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

Sakiko Okumoto; Roberto Schmidt; Mechthild Tegeder; Wolf N Fischer; Doris Rentsch; Wolf B Frommer; Wolfgang Koch

doi:10.1074/jbc.M207730200

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

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

Sakiko Okumoto, Roberto Schmidt, Mechthild Tegeder, Wolf N Fischer, Doris Rentsch, Wolf B Frommer and Wolfgang Koch

The Journal of biological chemistry, Vol.277(47), pp.45338-45346

11/22/2002

DOI: https://doi.org/10.1074/jbc.M207730200

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https://hdl.handle.net/2376/104042

PMID: 12244056

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Abstract

Promoter Regions, Genetic

Arabidopsis - physiology

Arabidopsis Proteins - genetics

Introns - genetics

Seeds - metabolism

Plant Structures - metabolism

Tobacco - metabolism

Glucuronidase - metabolism

Exons - genetics

Amino Acid Transport Systems - metabolism

Recombinant Fusion Proteins - metabolism

Arabidopsis - genetics

Arabidopsis Proteins - metabolism

Yeasts - genetics

Amino Acid Transport Systems - classification

Glucuronidase - genetics

Tobacco - genetics

Arabidopsis - anatomy & histology

Cloning, Molecular

Amino Acid Transport Systems - genetics

Recombinant Fusion Proteins - genetics

Arabidopsis Proteins - classification

Tobacco - anatomy & histology

Yeasts - metabolism

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.

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Title: High affinity amino acid transporters specifically expressed in xylem parenchyma and developing seeds of Arabidopsis
Creators: Sakiko Okumoto - Plant Physiology, Zentrum für Molekularbiologie der Pflanzen (ZMBP), Auf der Morgenstelle 1, D-72076 Tübingen, Germany
Roberto Schmidt
Mechthild Tegeder
Wolf N Fischer
Doris Rentsch
Wolf B Frommer
Wolfgang Koch
Publication Details: The Journal of biological chemistry, Vol.277(47), pp.45338-45346
Academic Unit: Biological Sciences, School of
Publisher: United States
Identifiers: 99900546732301842
Language: English
Resource Type: Journal article