Genetics, physiology, and evolutionary relationships of the genus Buchnera: Intracellular symbionts of aphids

Paul Baumann, Linda Baumann, Chi Yung Lai, Dadbeh Rouhbakhsh, Nancy A. Moran, Marta A. Clark

Research output: Contribution to journalReview article

386 Citations (Scopus)

Abstract

Evolutionary studies suggest that 200-250 million years ago an aphid ancestor was infected with a free-living eubacterium. The latter became established within aphid cells. Host and endosymbiont (genus Buchnera) became interdependent and unable to survive without each other. The growth of Buchnera became integrated with that of the aphids, which acquired the endosymbionts from their mothers before birth. Speciation of host lineages was paralleled by divergence of associated endosymbiont lineages, resulting in parallel evolution of Buchnera and aphids. Present day Buchnera retains many of the properties of its free-living ancestor, containing genes for proteins involved in DNA replication, transcription, and translation, as well as chaperonins and proteins involved in secretion, energy-yielding metabolism, and amino acid biosynthesis. Some of these processes are also observed in isolated endosymbiont cells. Genetic and physiological studies indicate that Buchnera can synthesize methionine, cysteine, and tryptophan and supply these amino acids to the aphid host. In the case of some fast- growing species of aphids, the overproduction of tryptophan by Buchnera involves plasmid-amplification of the gene coding for anthranilate synthase, the first enzyme of the tryptophan biosynthetic pathway. These recent studies provide a beginning in our understanding of Buchnera and its role in the endosymbiosis with aphids.

Original languageEnglish
Pages (from-to)55-94
Number of pages40
JournalAnnual Review of Microbiology
Volume49
DOIs
Publication statusPublished - 1995 Jan 1

All Science Journal Classification (ASJC) codes

  • Microbiology

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