The mitochondrial aspartate/glutamate carrier (AGC or Aralar1) isoforms in D. melanogaster: biochemical characterization, gene structure, and evolutionary analysis

Biochim Biophys Acta Gen Subj. 2021 May;1865(5):129854. doi: 10.1016/j.bbagen.2021.129854. Epub 2021 Jan 23.

Abstract

Background: In man two mitochondrial aspartate/glutamate carrier (AGC) isoforms, known as aralar and citrin, are required to accomplish several metabolic pathways. In order to fill the existing gap of knowledge in Drosophila melanogaster, we have studied aralar1 gene, orthologue of human AGC-encoding genes in this organism.

Methods: The blastp algorithm and the "reciprocal best hit" approach have been used to identify the human orthologue of AGCs in Drosophilidae and non-Drosophilidae. Aralar1 proteins have been overexpressed in Escherichia coli and functionally reconstituted into liposomes for transport assays.

Results: The transcriptional organization of aralar1 comprises six isoforms, three constitutively expressed (aralar1-RA, RD and RF), and the remaining three distributed during the development or in different tissues (aralar1-RB, RC and RE). Aralar1-PA and Aralar1-PE, representative of all isoforms, have been biochemically characterized. Recombinant Aralar1-PA and Aralar1-PE proteins share similar efficiency to exchange glutamate against aspartate, and same substrate affinities than the human isoforms. Interestingly, although Aralar1-PA and Aralar1-PE diverge only in their EF-hand 8, they greatly differ in their specific activities and substrate specificity.

Conclusions: The tight regulation of aralar1 transcripts expression and the high request of aspartate and glutamate during early embryogenesis suggest a crucial role of Aralar1 in this Drosophila developmental stage. Furthermore, biochemical characterization and calcium sensitivity have identified Aralar1-PA and Aralar1-PE as the human aralar and citrin counterparts, respectively.

General significance: The functional characterization of the fruit fly mitochondrial AGC transporter represents a crucial step toward a complete understanding of the metabolic events acting during early embryogenesis.

Keywords: Aralar; Aspartate/glutamate carrier (AGC); CG2139; Citrin; Drosophila melanogaster; Phylogenetic footprint.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Transport Systems, Acidic / chemistry
  • Amino Acid Transport Systems, Acidic / genetics*
  • Amino Acid Transport Systems, Acidic / metabolism
  • Animals
  • Antiporters / chemistry
  • Antiporters / genetics*
  • Antiporters / metabolism
  • Calcium-Binding Proteins / chemistry
  • Calcium-Binding Proteins / genetics*
  • Calcium-Binding Proteins / metabolism
  • Drosophila Proteins / chemistry
  • Drosophila Proteins / genetics*
  • Drosophila Proteins / metabolism
  • Drosophila melanogaster / chemistry
  • Drosophila melanogaster / genetics*
  • Drosophila melanogaster / metabolism
  • Evolution, Molecular
  • Humans
  • Mitochondrial Membrane Transport Proteins / chemistry
  • Mitochondrial Membrane Transport Proteins / genetics*
  • Mitochondrial Membrane Transport Proteins / metabolism
  • Phylogeny
  • Protein Isoforms / chemistry
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism

Substances

  • Amino Acid Transport Systems, Acidic
  • Antiporters
  • Aralar protein, Drosophila
  • Calcium-Binding Proteins
  • Drosophila Proteins
  • Mitochondrial Membrane Transport Proteins
  • Protein Isoforms
  • aspartate-glutamate carrier