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Research article2003Peer reviewedOpen access

A genomic perspective on nutrient provisioning by bacterial symbionts of insects

Moran NA, Plague GR, Sandstrom JP, Wilcox JL

Abstract

Many animals show intimate interactions with bacterial symbionts that provision hosts with limiting nutrients. The best studied such association is that between aphids and Buchnera aphidicola, which produces essential amino acids that are rare in the phloem sap diet. Genomic studies of Buchnera have provided a new means for inferring metabolic capabilities of the symbionts and their likely contributions to hosts. Despite evolutionary reduction of genome size, involving loss of most ancestral genes, Buchnera retains capabilities for biosynthesis of all essential amino acids. In contrast, most genes duplicating amino acid biosynthetic capabilities of hosts have been eliminated. In Buchnera of many aphids, genes for biosynthesis of leucine and tryptophan have been transferred from the chromosome to distinctive plasmids, a feature interpreted as a mechanism for overproducing these amino acids through gene amplification. However, the extent of plasmid-associated amplification varies between and within species, and plasmid-borne genes are sometimes fewer in number than single copy genes on the (polyploid) main chromosome. This supports the broader interpretation of the plasmid location as a means of achieving regulatory control of gene copy number and/or transcription. Buchnera genomes have eliminated most regulatory sequences, raising the question of the extent to which gene expression is moderated in response to changing demands imposed by host nutrition or other factors. Microarray analyses of the Buchnera transcriptome reveal only slight changes in expression of nutrition-related genes in response to shifts in host diet, with responses less dramatic than those observed for the related nonsymbiotic species, Escherichia coli

Published in

Proceedings of the National Academy of Sciences
2003, Volume: 100, pages: 14543-14548
Publisher: NATL ACAD SCIENCES

      SLU Authors

    • Sandström, Jonas

      • Department of Entomology, Swedish University of Agricultural Sciences

    UKÄ Subject classification

    Environmental Sciences related to Agriculture and Land-use

    Publication identifier

    DOI: https://doi.org/10.1073/pnas.2135345100

    Permanent link to this page (URI)

    https://res.slu.se/id/publ/1174