(1,3;1,4)-β-Glucan Biosynthesis by the CSLF6 Enzyme: Position and Flexibility of Catalytic Residues Influence Product Fine Structure

George Dimitroff, Alan Little, Jelle Lahnstein, Julian G. Schwerdt, Vaibhav Srivastava, Vincent Bulone, Rachel A. Burton, Geoffrey B. Fincher

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)

Abstract

Cellulose synthase-like F6 (CslF6) genes encode polysaccharide synthases responsible for (1,3;1,4)-β-glucan biosynthesis in cereal grains. However, it is not clear how both (1,3)- and (1,4)-linkages are incorporated into a single polysaccharide chain and how the frequency and arrangement of the two linkage types that define the fine structure of the polysaccharide are controlled. Through transient expression in Nicotiana benthamiana leaves, two CSLF6 orthologs from different cereal species were shown to mediate the synthesis of (1,3;1,4)-β-glucans with very different fine structures. Chimeric cDNA constructs with interchanged sections of the barley and sorghum CslF6 genes were developed to identify regions of the synthase enzyme responsible for these differences. A single amino acid residue upstream of the TED motif in the catalytic region was shown to dramatically change the fine structure of the polysaccharide produced. The structural basis of this effect can be rationalized by reference to a homology model of the enzyme and appears to be related to the position and flexibility of the TED motif in the active site of the enzyme. The region and amino acid residue identified provide opportunities to manipulate the solubility of (1,3;1,4)-β-glucan in grains and vegetative tissues of the grasses and, in particular, to enhance the solubility of dietary fibers that are beneficial to human health.

Original languageEnglish
Pages (from-to)2054-2061
Number of pages8
JournalBiochemistry
Volume55
Issue number13
DOIs
Publication statusPublished - 5 Apr 2016
Externally publishedYes

Keywords

  • Carbohydrates
  • Chemical structure
  • Monomers
  • Peptides and proteins
  • Plant derived food

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