A metabolic study of Buchnera, the intracellular bacterial symbionts of the pea aphid Acyrthosiphon pisum

Whitehead, Lynne; Douglas, Angela E.

doi:10.1099/00221287-139-4-821

Cited by 37 publications

(22 citation statements)

References 22 publications

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“…Previously, the only preparations available have been fractionated aphid homogenates with low yields often contaminated by other aphid-associated bacteria. Cell lines bearing secondary symbionts not only provide a new platform for the development of novel approaches and technologies to control insect pests but also have potential as a source of material for genomic analyses and short-term physiological studies of the bacteria in defined media (40). They make possible fundamental studies of the interactions between insect symbionts and animal cells, including the extent to which the establishment and persistence of intracellular symbiosis is dependent on traits also displayed by overt pathogens (37).…”

Section: Discussionmentioning

confidence: 99%

Aphid-Symbiotic Bacteria Cultured in Insect Cell Lines

Darby

Chandler

Welburn

et al. 2005

Appl Environ Microbiol

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The cells and tissues of many aphids contain bacteria known as "secondary symbionts," which under specific environmental circumstances may be beneficial to the host insect. Such symbiotic bacteria are traditionally described as intractable to cultivation in vitro. Here we show that two types of aphid secondary symbionts, known informally as T type and U type, can be cultured and maintained in three insect cell lines. The identities of the cultured bacteria were confirmed by PCR with sequencing of 16S rRNA gene fragments and fluorescence in situ hybridization. In cell lines infected with bacteria derived from aphids harboring both T type and U type, the U type persisted, while the T type was lost. We suggest that the two bacteria persist in aphids because competition between them is limited by differences in tropism for insect tissues or cell types. The culture of these bacteria in insect cell lines provides a new and unique research opportunity, offering a source of unibacterial material for genomic studies and a model system to investigate the interactions between animal cells and bacteria. We propose the provisional taxon names "Candidatus Consessoris aphidicola" for T type and "Candidatus Adiaceo aphidicola" for U type.

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Section: Discussionmentioning

confidence: 99%

Aphid-Symbiotic Bacteria Cultured in Insect Cell Lines

Darby

Chandler

Welburn

et al. 2005

Appl Environ Microbiol

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“…Buchnera growth is inferred to require 33 host-derived metabolites (11,16), and there is no reasonable prospect of culturing this bacterium. Despite this, viable and metabolically active Buchnera cells persist in defined medium for some hours (17)(18)(19), facilitating direct investigation of their metabolic capabilities. In this study, we probed the metabolic functions of isolated Buchnera preparations and obtained direct evidence that metabolic pathways are shared between host and symbiont.…”

Section: Discussionmentioning

confidence: 99%

Shared Metabolic Pathways in a Coevolved Insect-Bacterial Symbiosis

Russell

Bouvaine

Newell

et al. 2013

Appl Environ Microbiol

104

112

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The symbiotic bacterium Buchnera aphidicola lacks key genes in the biosynthesis of five essential amino acids (EAAs), and yet its animal hosts (aphids) depend on the symbiosis for the synthesis of these EAAs (isoleucine, leucine, methionine, phenylalanine, and valine). We tested the hypothesis, derived from genome annotation, that the missing Buchnera reactions are mediated by host enzymes, with the exchange of metabolic intermediates between the partners. The specialized host cells bearing Buchnera were separated into a Buchnera fraction and a Buchnera-free host cell fraction (HF). Addition of HF to isolated Buchnera preparations significantly increased the production of leucine and phenylalanine, and recombinant enzymes mediating the final reactions in branched-chain amino acid and phenylalanine synthesis rescued the production of these EAAs by Buchnera preparations without HF. The likely precursors for the missing proximal reactions in isoleucine and methionine synthesis were identified, and they differed from predictions based on genome annotations: synthesis of 2-oxobutanoate, the aphid-derived precursor of isoleucine synthesis, was stimulated by homoserine and not threonine via threonine dehydratase, and production of the homocysteine precursor of methionine was driven by cystathionine, not cysteine, via reversal of the transsulfuration pathway. The evolution of shared metabolic pathways in this symbiosis can be attributed to host compensation for genomic deterioration in the symbiont, involving changes in host gene expression networks to recruit specific enzymes to the host cell.

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“…Given that the proteome analysis was conducted on precisely-aged larval aphids in which Buchnera degradation is minimal (51,63,78), this result suggests that lysozyme is not important in regulation of the functional symbiosis. As reported previously (78), lysozyme may contribute to the orchestrated symbiosis breakdown in older insects.…”

Section: Absence Of Selective Protein Transfer Between Aphid Andmentioning

confidence: 99%