Epiplasts: Membrane Skeletons and Epiplastin Proteins in Euglenids, Glaucophytes, Cryptophytes, Ciliates, Dinoflagellates, and Apicomplexans.

摘要: ABSTRACT Animals and amoebae assemble actin/spectrin-based plasma membrane skeletons, forming what is often called the cell cortex, whereas euglenids alveolates (ciliates, dinoflagellates, apicomplexans) have been shown to a thin, viscoelastic, actin/spectrin-free skeleton, here epiplast. Epiplasts include class of proteins, epiplastins, with head/medial/tail domain organization, whose medial domains characterized in previous studies by their low-complexity amino acid composition. We identified two additional features domains: strong enrichment acid/base dyads predicted β-strand/random coil secondary structure. These served identify members unicellular eukaryotic radiations—the glaucophytes cryptophytes—as well as euglenids. analyzed composition structure 219 epiplastin sequences used quick-freeze deep-etch electron microscopy visualize epiplasts cryptophytes. define epiplastins proteins encoded organisms that epiplasts, but epiplastin-like unknown function, are also Insecta, Basidiomycetes, Caulobacter genomes. discuss diverse cellular traits supported propose evolutionary scenarios consonant distribution extant eukaryotes. IMPORTANCE Membrane skeletons associate inner surface provide support for fragile lipid bilayer an elastic framework itself. Several radiations, including animals, organize such using actin/spectrin four major radiations organisms, disease-causing parasites Plasmodium, known construct alternative essential skeleton (the epiplast) we term epiplastins. present images microscopy. analyze in-depth overview analysis posited roles organization parasite infection. An understanding epiplast assembly may suggest therapeutic approaches combat infectious agents Plasmodium engineering useful viscoelastic biofilms.