title: Biotic Host-Pathogen Interactions As Major Drivers of Plastid Endosymbiosis.
abstract: The plastid originated 1.5 billion years ago through a primary endosymbiosis involving a heterotrophic eukaryote and an ancient cyanobacterium. Phylogenetic and biochemical evidence suggests that the incipient endosymbiont interacted with an obligate intracellular chlamydial pathogen that housed it in an inclusion. This aspect of the ménage-à-trois hypothesis (MATH) posits that Chlamydiales provided critical novel transporters and enzymes secreted by the pathogens in the host cytosol. This initiated the efflux of photosynthate to both the inclusion lumen and host cytosol. Here we review the experimental evidence supporting the MATH and focus on chlamydial genes that replaced existing cyanobacterial functions. The picture emerging from these studies underlines the importance of chlamydial host-pathogen interactions in the metabolic integration of the primary plastid.
authors.affiliation: Université des Sciences et Technologies de Lille, Unité de Glycobiologie Structurale et Fonctionnelle, UMR8576 CNRS-USTL, Cité Scientifique, 59655 Villeneuve d'Ascq Cedex, France.
authors.forename: Ugo
authors.initials: U
authors.lastname: Cenci
authors.affiliation: Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, NJ 08540, USA.
authors.forename: Debashish
authors.initials: D
authors.lastname: Bhattacharya
authors.affiliation: Institute for Plant Biochemistry, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-University, D-40225 Düsseldorf, Germany.
authors.forename: Andreas P M
authors.initials: APM
authors.lastname: Weber
authors.affiliation: Université des Sciences et Technologies de Lille, Unité de Glycobiologie Structurale et Fonctionnelle, UMR8576 CNRS-USTL, Cité Scientifique, 59655 Villeneuve d'Ascq Cedex, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Colleoni
authors.affiliation: Institut Pasteur, Unité de Biologie Cellulaire de l'Infection Microbienne, 25 Rue du Dr Roux, 75015 Paris, France.
authors.forename: Agathe
authors.initials: A
authors.lastname: Subtil
authors.affiliation: Université des Sciences et Technologies de Lille, Unité de Glycobiologie Structurale et Fonctionnelle, UMR8576 CNRS-USTL, Cité Scientifique, 59655 Villeneuve d'Ascq Cedex, France. Electronic address: steven.ball@univ-lille1.fr.
authors.forename: Steven G
authors.initials: SG
authors.lastname: Ball
mesh_terms: D005075:Biological Evolution; D002689:Chlamydia / Q000378:metabolism / Q000502:physiology; D006003:Glycogen / Q000378:metabolism; D054884:Host-Pathogen Interactions; D018087:Plastids / Q000378:metabolism*; D013559:Symbiosis / Q000235:genetics / Q000502:physiology*
chemical_list: D006003:Glycogen
keywords: T3SS; bacterial conjugation; chlamydia; evolution of plastids; glycogen metabolism; tryptophan synthesis