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Title: A group of Populus trichocarpa DUF231 proteins exhibit differential O-acetyltransferase activities toward xylan

Wood represents the most abundant biomass produced by plants and one of its major components is acetyl xylan. Acetylation in xylan can occur at O-2 or O-3 of a xylosyl residue, at both O-2 and O-3 of a xylosyl residue, and at O-3 of a xylosyl residue substituted at O-2 with glucuronic acid. Acetyltransferases responsible for the regiospecific acetylation of xylan in tree species have not yet been characterized. Here we report the biochemical characterization of twelve Populus trichocarpa DUF231-containing proteins, named PtrXOATs, for their roles in the regiospecific acetylation of xylan. The PtrXOAT genes were found to be differentially expressed in Populus organs and among them, PtrXOAT1, PtrXOAT2, PtrXOAT9 and PtrXOAT10 exhibited the highest level of expression in stems undergoing wood formation. Activity assays of recombinant proteins demonstrated that all twelve PtrXOAT proteins were able to transfer acetyl groups from acetyl CoA onto a xylohexaose acceptor with PtrXOAT1, PtrXOAT2, PtrXOAT3, PtrXOAT11 and PtrXOAT12 having the highest activity. Structural analysis of the PtrXOAT-catalyzed reaction products using 1H NMR spectroscopy revealed that PtrXOAT1, PtrXAOT2 and PtrXOAT3 mediated 2-O- and 3-O-monoacetylation and 2,3-di-O-acetylation of xylosyl residues and PtrXOAT11 and PtrXOAT12 only catalyzed 2-O- and 3-O-monoacetylation of xylosyl residues. Of the twelve PtrXOATs,more » only PtrXOAT9 and PtrXOAT10 were capable of transferring acetyl groups onto the O-3 position of 2-O-glucuronic acid-substituted xylosyl residues. Furthermore, when expressed in the Arabidopsis eskimo1 mutant, PtrXOAT1, PtrXAOT2 and PtrXOAT3 were able to rescue the defects in xylan acetylation. Together, these results demonstrate that the twelve PtrXOATs are acetyltransferases with different roles in xylan acetylation in P. trichocarpa.« less
Authors:
 [1] ;  [2] ; ORCiD logo [1] ;  [3]
  1. Univ. of Georgia, Athens, GA (United States). Dept. of Plant Biology
  2. Univ. of Georgia, Athens, GA (United States). Dept. of Chemistry
  3. Iowa State Univ., Ames, IA (United States)
Publication Date:
Grant/Contract Number:
FG02-03ER15415
Type:
Accepted Manuscript
Journal Name:
PLoS ONE
Additional Journal Information:
Journal Volume: 13; Journal Issue: 4; Journal ID: ISSN 1932-6203
Publisher:
Public Library of Science
Research Org:
Univ. of Georgia, Athens, GA (United States). Research Foundation, Inc.
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS
OSTI Identifier:
1499881

Zhong, Ruiqin, Cui, Dongtao, Ye, Zheng-Hua, and Zabotina, Olga A. A group of Populus trichocarpa DUF231 proteins exhibit differential O-acetyltransferase activities toward xylan. United States: N. p., Web. doi:10.1371/journal.pone.0194532.
Zhong, Ruiqin, Cui, Dongtao, Ye, Zheng-Hua, & Zabotina, Olga A. A group of Populus trichocarpa DUF231 proteins exhibit differential O-acetyltransferase activities toward xylan. United States. doi:10.1371/journal.pone.0194532.
Zhong, Ruiqin, Cui, Dongtao, Ye, Zheng-Hua, and Zabotina, Olga A. 2018. "A group of Populus trichocarpa DUF231 proteins exhibit differential O-acetyltransferase activities toward xylan". United States. doi:10.1371/journal.pone.0194532. https://www.osti.gov/servlets/purl/1499881.
@article{osti_1499881,
title = {A group of Populus trichocarpa DUF231 proteins exhibit differential O-acetyltransferase activities toward xylan},
author = {Zhong, Ruiqin and Cui, Dongtao and Ye, Zheng-Hua and Zabotina, Olga A.},
abstractNote = {Wood represents the most abundant biomass produced by plants and one of its major components is acetyl xylan. Acetylation in xylan can occur at O-2 or O-3 of a xylosyl residue, at both O-2 and O-3 of a xylosyl residue, and at O-3 of a xylosyl residue substituted at O-2 with glucuronic acid. Acetyltransferases responsible for the regiospecific acetylation of xylan in tree species have not yet been characterized. Here we report the biochemical characterization of twelve Populus trichocarpa DUF231-containing proteins, named PtrXOATs, for their roles in the regiospecific acetylation of xylan. The PtrXOAT genes were found to be differentially expressed in Populus organs and among them, PtrXOAT1, PtrXOAT2, PtrXOAT9 and PtrXOAT10 exhibited the highest level of expression in stems undergoing wood formation. Activity assays of recombinant proteins demonstrated that all twelve PtrXOAT proteins were able to transfer acetyl groups from acetyl CoA onto a xylohexaose acceptor with PtrXOAT1, PtrXOAT2, PtrXOAT3, PtrXOAT11 and PtrXOAT12 having the highest activity. Structural analysis of the PtrXOAT-catalyzed reaction products using 1H NMR spectroscopy revealed that PtrXOAT1, PtrXAOT2 and PtrXOAT3 mediated 2-O- and 3-O-monoacetylation and 2,3-di-O-acetylation of xylosyl residues and PtrXOAT11 and PtrXOAT12 only catalyzed 2-O- and 3-O-monoacetylation of xylosyl residues. Of the twelve PtrXOATs, only PtrXOAT9 and PtrXOAT10 were capable of transferring acetyl groups onto the O-3 position of 2-O-glucuronic acid-substituted xylosyl residues. Furthermore, when expressed in the Arabidopsis eskimo1 mutant, PtrXOAT1, PtrXAOT2 and PtrXOAT3 were able to rescue the defects in xylan acetylation. Together, these results demonstrate that the twelve PtrXOATs are acetyltransferases with different roles in xylan acetylation in P. trichocarpa.},
doi = {10.1371/journal.pone.0194532},
journal = {PLoS ONE},
number = 4,
volume = 13,
place = {United States},
year = {2018},
month = {4}
}