Journal Article

The <i>PARVUS</i> Gene is Expressed in Cells Undergoing Secondary Wall Thickening and is Essential for Glucuronoxylan Biosynthesis

Chanhui Lee, Ruiqin Zhong, Elizabeth A. Richardson, David S. Himmelsbach, Brooks T. McPhail and Zheng-Hua Ye

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 48, issue 12, pages 1659-1672
Published in print December 2007 | ISSN: 0032-0781
Published online December 2007 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcm155
The PARVUS Gene is Expressed in Cells Undergoing Secondary Wall Thickening and is Essential for Glucuronoxylan Biosynthesis

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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Xylan, cellulose and lignin are the three major components of secondary walls in wood, and elucidation of the biosynthetic pathway of xylan is of importance for potential modification of secondary wall composition to produce wood with improved properties. So far, three Arabidopsis glycosyltransferases, FRAGILE FIBER8, IRREGULAR XYLEM8 and IRREGULAR XYLEM9, have been implicated in glucuronoxylan (GX) biosynthesis. In this study, we demonstrate that PARVUS, which is a member of family GT8, is required for the biosynthesis of the tetrasaccharide primer sequence, β-d-Xyl-(1 → 3)-α-l-Rha-(1 → 2)-α-d-GalA-(1 → 4)-d-Xyl, located at the reducing end of GX. The PARVUS gene is expressed during secondary wall biosynthesis in fibers and vessels, and its encoded protein is predominantly localized in the endoplasmic reticulum. Mutation of the PARVUS gene leads to a drastic reduction in secondary wall thickening and GX content. Structural analysis of GX using 1H-nuclear magnetic resonance (NMR) spectroscopy revealed that the parvus mutation causes a loss of the tetrasaccharide primer sequence at the reducing end of GX and an absence of glucuronic acid side chains in GX. Activity assay showed that the xylan xylosyltransferase and glucuronyltransferase activities were not affected in the parvus mutant. Together, these findings implicate a possible role for PARVUS in the initiation of biosynthesis of the GX tetrasaccharide primer sequence and provide novel insights into the mechanisms of GX biosynthesis.

Keywords: Arabidopsis; Glucuronoxylan biosynthesis; Glycosyltransferase; PARVUS; Secondary wall biosynthesis

Journal Article.  8173 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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