Checks and balances in membrane phospholipid class and acyl chain homeostasis, the yeast perspective

Abstract

Glycerophospholipids are the most abundant membrane lipid constituents in most eukaryotic cells. As a consequence, phospholipid class and acyl chain homeostasis are crucial for maintaining optimal physical properties of membranes that in turn are crucial for membrane function. The topic of this review is our current understanding of membrane phospholipid homeostasis in the reference eukaryote Saccharomyces cerevisiae. After introducing the physical parameters of the membrane that are kept in optimal range, the properties of the major membrane phospholipids and their contributions to membrane structure and dynamics are summarized. Phospholipid metabolism and known mechanisms of regulation are discussed, including potential sensors for monitoring membrane physical properties. Special attention is paid to processes that maintain the phospholipid class specific molecular species profiles, and to the interplay between phospholipid class and acyl chain composition when yeast membrane lipid homeostasis is challenged. Based on the reviewed studies, molecular species selectivity of the lipid metabolic enzymes, and mass action in acyl-CoA metabolism are put forward as important intrinsic contributors to membrane lipid homeostasis.

Regulation of Gene Expression through a Transcriptional Repressor that Senses Acyl-Chain Length in Membrane Phospholipids

“…Whereas mechanisms controlling the level of FA desaturation in response to ambient temperature and membrane fluidity have been described in detail, much less is known about the mechanisms regulating chain length distribution (de Kroon et al., 2013). In addition to their fundamental roles as components of biological membranes, FAs also serve essential functions as energy substrates, signaling molecules, or protein modifiers.…”

“…Furthermore, gradual increase in chain length and, subsequently, membrane thickness along the secretory pathway is an important determinant and provides sufficient differentiation for protein sorting (Bretscher and Munro, 1993). Similar to mammalian cells, yeast membranes predominantly consist of mono- and di-unsaturated PLs containing C16 and C18 acyl-chains to maintain the liquid crystalline state at physiological temperature (de Kroon et al., 2013). A decrease in the ambient temperature primarily triggers an increase in the C16/C18 ratio rather than a change in the degree of acyl-chain desaturation (Martin et al., 2007).…”

Unremodeled and Remodeled Cardiolipin Are Functionally Indistinguishable in Yeast

“…Despite limited acyl chain specificity of the CL biosynthetic enzymes (25,26), the acyl chain composition of CL within an organism or cell type displays a remarkable degree of homogeneity (27). This is achieved via acyl chain remodeling that is initiated by a lipase(s), generating monolyso-CL (MLCL, CL lacking one acyl chain), and completed by a transacylase or an acyltransferase that reacylates MLCL (28).…”

Membrane lipids and cell signaling

“…Asymmetry, for instance, is largely a product of enriched varieties of lipids within distinct membrane leaflets. In mammalian cells, the PM cytoplasmic leaflet usually contains more phosphatidylethanolamine (PE) and phosphatidylserine (PS) when compared with the outer leaflet rich in sphingolipids [4]. In addition, lipids can exhibit different overall geometric shapes based on inherent properties, such as head group size and the length and/or saturation of their acyl chain tails [5,6].…”