Curtis G. Wilkerson
Plant Cell Wall Biosynthesis
The plant cell wall provides shape and mechanical strength to the plant cell as well as modulating its interaction with the environment. While cellulose often comprises more than half of the mass of the cell wall many other compounds are important in the functioning of this structure. Many of these non-cellulosic components are complex carbohydrate molecules such as hemicelluloses and pectin. The exact nature of the contributions of each of these carbohydrate compounds to the functioning of the cell wall is not fully understood and is an area of active research. The biosynthesis of these carbohydrate molecules requires a large number of genes. This is due to the fact that unlike proteins and nucleic acids the synthesis of these polymers does not use a template. It is currently assumed that each type of glycosidic bond requires a separate enzyme; therefore, it is likely that hundreds of proteins are required for the synthesis of cell wall carbohydrates. An additionally complication is that while cellulose is made at the plasma membrane other carbohydrate components of the cell wall are synthesized in the Golgi apparatus. One class of cell wall carbohydrates synthesized in the Golgi apparatus is the hemicelluloses.
These molecules consist of a linear backbone made up of Β-glycosidic linkages decorated with side chains of various linkage types. The role of hemicelluloses may be to prevent the direct interaction of cellulose fibrils as the hemicelluloses coat the cellulose fibrils. The side chains of hemicelluloses prevent the tight interaction between hemicelluloses, which results in a soluble fiber. The alteration of these side chains after deposition in the wall allows the plant to control the properties of the wall. Different tissues within a plant have different hemcelluloses and various species of plants also differ in the hemicelluloses present in their cell walls. Currently, it is not clear what purpose this diversity of hemicellulose plays in wall function. In addition to wall function, hemicelluloses play important roles in human health and are an important consideration in the use of biomass to produce energy.
Our laboratory is interested in understanding the biosynthesis of hemicelluloses and their function in the cell wall. We are interested in three types of hemicelluloses; namely, xyloglucan, galactomannan and xylan. For each hemicellulose we have identified a plant tissue that produces a large quantity of one these hemicelluloses. These tissues are shown in figure 1. We are using deep sequencing of these tissues at multiple times points during the period of time that these tissues are synthesizing the particular hemicellulose. We are using the new generation of sequencing technologies to sequence millions of ESTs. This large data set has produce a number of candidates for genes involved in the biosynthesis of these hemicelluloses as well as genes involved in regulating the synthesis of these biosynthetic genes. We are in the process of using reverse genetics in arabidopsis to explore the function of these genes. We are also using heterologous expression of the biosynthetic gene candidates in yeast and bacterial to determine their function.
Jensen JK, Schultink A, Keegstra K, Wilkerson CG, Pauly M. 2012. RNA-seq analysis of developing nasturtium seeds (Tropaeolum majus): Identification and characterization of an additional galactosyltransferase involved in xyloglucan biosynthesis. Molecular Plant. 5:984-992.
Gille S, Cheng K, Skinner ME, Liepman AH, Wilkerson CG, Pauly M. 2011. Deep sequencing of voodoo lily (Amorphophallus konjac): an approach to identify relevant genes involved in the synthesis of the hemicellulose glucomannan. Planta 234:515-526.
Upham BL, Babica P, Park JS, Whitten DA, Wilkerson CG. 2011. Determining early signaling response to environmental toxicants using novel proteomic approaches. In Vitro Cellular & Developmental Biology-Animal:47 S42-S43.
Jensen JK, Kim H, Cocuron JC, Orler R, Ralph J, Wilkerson CG. 2011. The DUF579 domain containing proteins IRX15 and IRX15-L affect xylan synthesis in Arabidopsis. Plant J. 66:387-400.
Singh B, Avci U, Eichler Inwood SE, Grimson MJ, Landgraf J, Mohnen D, Sørensen I, Wilkerson CG, Willats WG, Haigler CH. 2009. A specialized outer layer of the primary cell wall joins elongating cotton fibers into tissue-like bundles. Plant Physiol. 150(2):684-99.
Ibdah M, Chen YT, Wilkerson CG, Pichersky E. 2009. An aldehyde oxidase in developing seeds of Arabidopsis converts benzaldehyde to benzoic Acid. Plant Physiol. 150(1):416-23.
Reumann S, Quan S, Aung K, Yang P, Manandhar-Shrestha K, Holbrook D, Linka N, Switzenberg R, Wilkerson CG, Weber AP, Olsen LJ, Hu J. 2009. In-depth proteome analysis of Arabidopsis leaf peroxisomes combined with in vivo subcellular targeting verification indicates novel metabolic and regulatory functions of peroxisomes. Plant Physiol. 150(1):125-43.
Bräutigam A, Shrestha RP, Whitten D, Wilkerson CG, Carr KM, Froehlich JE, Weber AP. 2008. Low-coverage massively parallel pyrosequencing of cDNAs enables proteomics in non-model species: comparison of a species-specific database generated by pyrosequencing with databases from related species for proteome analysis of pea chloroplast envelopes. J Biotechnol. 136(1-2):44-53.
Nagegowda DA, Gutensohn M, Wilkerson CG, Dudareva N. 2008. Two nearly identical terpene synthases catalyze the formation of nerolidol and linalool in snapdragon flowers. Plant J. 55(2):224-39.
Lu Y, Savage LJ, Ajjawi I, Imre KM, Yoder DW, Benning C, Dellapenna D, Ohlrogge JB, Osteryoung KW, Weber AP, Wilkerson CG, Last RL. 2008. New connections across pathways and cellular processes: industrialized mutant screening reveals novel associations between diverse phenotypes in Arabidopsis. Plant Physiol. 146(4):1482-500.
Koeduka T, Louie GV, Orlova I, Kish CM, Ibdah M, Wilkerson CG, Bowman ME, Baiga TJ, Noel JP, Dudareva N, Pichersky E. 2008. The multiple phenylpropene synthases in both Clarkia breweri and Petunia hybrida represent two distinct protein lineages. Plant J. 54(3):362-74.MORE