Postsymbiotic plasmid acquisition and evolution of the repA1-replicon in Buchnera aphidicola
AUTOR(ES)
Van Ham, Roeland C. H. J.
FONTE
The National Academy of Sciences
RESUMO
Buchnera aphidicola is an obligate, strictly vertically transmitted, bacterial symbiont of aphids. It supplies its host with essential amino acids, nutrients required by aphids but deficient in their diet of plant phloem sap. Several lineages of Buchnera show adaptation to their nutritional role in the form of plasmid-mediated amplification of key-genes involved in the biosynthesis of tryptophan (trpEG) and leucine (leuABCD). Phylogenetic analyses of these plasmid-encoded functions have thus far suggested the absence of horizontal plasmid exchange among lineages of Buchnera. Here, we describe three new Buchnera plasmids, obtained from species of the aphid host families Lachnidae and Pemphigidae. All three plasmids belong to the repA1 family of Buchnera plasmids, which is characterized by the presence of a repA1-replicon responsible for replication initiation. A comprehensive analysis of this family of plasmids unexpectedly revealed significantly incongruent phylogenies for different plasmid and chromosomally encoded loci. We infer from these incongruencies a case of horizontal plasmid transfer in Buchnera. This process may have been mediated by secondary endosymbionts, which occasionally undergo horizontal transmission in aphids.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=27113Documentos Relacionados
- Expression and regulation of the RepA protein of the RepFIB replicon from plasmid P307.
- Monomers and dimers of the RepA protein in plasmid pSC101 replication: domains in RepA.
- Reductive genome evolution in Buchnera aphidicola
- Role of the RepA1 protein in RepFIC plasmid replication.
- Interactions of the RepA1 protein with its replicon targets: two opposing roles in control of plasmid replication.