Differential enzyme targeting as an evolutionary adaptation to herbivory in carnivora

Not all members of the order Carnivora are carnivorous. Some are omnivorous, and a few, such as the giant panda, Ailuropoda melanoleuca, are almost exclusively herbivorous. Although a number of adaptations to increased plant-eating are recognized within Carnivora, few have been studied at the molecu...

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Bibliographic Details
Published in:Molecular biology and evolution 2004-04, Vol.21 (4), p.632-646
Main Authors: Birdsey, Graeme M, Lewin, Jackie, Cunningham, Andrew A, Bruford, Michael W, Danpure, Christopher J
Format: Article
Language:English
Subjects:
Adaptation, Biological - genetics
Amino Acid Sequence
Animals
Carnivora - classification
Carnivora - genetics
Carnivora - metabolism
Evolution, Molecular
Food Preferences
Green Fluorescent Proteins - analysis
Green Fluorescent Proteins - genetics
Microscopy, Immunoelectron
Mitochondria - ultrastructure
Molecular Sequence Data
Peroxisomes - ultrastructure
Phylogeny
Sequence Alignment
Transaminases - analysis
Transaminases - genetics
Transaminases - metabolism
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Summary:Not all members of the order Carnivora are carnivorous. Some are omnivorous, and a few, such as the giant panda, Ailuropoda melanoleuca, are almost exclusively herbivorous. Although a number of adaptations to increased plant-eating are recognized within Carnivora, few have been studied at the molecular level. One molecular adaptation to diet that is spread widely across Mammalia is the differential intracellular targeting of the intermediary metabolic enzyme alanine:glyoxylate aminotransferase (AGT), which tends to be mitochondrial in carnivores, peroxisomal in herbivores, and both mitochondrial and peroxisomal in omnivores. In the present study, we have analyzed the targeting of AGT in Carnivora in relation to species' natural diets. We show not only that there has been an adaptive shift in AGT targeting from the mitochondrion toward the peroxisome as diets have shifted from being mainly carnivorous to ones that are more omnivorous and herbivorous but also that in one lineage, namely that of the giant panda, there is evidence for positive selection pressure at the molecular level on the AGT mitochondrial targeting sequence to decrease its efficiency, thereby allowing more AGT to be targeted to the peroxisomes.
ISSN:0737-4038
DOI:10.1093/molbev/msh054