High affinity amino acid transporters specifically expressed in xylem parenchyma and developing seeds of Arabidopsis

Okumoto, Sakiko; Schmidt, Roberto; Tegeder, Mechthild; Fischer, Wolf N.; Rentsch, Doris; Frommer, Wolf B.; Koch, Wolfgang (2002). High affinity amino acid transporters specifically expressed in xylem parenchyma and developing seeds of Arabidopsis. Journal of biological chemistry, 277(47), pp. 45338-45346. American Society for Biochemistry and Molecular Biology 10.1074/jbc.M207730200

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Arabidopsis amino acid transporters (AAPs) show individual temporal and spatial expression patterns. A new amino acid transporter, AAP8 was isolated by reverse transcription-PCR. Growth and transport assays in comparison to AAP1-5 characterize AAP8 and AAP6 as high affinity amino acid transport systems from Arabidopsis. Histochemical promoter-beta-glucuronidase (GUS) studies identified AAP6 expression in xylem parenchyma, cells requiring high affinity transport due to the low amino acid concentration in xylem sap. AAP6 may thus function in uptake of amino acids from xylem. Histochemical analysis of AAP8 revealed stage-dependent expression in siliques and developing seeds. Thus AAP8 is probably responsible for import of organic nitrogen into developing seeds. The only missing transporter of the family AAP7 was nonfunctional in yeast with respect to amino acid transport, and expression was not detectable. Therefore, AAP6 and -8 are the only members of the family able to transport aspartate with physiologically relevant affinity. AAP1, -6 and -8 are the closest AAP paralogs. Although AAP1 and AAP8 originate from a duplicated region on chromosome I, biochemical properties and expression pattern diverged. Overlapping substrate specificities paired with individual properties and expression patterns point to specific functions of each of the AAP genes in nitrogen distribution rather than to mere redundancy.

Item Type:	Journal Article (Original Article)
Division/Institute:	08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS) > Molecular Plant Physiology 08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS)
UniBE Contributor:	Rentsch, Doris
Subjects:	500 Science > 580 Plants (Botany)
ISSN:	0021-9258
Publisher:	American Society for Biochemistry and Molecular Biology
Language:	English
Submitter:	Peter Alfred von Ballmoos-Haas
Date Deposited:	06 Jun 2014 08:20
Last Modified:	05 Dec 2022 14:34
Publisher DOI:	10.1074/jbc.M207730200
URI:	https://boris.unibe.ch/id/eprint/53323