Characterization of Gfat1 (zeppelin) and Gfat2, Essential Paralogous Genes Which Encode the Enzymes That Catalyze the Rate-Limiting Step in the Hexosamine Biosynthetic Pathway in Drosophila melanogaster.

Shawn Cotsworth,Arthur J Hilliker,Kathleen A Fitzpatrick,Esther M Verheyen,Catherine J Jackson,Donald A Sinclair,Graham Hallson,Simon J H Wang,Alistair B Coulthard,Amy Bejsovec,Sergio Pimpinelli,Monika Syrzycka,Robert G Camfield,Marcella Marchetti,Barry M Honda

doi:10.3390/cells11030448

Abstract

The zeppelin (zep) locus is known for its essential role in the development of the embryonic cuticle of Drosophila melanogaster. We show here that zep encodes Gfat1 (Glutamine: Fructose-6-Phosphate Aminotransferase 1; CG12449), the enzyme that catalyzes the rate-limiting step in the hexosamine biosynthesis pathway (HBP). This conserved pathway diverts 2%–5% of cellular glucose from glycolysis and is a nexus of sugar (fructose-6-phosphate), amino acid (glutamine), fatty acid [acetyl-coenzymeA (CoA)], and nucleotide/energy (UDP) metabolism. We also describe the isolation and characterization of lethal mutants in the euchromatic paralog, Gfat2 (CG1345), and demonstrate that ubiquitous expression of Gfat1+ or Gfat2+ transgenes can rescue lethal mutations in either gene. Gfat1 and Gfat2 show differences in mRNA and protein expression during embryogenesis and in essential tissue-specific requirements for Gfat1 and Gfat2, suggesting a degree of functional evolutionary divergence. An evolutionary, cytogenetic analysis of the two genes in six Drosophila species revealed Gfat2 to be located within euchromatin in all six species. Gfat1 localizes to heterochromatin in three melanogaster-group species, and to euchromatin in the more distantly related species. We have also found that the pattern of flanking-gene microsynteny is highly conserved for Gfat1 and somewhat less conserved for Gfat2.

Highlights

The hexosamine biosynthesis pathway (HBP) diverts fructose-6-phosphate from glycolysis to generate UDP-Nacetylglucosamine, an important precursor used in the formation of glycoproteins (e.g., GlcNAcylation by OGT, O-GlcNAc transferase), proteoglycans, and other important biomolecules 4.0/).GlcNAcylation by OGT, O-GlcNAc transferase), proteoglycans, and other im molecules (Figure 1) [1,2,3,4]
LP13 is further evidence that the zep locu failed to complement zepencodes phenotypes and because mmy an HBP enzyme, a reasonable hypothesis is that the sponds toGfat1 the Gfat1 gene. to the zep locus
The fact that on the failure to complement zep from a large collection of EMS-induced rece the Gfat1 insertion allele, y w* ; Mi{MIC}Gfat1MI11277 /TM3, Sb Ser (BDSC 56582), failed to thal mutations provided by the isZuker

Summary

Introduction

The HBP diverts fructose-6-phosphate from glycolysis to generate UDP-Nacetylglucosamine, an important precursor used in the formation of glycoproteins (e.g., GlcNAcylation by OGT, O-GlcNAc transferase), proteoglycans, and other important biomolecules 4.0/).GlcNAcylation by OGT, O-GlcNAc transferase), proteoglycans, and other im molecules (Figure 1) [1,2,3,4]. The rate-limiting step in the pathway is catalyze mine-fructose-6-phosphate transaminase 1 or GFPT1 in humans (hereafter ca and Gfat in Drosophila, and Glutamine-fructose-6-phosphate transaminase in humans (hereafter calledstep hGfat). The rate-limiting in the pathway is catalyzed by Glutamine-fructose6-phosphate transaminase. Gfat are encoded two separate genes, Drosophila, and Glutamine-fructose-6-phosphate transaminase or GFPT2 in humans be the case for Aedes aegypti [5,6,7,8]. It appears that there is only a (hereafter called hGfat2) and Gfat in Drosophila. In Drosophila, C. elegans, mice, and gene/enzyme inGfat fungi distinction between hGfat and is t humans, Gfat and are[9,10,11]

Methods

Results

Conclusion