Asparagus IRX9, IRX10, and IRX14A Are Components of an Active Xylan Backbone Synthase Complex that Forms in the Golgi Apparatus

Zeng, Wei; Lampugnani, Edwin R.; Picard, Kelsey L.; Song, Lili; Wu, Ai‐Min; Farion, Isabela M; Zhao, Jingzhe; Ford, Kris; Doblin, Monika S.; Bacic, Antony

doi:10.1104/pp.15.01919

Cited by 80 publications

(106 citation statements)

References 78 publications

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“…Taking advantage of these activities, RNA-seq was used to identify candidate genes involved in those activities. Further work using heterologous expression of asparagus genes and site-directed mutants have corroborated findings from Arabidopsis where (1) AoIRX9, AoIRX10, and AoIRX14 are core components of a Golgi-localized xylan synthesis protein complex, and (2) a functional glycosyltransferase active site is required for AoIRX10 and AoIRX14 catalytic activity (Zeng et al, 2016). …”

Section: Synthesis Of Wall Components Involved In Cell Wall Cross-linmentioning

confidence: 74%

Grass Cell Walls: A Story of Cross-Linking

2017

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Cell wall matrices are complex composites mainly of polysaccharides, phenolics (monomers and polymers), and protein. We are beginning to understand the synthesis of these major wall components individually, but still have a poor understanding of how cell walls are assembled into complex matrices. Valuable insight has been gained by examining intact components to understand the individual elements that make up plant cell walls. Grasses are a prominent group within the plant kingdom, not only for their important roles in global agriculture, but also for the complexity of their cell walls. Ferulate incorporation into grass cell wall matrices (C3 and C4 types) leads to a cross-linked matrix that plays a prominent role in the structure and utilization of grass biomass compared to dicot species. Incorporation of p-coumarates as part of the lignin structure also adds to the complexity of grass cell walls. Feruoylation results in a wall with individual hemicellulosic polysaccharides (arabinoxylans) covalently linked to each other and to lignin. Evidence strongly suggests that ferulates not only cross-link arabinoxylans, but may be important factors in lignification of the cell wall. Therefore, the distribution of ferulates on arabinoxylans could provide a means of structuring regions of the matrix with the incorporation of lignin and have a significant impact upon localized cell wall organization. The role of other phenolics in cell wall formation such as p-coumarates (which can have concentrations higher than ferulates) remains unknown. It is possible that p-coumarates assist in the formation of lignin, especially syringyl rich lignin. The uniqueness of the grass cell wall compared to dicot sepcies may not be so much in the gross composition of the wall, but how the distinctive individual components are organized into a functional wall matrix. These features are discussed and working models are provided to illustrate how changing the organization of feruoylation and p-coumaroylation could lead to differing cell wall properties.

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Section: Synthesis Of Wall Components Involved In Cell Wall Cross-linmentioning

confidence: 74%

Grass Cell Walls: A Story of Cross-Linking

2017

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“…If these highly abundant GT61_1 sequences directly act on the β-(1,4)-Xyl p backbone during biosynthesis, the extra copy of GT61_1 may be one reason for the increased frequency of backbone substitution in P. ovata . Several groups have been able to demonstrate the requirement of such a complex (Zeng et al , 2010, 2016; Jiang et al , 2016), despite the lack of evidence of GT61s being present. The temporal patterning of the Plantago putative xylan synthesis components, IRX10 and GT61, together with the well characterized CESAs, is at least suggestive of the synergistic action of multiple enzymes to produce the final heteroxylan structure.…”

Section: Discussionmentioning

confidence: 99%

Differences in glycosyltransferase family 61 accompany variation in seed coat mucilage composition inPlantagospp.

Phan¹,

Tucker²,

Khor³

et al. 2016

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“…Although microsomes from tobacco BY2 cells coexpressing Arabidopsis IRX9 and IRX14 showed xylan xylosyltransferase activities (Lee et al ., ), recombinant IRX9 and IRX14 proteins expressed in HEK293 cells did not (Urbanowicz et al ., ). It was proposed that IRX9 and IRX14 might serve as structural proteins for the assembly of xylan synthase complex (Ren et al ., ; Zeng et al ., ), but their exact functions remain to be examined. It is worth noting that the Arabidopsis irx10 irx10l double mutant still produces a low level of xylan (Brown et al ., ), indicating that IRX10 and IRX10L may not be the sole xylosyltransferases responsible for xylan backbone synthesis.…”

Section: Xylan Biosynthesismentioning

confidence: 99%

Secondary cell wall biosynthesis

2018

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Contents Summary1703I.Introduction1703II.Cellulose biosynthesis1705III.Xylan biosynthesis1709IV.Glucomannan biosynthesis1713V.Lignin biosynthesis1714VI.Concluding remarks1717Acknowledgements1717References1717 Summary Secondary walls are synthesized in specialized cells, such as tracheary elements and fibers, and their remarkable strength and rigidity provide strong mechanical support to the cells and the plant body. The main components of secondary walls are cellulose, xylan, glucomannan and lignin. Biochemical, molecular and genetic studies have led to the discovery of most of the genes involved in the biosynthesis of secondary wall components. Cellulose is synthesized by cellulose synthase complexes in the plasma membrane and the recent success of in vitro synthesis of cellulose microfibrils by a single recombinant cellulose synthase isoform reconstituted into proteoliposomes opens new doors to further investigate the structure and functions of cellulose synthase complexes. Most genes involved in the glycosyl backbone synthesis, glycosyl substitutions and acetylation of xylan and glucomannan have been genetically characterized and the biochemical properties of some of their encoded enzymes have been investigated. The genes and their encoded enzymes participating in monolignol biosynthesis and modification have been extensively studied both genetically and biochemically. A full understanding of how secondary wall components are synthesized will ultimately enable us to produce plants with custom‐designed secondary wall composition tailored to diverse applications.

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Asparagus IRX9, IRX10, and IRX14A Are Components of an Active Xylan Backbone Synthase Complex that Forms in the Golgi Apparatus

Cited by 80 publications

References 78 publications

Grass Cell Walls: A Story of Cross-Linking

Grass Cell Walls: A Story of Cross-Linking

Differences in glycosyltransferase family 61 accompany variation in seed coat mucilage composition inPlantagospp.

Secondary cell wall biosynthesis

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