Deficiency of adenosine kinase activity affects the degree of pectin methyl-esterification in cell walls of Arabidopsis thaliana.
Pectin methyl-esterification is catalysed by S-adenosyl-L: -methionine (SAM)-dependent methyltransferases. As deficiency in adenosine kinase (ADK; EC 2.7.1.20) activity impairs SAM recycling and utilization, we investigated the relationship between ADK-deficiency and the degree of pectin methyl-esterification in cell walls of Arabidopsis thaliana. The distribution patterns of epitopes associated with methyl-esterified homogalacturonan in leaves and hypocotyls of wild-type (WT) and ADK-deficient plants were examined using immunolocalization and biochemical techniques. JIM5 and LM7 epitopes, characteristic of low esterified pectins, were more irregularly distributed along the cell wall in ADK-deficient plants than in WT cell walls. In addition, epitopes recognized by JIM7, characteristic of pectins with a higher degree of methyl-esterification, were less abundant in ADK-deficient leaves and hypocotyls. Since de-esterified pectins have enhanced adhesion properties, we propose that the higher abundance and the altered distribution of low methyl-esterified pectin in ADK-deficient cell walls lead to the leaf shape abnormalities observed in these plants.
Pereira
L A R
LA
Department of Biology, University of Waterloo, Waterloo, ON, Canada.
Schoor
S
S
Goubet
F
F
Dupree
P
P
Moffatt
B A
BA
D000248:Adenosine Kinase / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology*; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D002473:Cell Wall / Q000201:enzymology*; D004951:Esterification; D005455:Fluorescent Antibody Technique
D000248:Adenosine Kinase; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase