TY - JOUR
T1 - The Three Members of the Arabidopsis Glycosyltransferase Family 92 are Functional β-1,4-Galactan Synthases
AU - Ebert, Berit
AU - Birdseye, Devon
AU - Liwanag, April J M
AU - Laursen, Tomas
AU - Rennie, Emilie A
AU - Guo, Xiaoyuan
AU - Catena, Michela
AU - Rautengarten, Carsten
AU - Stonebloom, Solomon H.
AU - Gluza, Pawel
AU - Pidatala, Venkataramana
AU - Andersen, Mathias C F
AU - Cheetamun, Roshan
AU - Mortimer, Jenny C
AU - Heazlewood, Joshua L
AU - Bacic, Antony
AU - Clausen, Mads H
AU - Willats, William G T
AU - Scheller, Henrik V.
PY - 2018
Y1 - 2018
N2 - 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 b-1, 4-galactan. Plants in which all three genes were inactivated had no detectable b-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.
AB - 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 b-1, 4-galactan. Plants in which all three genes were inactivated had no detectable b-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.
U2 - 10.1093/pcp/pcy180
DO - 10.1093/pcp/pcy180
M3 - Journal article
C2 - 30184190
SN - 0032-0781
VL - 59
SP - 2624
EP - 2636
JO - Plant and Cell Physiology
JF - Plant and Cell Physiology
IS - 12
ER -