Document Detail


Aphid amino acid transporter regulates glutamine supply to intracellular bacterial symbionts.
MedLine Citation:
PMID:  24367072     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Endosymbiotic associations have played a major role in evolution. However, the molecular basis for the biochemical interdependence of these associations remains poorly understood. The aphid-Buchnera endosymbiosis provides a powerful system to elucidate how these symbioses are regulated. In aphids, the supply of essential amino acids depends on an ancient nutritional symbiotic association with the gamma-proteobacterium Buchnera aphidicola. Buchnera cells are densely packed in specialized aphid bacteriocyte cells. Here we confirm that five putative amino acid transporters are highly expressed and/or highly enriched in Acyrthosiphon pisum bacteriocyte tissues. When expressed in Xenopus laevis oocytes, two bacteriocyte amino acid transporters displayed significant levels of glutamine uptake, with transporter ACYPI001018, LOC100159667 (named here as Acyrthosiphon pisum glutamine transporter 1, ApGLNT1) functioning as the most active glutamine transporter. Transporter ApGLNT1 has narrow substrate selectivity, with high glutamine and low arginine transport capacity. Notably, ApGLNT1 has high binding affinity for arginine, and arginine acts as a competitive inhibitor for glutamine transport. Using immunocytochemistry, we show that ApGLNT1 is localized predominantly to the bacteriocyte plasma membrane, a location consistent with the transport of glutamine from A. pisum hemolymph to the bacteriocyte cytoplasm. On the basis of functional transport data and localization, we propose a substrate feedback inhibition model in which the accumulation of the essential amino acid arginine in A. pisum hemolymph reduces the transport of the precursor glutamine into bacteriocytes, thereby regulating amino acid biosynthesis in the bacteriocyte. Structural similarities in the arrangement of hosts and symbionts across endosymbiotic systems suggest that substrate feedback inhibition may be mechanistically important in other endosymbioses.
Authors:
Daniel R G Price; Honglin Feng; James D Baker; Selvan Bavan; Charles W Luetje; Alex C C Wilson
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2013-12-23
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  111     ISSN:  1091-6490     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  2014 Jan 
Date Detail:
Created Date:  2014-01-08     Completed Date:  2014-03-12     Revised Date:  2014-07-10    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  320-5     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Transport Systems / metabolism*
Animals
Aphids / metabolism*
Biological Transport
Buchnera / metabolism*
Cell Membrane / metabolism
Cloning, Molecular
Cytoplasm / metabolism
Gene Expression Profiling
Gene Expression Regulation
Glutamine / metabolism*
Hemolymph / metabolism
Host-Parasite Interactions
Insect Proteins / metabolism*
Oocytes / metabolism
Symbiosis / genetics*,  physiology
Xenopus laevis
Grant Support
ID/Acronym/Agency:
DC011091/DC/NIDCD NIH HHS; R01 DC011091/DC/NIDCD NIH HHS
Chemical
Reg. No./Substance:
0/Amino Acid Transport Systems; 0/Insect Proteins; 0RH81L854J/Glutamine
Comments/Corrections

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