Molecular and Cell Biology
Ph.D., University of Munich
The cell walls of higher plants play pivotal roles during plant growth and development, and account for most of the newly synthesized terrestrial biomass. Accordingly, the study of cell wall synthesis is of considerable significance both from a basic and applied point of view. Our lab has taken a genetic approach to determine the roles of specific cell wall components, and to clone genes in cell wall biosynthetic pathways. We are pursuing two different strategies to accomplish our goals: (1) The characterization of cell wall mutants of the plant model system Arabidopsis thaliana, and (2) the identification of cell wall-related genes in Arabidopsis via sequence similarities to bacterial genes involved in polysaccharide synthesis. Using positional cloning approaches, we recently isolated the MUR2 and MUR3 genes of Arabidopsisencoding hemicellulose-specific fucosyl- and galactosyltransferases, respectively. Both MUR2 and MUR3 are members of multi-gene families which can now be characterized using the vast genomic resources and mutant collections available to the Arabidopsis community.
In a separate but related project, we have been pursuing the identification and characterization of nucleotide sugar interconversion enzymes, which generate the donor substrates for glycosyltransferases in plant cell wall synthesis. We recently reported the molecular cloning and biochemical characterization of a Golgi-localized UDP-D-xylose 4-epimerase in the de novo synthesis of UDP-L-arabinose, and a bifunctional UDP-sugar synthase that catalyzes the formation of the branched-chain sugar D-apiose. Our current work focuses on the characterization of plant enzymes in the the de novo synthesis of UDP-D-galacturonate and UDP-L-rhamnose, which are important precursors for the synthesis of pectic polysaccharides.
In the long term, we wish to understand the mechanisms by which plant cell wall material is being synthesized, and to create opportunities for the genetic manipulation of cell wall components for biotechnological purposes.
Mølhøj, M., Verma, R., and Reiter, W.-D. (2003) The biosynthesis of the branched-chain sugar D-apiose in plants: Functional cloning and characterization of a UDP-D-apiose/UDP-D-xylose synthase from Arabidopsis. Plant J. 35, 693-703.
Madson, M., Dunand, C., Li, X., Verma, R., Vanzin, G.F., Caplan, J., Shoue, D.A., Carpita, N.C., and Reiter, W.-D. (2003) The MUR3 gene of Arabidopsis thalianaencodes a xyloglucan galactosyltransferase that is evolutionarily related to animal exostosins. Plant Cell 15, 1662-1670.
To, J.P.C., Reiter, W.-D., and Gibson, S.I. (2003) Chloroplast biogenesis by Arabidopsis seedlings is impaired in the presence of exogenous glucose. Physiol. Plant. 118, 456-463.
Ryden, P., Sugimoto-Shirasu, K., Smith, A.C., Findlay, K., Reiter, W.-D., and McCann, M.C. (2003) Tensile properties of Arabidopsis cell walls depend on both a xyloglucan cross-linked microfibrillar network and rhamnogalacturonan II borate complexes. Plant Physiol. 132, 10331040.
Bonin, C.P., Freshour, G., Hahn, M.G., Vanzin, G.F., and Reiter, W.-D. (2003) The GMD1 and GMD2 genes of Arabidopsis thaliana encode isoforms of GDP-D-mannose 4,6-dehydratase with cell type-specific expression patterns. Plant Physiol. 132, 883-892.
Freshour, G., Bonin, C.P., Reiter, W.-D., Albersheim, P., Darvill, A.G., and Hahn, M.G. (2003) Distribution of fucose-containing xyloglucans in cell walls of the mur1 mutant of Arabidopsis thaliana. Plant Physiol. 131, 1602-1612.
Burget, E.G., Verma, R., Mølhøj, M., and Reiter, W.-D. (2003) The biosynthesis of L-arabinose in plants: Molecular cloning and characterization of a Golgi-localized UDP-D-xylose 4-epimerase encoded by the MUR4 gene of Arabidopsis. Plant Cell 15, 523-531.
Mulichak, A.M., Bonin, C.P., Reiter, W.-D., and Garavito, R.M. (2002) Structure of the MUR1 GDP-mannose 4,6-dehydratase from Arabidopsis thaliana: Implications for ligand binding and specificity. Biochemistry 41, 15578-15589.
Reiter, W.-D. (2002) Biosynthesis and properties of the plant cell wall. Curr. Opin. Plant Biol. 5, 536-542.
Vanzin, G.F., Madson, M., Carpita, N.C., Raikhel, N.V., Keegstra, K., and Reiter, W.D. (2002) The mur2 mutant of Arabidopsis thaliana lacks fucosylated xyloglucan because of a lesion in fucosyltransferase AtFUT1. Proc. Natl. Acad. Sci. USA 99, 3340-3345.
Reiter, W.-D. and Vanzin, G.F. (2001) Molecular genetics of nucleotide sugar interconversion pathways in plants. Plant Mol. Biol. 47, 95-113.
Bonin, C.P. and Reiter, W.-D. (2000) A bifunctional epimerase-reductase acts downstream of the MUR1 gene product and completes the de novo synthesis of GDP-L-fucose in Arabidopsis. Plant J. 21, 445-454.
Reiter, W.-D. (1998) The molecular analysis of cell wall components. Trends Plant Sci. 3, 2732.
Reiter, W.-D., Chapple, C., and Somerville, C.R. (1997) Mutants of Arabidopsis thaliana with altered cell wall polysaccharide composition. Plant J. 12, 335-345.
Bonin, C.P., Potter, I., Vanzin, G.F., and Reiter, W.-D. (1997) The MUR1 gene of Arabidopsis thaliana encodes an isoform of GDP-D-mannose-4,6-dehydratase, catalyzing the first step in the de novo synthesis of GDP-L-fucose. Proc. Natl. Acad. Sci. USA 94, 2085-2090.
Zablackis, E., York, W.S., Pauly, M., Hantus, S., Reiter, W.-D., Chapple, C.C.S., Albersheim, P., and Darvill, A. (1996) Substitution of L-fucose by L-galactose in cell walls of Arabidopsis mur1. Science 272, 1808-1810.
Reiter, W.-D., Chapple, C., and Somerville, C. (1993) Altered growth and cell walls in a fucose-deficient mutant of Arabidopsis. Science 261, 1032-1035