Dataset Information

Functional roles of rice glycosyltransferase family GT43 in xylan biosynthesis.

ABSTRACT: Xylan is the major hemicellulose present in both primary and secondary cell walls of rice vegetative tissues. Since xylan is one of the factors contributing to biomass recalcitrance, understanding how xylan is synthesized in rice will potentially provide tools to modify grass biomass composition better suited for biofuel production. Studies of xylan biosynthesis in Arabidopsis have revealed that family GT43 glycosyltransferases, which form 2 functionally nonredundant groups, IRX9/IRX9 homolog and IRX14/IRX14 homolog, are required for xylan backbone elongation. The rice genome harbors 10 genes encoding family GT43 members and it is currently unknown whether they are all involved in xylan biosynthesis. In this report, we performed biochemical analysis of xylan xylosyltransferase activity in rice stem microsomes and investigated the roles of 4 representative rice GT43 members, OsGT43A (LOC_Os05 g03174), OsGT43E (LOC_Os05 g48600), OsGT43H (LOC_Os04 g01280), and OsGT43J (LOC_Os06 g47340), in xylan biosynthesis. OsGT43 proteins were shown to be localized in the Golgi, where xylan biosynthesis occurs. Complementation analysis by expression of OsGT43s in Arabidopsis irx9 and irx14 mutants demonstrated that OsGT43A and OsGT43E but not OsGT43H and OsGT43J were able to rescue the mutant phenotypes conferred by the irx9 mutation, including defective stem mechanical strength, vessel morphology, xylan content, GlcA side chains, xylan chain length, and xylosyltransferase activity. On the other hand, OsGT43J but not OsGT43A, OsGT43E, and OsGT43H restored the defective xylan phenotype in the irx14 mutant. These results indicate that the rice GT43 family evolved to retain the involvement of 2 functionally nonredundant groups, OsGT43A and OsGT43E (IRX9 homologs) vs. OsGT43J (an IRX14 homolog), in xylan backbone biosynthesis.

SUBMITTER: Lee C

PROVIDER: S-EPMC4091335 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Functional roles of rice glycosyltransferase family GT43 in xylan biosynthesis.

Lee Chanhui C Teng Quincy Q Zhong Ruiqin R Yuan Youxi Y Ye Zheng-Hua ZH

Plant signaling & behavior 20140213 1

Xylan is the major hemicellulose present in both primary and secondary cell walls of rice vegetative tissues. Since xylan is one of the factors contributing to biomass recalcitrance, understanding how xylan is synthesized in rice will potentially provide tools to modify grass biomass composition better suited for biofuel production. Studies of xylan biosynthesis in Arabidopsis have revealed that family GT43 glycosyltransferases, which form 2 functionally nonredundant groups, IRX9/IRX9 homolog an ...[more]

PMID: 24525904

Similar Datasets

Project description:Xylan is the most abundant un-cellulosic polysaccharides of plant cell walls. Much progress in xylan biosynthesis has been gained in the model plant species Arabidopsis. Two homologous pairs Irregular Xylem 9 (IRX9)/9L and IRX14/14L from glycosyltransferase (GT) family 43 have been proved to play crucial roles in xylan backbone biosynthesis. However, xylan biosynthesis in grass such as Miscanthus remains poorly understood.We characterized seven GT43 members in M. lutarioriparius, a promising bioenergy crop. Quantitative real-time RT-PCR (qRT-PCR) analysis revealed that the expression of MlGT43 genes was ubiquitously detected in the tissues examined. In-situ hybridization demonstrated that MlGT43A-B and MlGT43F-G were specifically expressed in sclerenchyma, while MlGT43C-E were expressed in both sclerenchyma and parenchyma. All seven MlGT43 proteins were localized to Golgi apparatus. Overexpression of MlGT43A-E but not MlGT43F and MlGT43G in Arabidopsis irx9 fully or partially rescued the mutant defects, including morphological changes, collapsed xylem and increased xylan contents, whereas overexpression of MlGT43F and MlGT43G but not MlGT43A-E complemented the defects of irx14, indicating that MlGT43A-E are functional orthologues of IRX9, while MlGT43F and MlGT43G are functional orthologues of IRX14. However, overexpression of all seven MlGT43 genes could not rescue the mucilage defects of irx14 seeds. Furthermore, transient transactivation analyses of MlGT43A-E reporters demonstrated that MlGT43A and MlGT43B but not MlGT43C-E were differentially activated by MlSND1, MlMYB46 or MlVND7.The results demonstrated that all seven MlGT43s are functionally conserved in xylan biosynthesis during secondary cell wall formation but diversify in seed coat mucilage xylan biosynthesis. The results obtained provide deeper insight into xylan biosynthesis in grass, which lay the foundation for genetic modification of grass cell wall components and structure to better suit for next-generation biofuel production.

