Premium
An oligogalacturonide‐derived molecular probe demonstrates the dynamics of calcium‐mediated pectin complexation in cell walls of tip‐growing structures
Author(s) -
Mravec Jozef,
Kračun Stjepan K.,
Rydahl Maja G.,
Westereng Bjørge,
Pontiggia Daniela,
De Lorenzo Giulia,
Domozych David S.,
Willats William G. T.
Publication year - 2017
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13574
Subject(s) - cell wall , divalent , chemistry , calcium , biophysics , pectin , biochemistry , cell , elongation , plant cell , endogeny , organic chemistry , biology , materials science , ultimate tensile strength , gene , metallurgy
Summary Pectic homogalacturonan ( HG ) is one of the main constituents of plant cell walls. When processed to low degrees of esterification, HG can form complexes with divalent calcium ions. These macromolecular structures (also called egg boxes) play an important role in determining the biomechanics of cell walls and in mediating cell‐to‐cell adhesion. Current immunological methods enable only steady‐state detection of egg box formation in situ . Here we present a tool for efficient real‐time visualisation of available sites for HG crosslinking within cell wall microdomains. Our approach is based on calcium‐mediated binding of fluorescently tagged long oligogalacturonides ( OG s) with endogenous de‐esterified HG . We established that more than seven galacturonic acid residues in the HG chain are required to form a stable complex with endogenous HG through calcium complexation in situ , confirming a recently suggested thermodynamic model. Using defined carbohydrate microarrays, we show that the long OG probe binds exclusively to HG that has a very low degree of esterification and in the presence of divalent ions. We used this probe to study real‐time dynamics of HG during elongation of Arabidopsis pollen tubes and root hairs. Our results suggest a different spatial organisation of incorporation and processing of HG in the cell walls of these two tip‐growing structures.