Structural elements that govern Sec14-like PITP sensitivities to potent small molecule inhibitors

Abstract

This article is available online at http://www.jlr.org Phosphoinositides (PIPs) are phosphorylated derivatives of phosphatidylinositol (PtdIns), and the metabolism of these lipids constitutes a major membrane-associated signaling system in eukaryotic cells (1)(2)(3)(4)(5). The chemical heterogeneity that distinguishes individual PIP species forms one basis for functionally compartmentalizing signaling platform identities on membrane surfaces ( 6, 7 ). Yet while the chemical heterogeneity of PIP species is simple, it translates to an enormous diversity of biological outcomes that derive from PIP signaling. In that regard, recent studies demonstrate additional layers of functional specifi cation for PIP signaling that are of such resolution that production of an individual PIP species by a specifi c PtdIns kinase yields multiple biological outcomes in the same cell ( 8 ). We now appreciate that PtdIns transfer proteins (PITPs) play critical roles in functional compartmentalization of PIP signaling reactions by channeling PtdIns to PtdIns kinases and, subsequently, to distinct sets of effector proteins ( 9-11 ). The Sec14-like PITPs are best studied in this regard, and the multiplicity of Sec14-like PITPs expressed in even simple unicellular eukaryotes highlights the high degree of functional specifi cation for these proteins ( 12,13 ).Emerging evidence that PITPs instruct the biological outcomes of PtdIns kinase activities recommends these proteins as novel targets for chemical intervention with PIP signaling pathways in cells ( 11,14 ). The advantages of targeting PITPs for this purpose are that such interventions can be imposed with selectivities superior to those possible by popular strategies that either target individual PtdIns-kinase isoforms or individual PIP species ( 15,16 ). Proof of concept is exemplifi ed by the identifi cation and validation of several classes of small molecule inhibitors (SMIs) that target Sec14, the major PITP of yeast. Abbreviations: MM-GBSA, molecular mechanics with generalized born and surface area; NPPM, nitrophenyl(4-(2-methoxyphenyl)piperazin-1-yl)methanone; PDB, Protein Data Bank; PIP, phosphoinositide; PITP, phosphatidylinositol transfer protein; PtdCho, phosphatidylcholine; PtdIns, phosphatidylinositol; SMI, small molecule inhibitor .

High-Resolution Genetics Identifies the Lipid Transfer Protein Sec14p as Target for Antifungal Ergolines

“…cerevisisae (PDB ID: 1AUA) and human (PDB ID: 1OLM) have been solved. Although the lipid-binding pocket of the enzyme is well characterized [35–37] Sec14p has not been crystalized when bound to phosphatidylethanolamine (PtdEtn) substrate. The crystal structure of the S. cerevisisae Sfh1protein (PDB ID: 3B7Q), sharing 62.3% identity with Sec14p, shows that phosphatidylcoline (PC) hydrophobic tail forms van der Waals interactions with a cluster of hydrophobic residues, whereas the phosphate moiety is interacting with the side-chain hydroxyl groups of residues S175 and T177, and the nitrogen contacts the phenolic oxygen of Y113 (Fig 3A).…”

“…Crystal structures of Sec14 proteins from various species, including S . cerevisiae [55], have been solved and the lipid-binding pocket of the enzyme is well characterized [35–37]. The residues S173 and T175 are involved in the coordination of the phosphate moiety whereas the phenolic oxygen of Y111 binds the nitrogen the substrate PtdEtn.…”

Non-vesicular Lipid Transport Machinery in Entamoeba histolytica

“…Once E. histolytica -specific LTPs and lipid transfer mechanisms are identified, they may potentially provide a novel drug target against this medically important parasite. Since most of existent chemical interventions against lipid signaling pathways target particular lipid metabolizing enzymes (Nile et al, 2014 ; Khan et al, 2016 ), such intervention often exerts specific and limited overall effects to the eukaryotic cells, e.g., cancer cells. In addition, parasitic organisms often have highly adaptable nature and a bypass mechanism to overcome the effects caused by various chemical insults, results in the generation of drug resistance.…”

A Sec14-like phosphatidylinositol transfer protein paralog defines a novel class of heme-binding proteins

“…The identities of all constructions were confirmed by DNA sequencing (Eton). Genetic methods and media used were previously described ( Kearns et al, 1998 ; Khan et al, 2016 ).…”