Proton-dependent glutamine uptake by aphid bacteriocyte amino acid transporter ApGLNT1

Daniel R G Price, Alexandra Wilson, Charles W Luetje

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Aphids house large populations of the gammaproteobacterial symbiont Buchnera aphidicola in specialized bacteriocyte cells. The combined biosynthetic capability of the holobiont (Acyrthosiphon pisum and Buchnera) is sufficient for biosynthesis of all twenty protein coding amino acids, including amino acids that animals alone cannot synthesize; and that are present at low concentrations in A. pisum's plant phloem sap diet. Collaborative holobiont amino acid biosynthesis depends on glutamine import into bacteriocytes, which serves as a nitrogen-rich amino donor for biosynthesis of other amino acids. Recently, we characterized A. pisum glutamine transporter 1 (ApGLNT1), a member of the amino acid/auxin permease family, as the dominant bacteriocyte plasma membrane glutamine transporter. Here we show ApGLNT1 to be structurally and functionally related to mammalian proton-dependent amino acid transporters (PATs 1-4). Using functional expression in Xenopus laevis oocytes, combined with two-electrode voltage clamp electrophysiology we demonstrate that ApGLNT1 is electrogenic and that glutamine induces large inward currents. ApGLNT1 glutamine induced currents are dependent on external glutamine concentration, proton (H<sup>+</sup>) gradient across the membrane, and membrane potential. Based on these transport properties, ApGLNT1-mediated glutamine uptake into A. pisum bacteriocytes can be regulated by changes in either proton gradients across the plasma membrane or membrane potential.

Original languageEnglish (US)
Pages (from-to)2085-2091
Number of pages7
JournalBiochimica et Biophysica Acta - Biomembranes
Volume1848
Issue number10
DOIs
StatePublished - Jul 11 2015

Keywords

  • Amino acid/auxin permease
  • Electrogenic transport
  • Holobiont
  • Symbiosis

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Biophysics

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