title: Increased phosphate transport of Arabidopsis thaliana Pht1;1 by site-directed mutagenesis of tyrosine 312 may be attributed to the disruption of homomeric interactions.
abstract: Members of the Pht1 family of plant phosphate (Pi) transporters play vital roles in Pi acquisition from soil and in planta Pi translocation to maintain optimal growth and development. The study of the specificities and biochemical properties of Pht1 transporters will contribute to improving the current understanding of plant phosphorus homeostasis and use-efficiency. In this study, we show through split in vivo interaction methods and in vitro analysis of microsomal root tissues that Arabidopsis thaliana Pht1;1 and Pht1;4 form homomeric and heteromeric complexes. Transient and heterologous expression of the Pht1;1 variants, Pht1;1(Y312D), Pht1;1(Y312A) and Pht1;1(Y312F), was used to analyse the role of a putative Pi binding residue (Tyr 312) in Pht1;1 transporter oligomerization and function. The homomeric interaction among Pht1;1 proteins was disrupted by mutation of Tyr 312 to Asp, but not to Ala or Phe. In addition, the Pht1;1(Y312D) variant conferred enhanced Pi transport when expressed in yeast cells. In contrast, mutation of Tyr 312 to Ala or Phe did not affect Pht1;1 transport kinetics. Our study demonstrates that modifications to the Pht1;1 higher-order structure affects Pi transport, suggesting that oligomerization may serve as a regulatory mechanism for modulating Pi uptake.
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA.
authors.forename: Elena B
authors.initials: EB
authors.lastname: Fontenot
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA.
authors.forename: Sandra Feuer
authors.initials: SF
authors.lastname: Ditusa
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Kato
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA.
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Olivier
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA.
authors.forename: Renee
authors.initials: R
authors.lastname: Dale
authors.affiliation: Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan, China.
authors.forename: Wei-Yi
authors.initials: WY
authors.lastname: Lin
authors.affiliation: Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan, China.
authors.forename: Tzyy-Jen
authors.initials: TJ
authors.lastname: Chiou
authors.affiliation: Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA.
authors.forename: Megan A
authors.initials: MA
authors.lastname: Macnaughtan
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA.
authors.forename: Aaron P
authors.initials: AP
authors.lastname: Smith
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D006706:Homeostasis; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D028061:Phosphate Transport Proteins / Q000235:genetics / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D055503:Protein Multimerization; D014443:Tyrosine / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; C520845:PHT1;1 protein, Arabidopsis; C494975:PT2 protein, Arabidopsis; D028061:Phosphate Transport Proteins; D010710:Phosphates; D010758:Phosphorus; D014443:Tyrosine
keywords: Arabidopsis; oligomerization; phosphate transporters; transporter activity