Bacterial Genes in the Aphid Genome: Absence of Functional Gene Transfer from Buchnera to Its Host

• DOI: 10.1371/journal.pgen.1000827
• Publication Date: 2010-03-02T19:11:01Z
• Authors: Naruo Nikoh; John P. McCutcheon; Toshiaki Kudo; Shin-ya Miyagishima; Nancy A. Moran; Atsushi Nakabachi
• Keywords: Buchnera; Horizontal Gene Transfer; Acyrthosiphon pisum; Obligate

Genome reduction is typical of obligate symbionts. In cellular organelles, this partly reflects transfer ancestral bacterial genes to the host genome, but little known about gene in other symbioses. Aphids harbor anciently acquired mutualists, Buchnera aphidicola (Gammaproteobacteria), which have highly reduced genomes (420–650 kb), raising possibility from aphid genome. addition, aphids often bacteria that also are potential sources transferred genes. Previous limited sampling expressed bacteriocytes, specialized cells Buchnera, revealed at least two bacteria. The newly sequenced genome pea aphid, Acyrthosiphon pisum, presents first opportunity for a complete inventory context an ancient symbiosis. Computational screening entire A. pisum followed by phylogenetic and experimental analyses, provided strong support 12 or fragments genome: three LD–carboxypeptidases (LdcA1, LdcA2,ψLdcA), five rare lipoprotein As (RlpA1-5), N-acetylmuramoyl-L-alanine amidase (AmiD), 1,4-beta-N-acetylmuramidase (bLys), DNA polymerase III alpha chain (ψDnaE), ATP synthase delta (ψAtpH). was apparent source truncated pseudogenes (ψDnaE ψAtpH). Most were closely related relatives Wolbachia (Alphaproteobacteria). At eight AmiD, RlpA1-5, bLys) appear be functional, expression seven RlpA1-5) upregulated bacteriocytes. LdcAs RlpAs been duplicated after transfer. Our results excluded hypothesis has accompanied nuclear suggest utilize set Buchnera–aphid mutualism.