The three members of the Arabidopsis Glycosyltransferase Family 92 are functional β-1,4-galactan synthases
Date
2018
Authors
Ebert, B.
Birdseye, D.
Liwanag, A.J.M.
Laursen, T.
Rennie, E.A.
Guo, X.
Catena, M.
Rautengarten, C.
Stonebloom, S.H.
Gluza, P.
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Journal Title
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Journal article
Citation
Plant and Cell Physiology, 2018; 59(12):2624-2636
Statement of Responsibility
Berit Ebert, Devon Birdseye, April J.M. Liwanag, Tomas Laursen, Emilie A. Rennie, Xiaoyuan Guo, Michela Catena, Carsten Rautengarten, Solomon H. Stonebloom, Pawel Gluza, Venkataramana R. Pidatala, Mathias C.F. Andersen, Roshan Cheetamun, Jenny C. Mortimer, Joshua L. Heazlewood, Antony Bacic, Mads H. Clausen, William G.T. Willats, and Henrik V. Scheller
Conference Name
Abstract
Pectin is a major component of primary cell walls and performs a plethora of functions crucial for plant growth, development and plant-defense responses. Despite the importance of pectic polysaccharides their biosynthesis is poorly understood. Several genes have been implicated in pectin biosynthesis by mutant analysis, but biochemical activity has been shown for very few. We used reverse genetics and biochemical analysis to study members of Glycosyltransferase Family 92 (GT92) in Arabidopsis thaliana. Biochemical analysis gave detailed insight into the properties of GALS1 (Galactan synthase 1) and showed galactan synthase activity of GALS2 and GALS3. All proteins are responsible for adding galactose onto existing galactose residues attached to the rhamnogalacturonan-I (RG-I) backbone. Significant GALS activity was observed with galactopentaose as acceptor but longer acceptors are favored. Overexpression of the GALS proteins in Arabidopsis resulted in accumulation of unbranched β-1, 4-galactan. Plants in which all three genes were inactivated had no detectable β-1, 4-galactan, and surprisingly these plants exhibited no obvious developmental phenotypes under standard growth conditions. RG-I in the triple mutants retained branching indicating that the initial Gal substitutions on the RG-I backbone are added by enzymes different from GALS.
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Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists 2018. This work is written by a US Government employee and is in the public domain in the US.