A gene from the cellulose synthase-like C family encodes a beta-1,4 glucan synthase.
Despite the central role of xyloglucan (XyG) in plant cell wall structure and function, important details of its biosynthesis are not understood. To identify the gene(s) responsible for synthesizing the beta-1,4 glucan backbone of XyG, we exploited a property of nasturtium (Tropaeolum majus) seed development. During the last stages of nasturtium seed maturation, a large amount of XyG is deposited as a reserve polysaccharide. A cDNA library was produced from mRNA isolated during the deposition of XyG, and partial sequences of 10,000 cDNA clones were determined. A single member of the C subfamily from the large family of cellulose synthase-like (CSL) genes was found to be overrepresented in the cDNA library. Heterologous expression of this gene in the yeast Pichia pastoris resulted in the production of a beta-1,4 glucan, confirming that the CSLC protein has glucan synthase activity. The Arabidopsis CSLC4 gene, which is the gene with the highest sequence similarity to the nasturtium CSL gene, is coordinately expressed with other genes involved in XyG biosynthesis. These and other observations provide a compelling case that the CSLC gene family encode proteins that synthesize the XyG backbone.
Cocuron
Jean-Christophe
JC
Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA.
Lerouxel
Olivier
O
Drakakaki
Georgia
G
Alonso
Ana P
AP
Liepman
Aaron H
AH
Keegstra
Kenneth
K
Raikhel
Natasha
N
Wilkerson
Curtis G
CG
D017360:Arabidopsis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D050260:Carbohydrate Metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D017343:Genes, Plant; D005964:Glucosyltransferases / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D010843:Pichia / Q000235:genetics; D021381:Protein Transport; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds / Q000254:growth & development; D012995:Solubility; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014026:Nicotiana / Q000166:cytology / Q000378:metabolism; D014158:Transcription, Genetic; D032388:Tropaeolum / Q000201:enzymology* / Q000235:genetics*
D029681:Arabidopsis Proteins; D005964:Glucosyltransferases; C478648:cellulose synthase