title: Multimodal dynamic response of the Buchnera aphidicola pLeu plasmid to variations in leucine demand of its host, the pea aphid Acyrthosiphon pisum.
abstract: Aphids, important agricultural pests, can grow and reproduce thanks to their intimate symbiosis with the γ-proteobacterium Buchnera aphidicola that furnishes them with essential amino acids lacking in their phloem sap diet. To study how B. aphidicola, with its reduced genome containing very few transcriptional regulators, responds to variations in the metabolic requirements of its host, we concentrated on the leucine metabolic pathway. We show that leucine is a limiting factor for aphid growth and it displays a stimulatory feeding effect. Our metabolic analyses demonstrate that symbiotic aphids are able to respond to leucine starvation or excess by modulating the neosynthesis of this amino acid. At a molecular level, this response involves an early important transcriptional regulation (after 12 h of treatment) followed by a moderate change in the pLeu plasmid copy number. Both responses are no longer apparent after 7 days of treatment. These experimental data are discussed in the light of a re-annotation of the pLeu plasmid regulatory elements. Taken together, our data show that the response of B. aphidicola to the leucine demand of its host is multimodal and dynamically regulated, providing new insights concerning the genetic regulation capabilities of this bacterium in relation to its symbiotic functions.
authors.affiliation: UMR203 BF2I, Biologie Fonctionnelle Insectes et Interactions, INSA-Lyon, INRA, Université de Lyon, Bât. Louis Pasteur, 20 av. Albert Einstein, F-69621 Villeurbanne, France.
authors.forename: José
authors.initials: J
authors.lastname: Viñuelas
authors.forename: Gérard
authors.initials: G
authors.lastname: Febvay
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Duport
authors.forename: Stefano
authors.initials: S
authors.lastname: Colella
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Fayard
authors.forename: Hubert
authors.initials: H
authors.lastname: Charles
authors.forename: Yvan
authors.initials: Y
authors.lastname: Rahbé
authors.forename: Federica
authors.initials: F
authors.lastname: Calevro
mesh_terms: D000601:Amino Acids, Essential / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001042:Aphids / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology; D020635:Buchnera / Q000235:genetics / Q000378:metabolism*; D018556:Crops, Agricultural; D056915:DNA Copy Number Variations; D016680:Genome, Bacterial; D007930:Leucine / Q000096:biosynthesis; D053858:Metabolic Networks and Pathways / Q000235:genetics; D010957:Plasmids; D013559:Symbiosis / Q000235:genetics / Q000502:physiology
chemical_list: D000601:Amino Acids, Essential; D007930:Leucine