antitumor activity against various breast cancer cell lines and is well tolerated in mice.…”