UNIGE document Scientific Article
previous document  unige:6808  next document
add to browser collection

Identification of a Ca(2+)-pectate binding site on an apoplastic peroxidase

Carpin, Sabine
Published in Plant Cell. 2001, vol. 13, no. 3, p. 511-20
Abstract An apoplastic isoperoxidase from zucchini (APRX) was shown to bind strongly to polygalacturonic acid in their Ca(2)+-induced conformation. By homology modeling, we were able to identify a motif of four clustered arginines (positions 117, 262, 268, and 271) that could be responsible for this binding. To verify the role of these arginine residues in the binding process, we prepared three mutants of APRX (M1, R117S; M2, R262Q/R268S; and M3, R262Q/R268S/R271Q). APRX and the three mutants were expressed as recombinant glycoproteins by the baculovirus-insect cell system. This procedure yielded four active enzymes with similar molecular masses that were tested for their ability to bind Ca(2)+-pectate. Recombinant wild-type APRX exhibited an affinity for the pectic structure comparable to that of the native plant isoperoxidase. The mutations impaired binding depending on the number of arginine residues that were replaced. M1 and M2 showed intermediate affinities, whereas M3 did not bind at all. This was demonstrated using an in vitro binding test and on cell walls of hypocotyl cross-sections. It can be concluded that APRX bears a Ca(2)+-pectate binding site formed by four clustered arginines. This site could ensure that APRX is properly positioned in cell walls, using unesterified domains of pectins as a scaffold.
Keywords Arginine/metabolismBinding Sites/geneticsCalcium-Binding Proteins/genetics/metabolismCell Wall/metabolismCucurbitaceae/cytology/genetics/metabolismElectrophoresisHypocotyl/cytologyModels, MolecularMutationPectins/metabolismPeroxidase/chemistry/genetics/metabolismPeroxidases/metabolismProtein ConformationStatic Electricity
PMID: 11251093
Full text
Article (Published version) (391 Kb) - document accessible for UNIGE members only Limited access to UNIGE
(ISO format)
CARPIN, Sabine et al. Identification of a Ca(2+)-pectate binding site on an apoplastic peroxidase. In: Plant Cell, 2001, vol. 13, n° 3, p. 511-20. doi: 10.2307/3871403 https://archive-ouverte.unige.ch/unige:6808

381 hits

1 download


Deposited on : 2010-06-08

Export document
Format :
Citation style :