From hopanoids to cholesterol : molecular clocks of pentameric ligand-gated ion channels

• Autores: Barrantes, Francisco José; Fantini, Jacques
• Año de publicación: 2016
• Idioma: español castellano
• Tipo de recurso: artículo
• Fuente: Progress in Lipid Research. 2016, 63
• Materia: COLESTEROL; CANALES IONICOS; HOPANOIDES; ESTEROIDES
• Institución: Pontificia Universidad Católica Argentina

Fil: Barrantes, Francisco José. Pontificia Universidad Católica Argentina. Facultad de Ciencias Médicas. Instituto de Investigaciones Biomédicas. Laboratorio de Neurobiología Molecular; Argentina
Fil: Barrantes, Francisco José. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
Fil: Fantini, Jacques. Aix-Marseille Université. Interactions Moléculaires et Systèmes Membranaires; Francia
Abstract: Pentameric ligand-gated ion channels (pLGICs) and their lipid microenvironments appear to have acquired mutually adaptive traits along evolution: 1) the three-ring architecture of their transmembrane (TM) region; 2) the ability of the outermost TM ring to convey lipid signals to the middle ring, which passes them on to the central pore ring, and 3) consensus motifs for sterol recognition in all pLGICs. Hopanoids are triterpenoid fossil lipids that constitute invaluable biomarkers for tracing evolution at the molecular scale. The cyanobacterium Gloeobacter violaceus is the oldest known living organism in which the X-ray structure of its pLGIC, GLIC, reveals the presence of the above attributes and, as discussed in this review, the ability to bind hopanoids. ELIC, the pLGIC from the bacillus Erwinia chrysanthemi is the only other known case to date. Both prokaryotes lack cholesterol but their pLGICs exhibit the same sterol motifs as mammalian pLGIC. This remarkable conservation suggests that the association of sterols and hopanoid surrogate molecules arose from the early need in prokaryotes to stabilize pLGIC TM regions by means of relatively rigid lipid molecules. The conservation of these phenotypic traits along such a long phylogenetic span leads us to suggest the possible co-evolution of these sterols with pLGICs.