Contrasting Molecular Population Genetics of Four Hexokinases in Drosophila melanogaster, D. simulans and D. yakuba


As part of a larger study contrasting patterns of variation in regulatory and nonregulatory enzymes of the central metabolic pathways we have examined the molecular variation in four uncharacterized hexokinase genes unique to muscle, fat body, and testis in Drosophila melanogaster, D. simulans, and D. yakuba. Earlier isoenzyme studies had designated these genes as Hex-A, Hex-C, and Hex-t. There are two tightly linked testes-specific genes designated here as Hex-t1 and Hex-t2. Substantial and concordant differences across species are seen in levels of both amino acid and silent polymorphism. The flight muscle form Hex-A is the most conserved followed by the fat body hexokinase Hex-C and testis-specific hexokinases Hex-t1 and Hex-t2. While constraints acting at the amino acid level are expected, the silent polymorphisms follow this pattern as well. All genes are in regions of normal recombination, therefore hitchhiking and background selection are not likely causes of interlocus differences. In D. melanogaster latitudinal clines are seen for amino acid polymorphisms at the Hex-C and Hex-t2 loci. There is evidence for accelerated amino acid substitution in Hex-t1 that has lost residues known to be associated with glucose and glucose-6-phosphate binding. D. simulans shows substantial linkage phase structuring that suggests historical population subdivision.


Biological Sciences

Keywords and Phrases

amino acid; glucose; glucose 6 phosphate; hexokinase; amino acid substitution; Drosophila; Drosophila melanogaster; Drosophila simulans; enzyme regulation; gene locus; genetic linkage; genetic polymorphism; genetic recombination; nonhuman; population genetics; priority journal; species difference; Adipose Tissue; Amino Acid Sequence; Animals; Base Sequence; Chromosome Mapping; Drosophila; Drosophila melanogaster; Female; Genetics; Population; Hexokinase; Isoenzymes; Molecular Sequence Data; Organ Specificity; Sequence Alignment; Sequence Homology; Amino Acid; Variation (Genetics); Arachnida; Drosophila melanogaster; Drosophila simulans; Drosophila yakuba; Hexapoda; Melanogaster

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Article - Journal

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© 2000 Genetics Society of America, All rights reserved.

Publication Date

01 Nov 2000