Project description:BackgroundXylan is one of the most abundant hemicelluloses and can crosslink cellulose and lignin to increase the stability of cell walls. A number of genes encoding glycosyltransferases play vital roles in xylan biosynthesis in plants, such as those of the GT43 family. However, little is known about glycosyltransferases in bamboo, especially woody bamboo which is a good substitute for timber.ResultsA total of 17 GT43 genes (PeGT43-1 ~ PeGT43-17) were identified in the genome of moso bamboo (Phyllostachys edulis), which belong to three subfamilies with specific motifs. The phylogenetic and collinearity analyses showed that PeGT43s may have undergone gene duplication, as a result of collinearity found in 12 pairs of PeGT43s, and between 17 PeGT43s and 10 OsGT43s. A set of cis-acting elements such as hormones, abiotic stress response and MYB binding elements were found in the promoter of PeGT43s. PeGT43s were expressed differently in 26 tissues, among which the highest expression level was found in the shoots, especially in the rapid elongation zone and nodes. The genes coexpressed with PeGT43s were annotated as associated with polysaccharide metabolism and cell wall biosynthesis. qRT-PCR results showed that the coexpressed genes had similar expression patterns with a significant increase in 4.0 m shoots and a peak in 6.0 m shoots during fast growth. In addition, the xylan content and structural polysaccharide staining intensity in bamboo shoots showed a strong positive correlation with the expression of PeGT43s. Yeast one-hybrid assays demonstrated that PeMYB35 could recognize the 5' UTR/promoter of PeGT43-5 by binding to the SMRE cis-elements.ConclusionsPeGT43s were found to be adapted to the requirement of xylan biosynthesis during rapid cell elongation and cell wall accumulation, as evidenced by the expression profile of PeGT43s and the rate of xylan accumulation in bamboo shoots. Yeast one-hybrid analysis suggested that PeMYB35 might be involved in xylan biosynthesis by regulating the expression of PeGT43-5 by binding to its 5' UTR/promoter. Our study provides a comprehensive understanding of PeGT43s in moso bamboo and lays a foundation for further functional analysis of PeGT43s for xylan biosynthesis during rapid growth.

Project description:Xylans constitute the main non-cellulosic polysaccharide in the secondary cell walls of plants. Several genes predicted to encode glycosyltransferases are required for the synthesis of the xylan backbone even though it is a homopolymer consisting entirely of β-1,4-linked xylose residues. The putative glycosyltransferases IRX9, IRX14, and IRX10 (or the paralogs IRX9L, IRX14L, and IRX10L) are required for xylan backbone synthesis in Arabidopsis. To investigate the function of IRX9, IRX9L, and IRX14, we identified amino acid residues known to be essential for catalytic function in homologous mammalian proteins and generated modified cDNA clones encoding proteins where these residues would be mutated. The mutated gene constructs were used to transform wild-type Arabidopsis plants and the irx9 and irx14 mutants, which are deficient in xylan synthesis. The ability of the mutated proteins to complement the mutants was investigated by measuring growth, determining cell wall composition, and microscopic analysis of stem cross-sections of the transgenic plants. The six different mutated versions of IRX9 and IRX9-L were all able to complement the irx9 mutant phenotype, indicating that residues known to be essential for glycosyltransferases function in homologous proteins are not essential for the biological function of IRX9/IRX9L. Two out of three mutated IRX14 complemented the irx14 mutant, including a mutant in the predicted catalytic amino acid. A IRX14 protein mutated in the substrate-binding DxD motif did not complement the irx14 mutant. Thus, substrate binding is important for IRX14 function but catalytic activity may not be essential for the function of the protein. The data indicate that IRX9/IRX9L have an essential structural function, most likely by interacting with the IRX10/IRX10L proteins, but do not have an essential catalytic function. Most likely IRX14 also has primarily a structural role, but it cannot be excluded that the protein has an important enzymatic activity.

Project description:Lignocellulosic biomass, encompassing cellulose, lignin and hemicellulose in plant secondary cell walls (SCWs), is the most abundant source of renewable materials on earth. Currently, fast-growing woody dicots such as Eucalyptus and Populus trees are major lignocellulosic (wood fiber) feedstocks for bioproducts such as pulp, paper, cellulose, textiles, bioplastics and other biomaterials. Processing wood for these products entails separating the biomass into its three main components as efficiently as possible without compromising yield. Glucuronoxylan (xylan), the main hemicellulose present in the SCWs of hardwood trees carries chemical modifications that are associated with SCW composition and ultrastructure, and affect the recalcitrance of woody biomass to industrial processing. In this review we highlight the importance of xylan properties for industrial wood fiber processing and how gaining a greater understanding of xylan biosynthesis, specifically xylan modification, could yield novel biotechnology approaches to reduce recalcitrance or introduce novel processing traits. Altering xylan modification patterns has recently become a focus of plant SCW studies due to early findings that altered modification patterns can yield beneficial biomass processing traits. Additionally, it has been noted that plants with altered xylan composition display metabolic differences linked to changes in precursor usage. We explore the possibility of using systems biology and systems genetics approaches to gain insight into the coordination of SCW formation with other interdependent biological processes. Acetyl-CoA, s-adenosylmethionine and nucleotide sugars are precursors needed for xylan modification, however, the pathways which produce metabolic pools during different stages of fiber cell wall formation still have to be identified and their co-regulation during SCW formation elucidated. The crucial dependence on precursor metabolism provides an opportunity to alter xylan modification patterns through metabolic engineering of one or more of these interdependent pathways. The complexity of xylan biosynthesis and modification is currently a stumbling point, but it may provide new avenues for woody biomass engineering that are not possible for other biopolymers.

Dataset Information

Functional roles of rice glycosyltransferase family GT43 in xylan biosynthesis.

Publications

Functional roles of rice glycosyltransferase family GT43 in xylan biosynthesis.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets