title: Structure and evolution of the leucine plasmids carried by the endosymbiont (Buchnera aphidicola) from aphids of the family Aphididae.
abstract: In all examined species of the family Aphididae, the bacterial endosymbiont Buchnera aphidicola carries a plasmid encoding the genes leuABCD (involved in leucine biosynthesis) along with repA1, repA2 and ORF1. The gene organisation of the leucine plasmids was conserved, except in Buchnera isolated from Pterocomma populeum, where ORF1 was located in a different position. An inverted repeat (LIR1) located between repA2 and leuA is found in all of the Buchnera leucine plasmids examined. The predicted secondary structure of the LIR1 transcript conforms to a long hairpin loop, suggesting an involvement in transcription termination or messenger stability. Phylogenetic reconstruction based on repA2 sequences suggests that horizontal transfer of Buchnera leucine plasmids has not occurred.
authors.affiliation: Institut Universitari Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València, Spain. Francisco.Silva@uv.es
authors.forename: F J
authors.initials: FJ
authors.lastname: Silva
authors.forename: R C
authors.initials: RC
authors.lastname: van Ham
authors.forename: B
authors.initials: B
authors.lastname: Sabater
authors.forename: A
authors.initials: A
authors.lastname: Latorre
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001042:Aphids / Q000145:classification / Q000382:microbiology*; D001483:Base Sequence; D002874:Chromosome Mapping; D004755:Enterobacteriaceae / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D007930:Leucine / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D016366:Open Reading Frames; D010802:Phylogeny; D010957:Plasmids / Q000235:genetics*; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid; D016415:Sequence Alignment; D013559:Symbiosis
chemical_list: D012329:RNA, Bacterial; D012333:RNA, Messenger; D007930:Leucine