The proteome of the pea aphid bacteriocyte and the symbiotic bacterium Buchnera aphidicola

The recent release of the pea aphid genome has created many new opportunities for exploring the symbiosis between the pea aphid, Acyrthosiphon pisum and its intracellular symbiotic bacterium, Buchnera aphidicola. In particular, proteomic approaches coupled with fractionation techniques have allowed us to quantify the protein composition of the aphid and bacterial fraction of the specialized aphid cells, bacteriocytes, which house the symbiotic bacteria. A total of 1274 aphid proteins and 404 Buchnera proteins (including proteins coded on the plasmids) were found to be associated within the bacteriocyte. When compared to proteomic data obtained from whole aphids, we are able to determine enrichment of individual proteins and of enzymes mediating metabolic pathways within the bacteriocytes. These data provide the basis to predict the metabolic and nutritional interactions between the partners and to develop a greater understanding of the mechanisms by which the bacterial populations are regulated.