Origins and evolution of the phospholipid biosynthetic pathways in the three domains of life. Implications for the membrane nature of the cenancestor
type: Dataset
description: The main bases of Biology suggest that all extant organisms share a last common ancestor, namely the cenancestor. As soon as the comparison of molecular characters of organisms representative of the whole diversity of life became possible, hot debates emerged about the environmental conditions in which the cenancestor lived, its closeness to the origins of life, its single or community nature and its relationships with the three domains of life (Archaea, Bacteria and Eucarya). However, available information about current organisms was for a long time inadequate to precisely describe the biology of this organism. For instance, the observation that the main archaeal membrane components, called phospholipids, are synthesized by different means than their bacterial/eukaryotic counterparts was proposed to reveal that modern phospholipid biosynthesis pathways emerged late in independent lineages and were, therefore, absent in the cenancestor. This hypothesis argued that the cenancestor had no lipid membranes, so it could not be a cellular organism although other indirect clues indicated the opposite. These contradictions raise the question of the presence in modern organisms of traces that the cenancestor had a phospholipid biosynthesis machinery.In this dissertation, I took advantage from the recent accumulation of genomic data to address this issue. Previous work had shown that the members of two universal protein superfamilies could be present in the cenancestor to carry out the non-specific synthesis of the glycerol phosphate enantiomers that are the backbones of modern phospholipids. Bacterial and eukaryotic phospholipids use fatty acids whereas archaeal phospholipids are made up of isoprenoids. Thus, I studied the evolution of the metabolic pathways that synthesize these molecules and build up the phospholipids from their components. My results show that the eukaryotic isoprenoid biosynthesis pathway and a hypothetical archaeal fatty acid biosynthesis pathway are li…
identifier: NNT: 2012PA112369
issued: 2026-05-11T06:10:40.990145
language: fr
modified: 2026-05-11T06:10:40.990150
contact point: Organization
  fn: CCSD
keyword: archaea
keyword: archees
keyword: bacteria
keyword: bacteries
keyword: biosynthesis-pathway
keyword: cenancestor
keyword: cenancetre
keyword: eucarya
keyword: eucaryotes
keyword: evolution
keyword: infoeu-reposemanticsdoctoralthesis
keyword: membrane
keyword: metabolism
keyword: metabolisme
keyword: phospholipid
keyword: phospholipides
keyword: sdvsalife-sciences-q-bioagricultural-sciences
keyword: theses
keyword: voie-de-biosynthese
landing page: https://theses.hal.science/tel-00819686

Origins and evolution of the phospholipid biosynthetic pathways in the three domains of life. Implications for the membrane nature of the cenancestor
type: Distribution
format: HTML
issued: 2026-05-11T06:10:41.031815
modified: 2026-05-11T06:10:40.966622
access URL: https://theses.hal.science/tel-00819686

test_moissonnage_selune
type: Agent