The eisosome core is composed of BAR domain proteins

Abstract

The core components of eisosomes, Pil1 and Lsp1, are membrane-sculpting BAR proteins. In addition, TORC2 substrates Slm1 and Slm2 have F-BAR domains that are needed for targeting into eisosomes. Results support a model in which BAR domain protein-mediated membrane bending leads to domain formation within the plasma membrane.

Eisosomes Regulate Phosphatidylinositol 4,5-Bisphosphate (PI(4,5)P2) Cortical Clusters and Mitogen-activated Protein (MAP) Kinase Signaling upon Osmotic Stress

“…Beyond positioning, we speculate that eisosomes may play a role in cluster assembly and/or turnover. The lipids encased within a cellular eisosome are unknown, but the core eisosome protein Pil1 binds preferentially to negatively charged lipids including PI 4-phosphate and PI(4,5)P 2 in vitro (4,(7)(8)(9). Thus, eisosomes may inhibit PI(4,5)P 2 cluster formation by sequestering this phospholipid or its precursor PI 4-phosphate.…”

“…Recent studies have also uncovered eisosome structures at the plasma membrane of microalgae and lichens (6). The core component of yeast eisosomes is a BAR domain protein called Pil1, which directly binds to lipids and provides structural curvature to these plasma membrane invaginations (7)(8)(9).…”

Eisosomes provide membrane reservoirs for rapid expansion of the yeast plasma membrane

“…Eisosome-like invaginations are found in a wide range of fungal and algal cells despite divergent molecular components (Lee et al, 2015), suggesting that eisosome function might be intricately linked to this topology. The primary component of yeast eisosomes is the BAR domain protein Pil1, which directly binds lipids at the membrane to generate invaginations (Kabeche et al, 2011(Kabeche et al, , 2014Karotki et al, 2011;Moreira et al, 2009;Olivera-Couto et al, 2011;Stradalova et al, 2009;Ziółkowska et al, 2011). Recent studies have linked eisosome function with the control of signaling pathways (Berchtold et al, 2012;Frohlich et al, 2014;Kabeche et al, 2014), but we noted that their architecture possesses the capacity to act as a membrane reservoir.…”

Eisosome Ultrastructure and Evolution in Fungi, Microalgae, and Lichens

“…Homologues of genes encoding Pil1p and Lsp1p, the cytoplasmic proteins that dominate S. cerevisiae eisosomes (16), are restricted to the ascomycetes and basidiomycetes (28, 33; our BLAST results), a result that has generated the speculation that eisosomes are confined to the fungal kingdom (27).…”

“…Additional proteins also associate with these punctate domains, in some cases in a transient fashion (17), and the MCC component is reportedly enriched in ergosterol (18) and influenced by phosphoinositide (6,19,20) and sphingolipid (14,17,(21)(22)(23)(24) levels. Hence, the current yeast model (25,26) proposes that Pil1p and Lsp1p, which contain membrane curvatureinducing BAR domains (6,27,28), together with Seg1p (29,30), form a submembrane complex (6) reportedly influenced by Pil1p phosphorylation (25); this complex then either creates or associates with the MCC domains, presumably inducing an inward curvature. The MCC protein Nce102p has also been implicated in generating curvature (5,31).…”