Arabidopsis ANTR1 is a thylakoid Na+-dependent phosphate transporter: functional characterization in Escherichia coli.
In this study, the putative anion transporter 1 (ANTR1) from Arabidopsis thaliana was shown to be localized to the chloroplast thylakoid membrane by Western blotting with two different peptide-specific antibodies. ANTR1 is homologous to the type I of mammalian Na+-dependent inorganic phosphate (Pi) transporters. The function of ANTR1 as a Na+-dependent Pi transporter was demonstrated by heterologous expression and uptake of radioactive Pi into Escherichia coli cells. The expression of ANTR1 conferred increased growth rates to the transformed cells and stimulated Pi uptake in a pH- and Na+-dependent manner as compared with the control cells. Among various tested effectors, Pi was the preferred substrate. Although it competed with the uptake of Pi, glutamate was not transported by ANTR1 into E. coli. In relation to its function as a Pi transporter, several physiological roles for ANTR1 in the thylakoid membrane are proposed, such as export of Pi produced during nucleotide metabolism in the thylakoid lumen back to the chloroplast stroma and balance of the trans-thylakoid H+ electrochemical gradient storage.
Pavón
Lorena Ruiz
LR
Division of Molecular Genetics, Department of Physics, Chemistry, and Biology, Linköping University, SE-581 83 Linköping, Sweden.
Lundh
Fredrik
F
Lundin
Björn
B
Mishra
Arti
A
Persson
Bengt L
BL
Spetea
Cornelia
C
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D004926:Escherichia coli / Q000378:metabolism*; D005786:Gene Expression Regulation; D018506:Gene Expression Regulation, Plant; D006863:Hydrogen-Ion Concentration; D026901:Membrane Transport Proteins / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D028061:Phosphate Transport Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D018521:Plant Physiological Phenomena; D017386:Sequence Homology, Amino Acid; D012964:Sodium / Q000378:metabolism*; D020524:Thylakoids / Q000378:metabolism*
C529796:ANTR-1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D026901:Membrane Transport Proteins; D028061:Phosphate Transport Proteins; D012964:Sodium