TY - JOUR

T1 - An oligogalacturonide-derived molecular probe demonstrates the dynamics of calcium-mediated pectin complexation in cell walls of tip-growing structures

AU - Mravec, Jozef

AU - Kracun, Stjepan Kresimir

AU - Rydahl, Maja Gro

AU - Westereng, Bjørge

AU - Pontiggia, Daniela

AU - De Lorenzo, Giulia

AU - Domozych, David S.

AU - Willats, William George Tycho

N1 - © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

PY - 2017

Y1 - 2017

N2 - 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 (OGs) 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.

AB - 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 (OGs) 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.

KW - Journal Article

U2 - 10.1111/tpj.13574

DO - 10.1111/tpj.13574

M3 - Journal article

C2 - 28419587

VL - 91

SP - 534

EP - 546

JO - Plant Journal

JF - Plant Journal

SN - 0960-7412

IS - 3

ER -