Extensive amino acid polymorphism at the pgm locus is consistent with adaptive protein evolution in Drosophila melanogaster.
PGM plays a central role in the glycolytic pathway at the branch point leading to glycogen metabolism and is highly polymorphic in allozyme studies of many species. We have characterized the nucleotide diversity across the Pgm gene in Drosophila melanogaster and D. simulans to investigate the role that protein polymorphism plays at this crucial metabolic branch point shared with several other enzymes. Although D. melanogaster and D. simulans share common allozyme mobility alleles, we find these allozymes are the result of many different amino acid changes at the nucleotide level. In addition, specific allozyme classes within species contain several amino acid changes, which may explain the absence of latitudinal clines for PGM allozyme alleles, the lack of association of PGM allozymes with the cosmopolitan In(3L)P inversion, and the failure to detect differences between PGM allozymes in functional studies. We find a significant excess of amino acid polymorphisms within D. melanogaster when compared to the complete absence of fixed replacements with D. simulans. There is also strong linkage disequilibrium across the 2354 bp of the Pgm locus, which may be explained by a specific amino acid haplotype that is high in frequency yet contains an excess of singleton polymorphisms. Like G6pd, Pgm shows strong evidence for a branch point enzyme that exhibits adaptive protein evolution.
Verrelli
B C
BC
Department of Ecology and Evolution, State University of New York, Stony Brook, New York 11794-5245, USA. verrelli@life.bio.sunysb.edu
Eanes
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WF
D000222:Adaptation, Physiological / Q000235:genetics*; D000483:Alleles; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D007446:Chromosome Inversion; D004330:Drosophila / Q000145:classification / Q000235:genetics; D004331:Drosophila melanogaster / Q000235:genetics* / Q000502:physiology; D019143:Evolution, Molecular; D015723:Gene Library; D006019:Glycolysis / Q000235:genetics; D006239:Haplotypes / Q000235:genetics; D019476:Insect Proteins / Q000235:genetics*; D007814:Larva; D015810:Linkage Disequilibrium; D008969:Molecular Sequence Data; D009656:North America; D010733:Phosphoglucomutase / Q000235:genetics*; D011110:Polymorphism, Genetic; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D015030:Zimbabwe
D019476:Insect Proteins; D010733:Phosphoglucomutase