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Functional identification of Arabidopsis ATSIP2 (At3g57520) as an alkaline α-galactosidase with a substrate specificity for raffinose and an apparent sink-specific expression patter


Peters, S; Egert, A; Stieger, B; Keller, F (2010). Functional identification of Arabidopsis ATSIP2 (At3g57520) as an alkaline α-galactosidase with a substrate specificity for raffinose and an apparent sink-specific expression patter. Plant & Cell Physiology, 51(10):1815-1819.

Abstract

Arabidopsis ATSIP2 has recently been suggested to be a raffinose synthase gene. However, it has high amino acid identity to functionally characterized alkaline α-galactosidases from Cucumis melo and Zea mays. Using the Sf9 insect cell expression system, we demonstrate that recombinant ATSIP2 is a genuine alkaline α-galactosidase with a distinct substrate specificity for raffinose, and not a raffinose synthase. A β-glucuronidase reporter construct using the ATSIP2 promoter shows that ATSIP2 is strongly expressed in sink tissues of Arabidopsis, i.e. sink leaves and non-xylem parts of the root stele, suggesting a physiological function in raffinose phloem unloading.

Arabidopsis ATSIP2 has recently been suggested to be a raffinose synthase gene. However, it has high amino acid identity to functionally characterized alkaline α-galactosidases from Cucumis melo and Zea mays. Using the Sf9 insect cell expression system, we demonstrate that recombinant ATSIP2 is a genuine alkaline α-galactosidase with a distinct substrate specificity for raffinose, and not a raffinose synthase. A β-glucuronidase reporter construct using the ATSIP2 promoter shows that ATSIP2 is strongly expressed in sink tissues of Arabidopsis, i.e. sink leaves and non-xylem parts of the root stele, suggesting a physiological function in raffinose phloem unloading.

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Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Plant and Microbial Biology
04 Faculty of Medicine > University Hospital Zurich > Clinic for Clinical Pharmacology and Toxicology
Dewey Decimal Classification:610 Medicine & health
580 Plants (Botany)
Language:English
Date:2010
Deposited On:02 Dec 2010 16:28
Last Modified:05 Apr 2016 14:16
Publisher:Oxford University Press
ISSN:0032-0781
Additional Information:This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Plant & Cell Physiology following peer review. The definitive publisher-authenticated version Plant & Cell Physiology 2010, 51(10):1815-1819 is available online at: http://pcp.oxfordjournals.org/content/51/10/1815.long
Publisher DOI:10.1093/pcp/pcq127
PubMed ID:20739305
Permanent URL: http://doi.org/10.5167/uzh-36234

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