Linked Life Data

17944810

Source:http://linkedlifedata.com/resource/pubmed/id/17944810

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
2007-12-17
pubmed:abstractText
Previous studies using co-expression analysis have identified a large number of genes likely to be involved in secondary cell-wall formation. However, the function of very few of these genes is known. We have studied the cell-wall phenotype of irx7, irx8 and irx9, three previously described irregular xylem (irx) mutants, and irx14 and parvus-3, which we now show also to be secondary cell-wall mutants. All five mutants, which have mutations in genes encoding putative glycosyltransferases, exhibited large decreases in xylan. In addition, all five mutants were found to have the same specific defect in xylan structure, retaining MeGlcUA but lacking GlcUA side branches. Polysaccharide analysis by carbohydrate gel electrophoresis (PACE) was used to determine the xylan structure in Arabidopsis, and revealed that side branches are added to approximately one in every eight xylose residues. Interestingly, this ratio is constant in all the lines analysed despite the wide variation in xylan content and the absence of GlcUA branches. Xylanase digestion of xylan from wild-type plants released a short oligosaccharide sequence at the reducing end of the xylan chain. MALDI-TOF MS analysis indicated that this sequence of sugars was absent in xylan from irx7, irx8 and parvus-3 mutants, but was present in irx9 and irx14. This is consistent with previous NMR analysis of xylan from irx7, irx8 and irx9, and suggests that PARVUS may be involved in the synthesis of a xylan primer whereas IRX14 may be required to synthesize the xylan backbone. This hypothesis is supported by assays showing that irx9 and irx14 are both defective in incorporation of radiolabel from UDP (14)C-xylose. This study has important implications for both our understanding of xylan biosynthesis and the functional analysis of cell-wall biosynthesis genes.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0960-7412
pubmed:author
pubmed:issnType
Print
pubmed:volume
52
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1154-68
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Comparison of five xylan synthesis mutants reveals new insight into the mechanisms of xylan synthesis.
pubmed:affiliation
Faculty of Life Science, University of Manchester, Manchester M13 9PT, UK.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't