Rapid kinetics of calcium dissociation from plant calmodulin and calmodulin-like proteins and effect of target peptides

• Published in: Biochemical and biophysical research communications 2022-01, Vol.590, p.103-108
• Main Authors: Troilo, Francesca, Pedretti, Marco, Travaglini-Allocatelli, Carlo, Astegno, Alessandra, Di Matteo, Adele
• Format: Article
• Language: English
• Subjects: Arabidopsis - drug effects; Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Calcium; Calcium - metabolism; Calmodulin; Calmodulin - metabolism; Calmodulin-like proteins; Kinetics; Melitten - pharmacology; Melittin; Mutant Proteins - metabolism; Peptides - metabolism; RAD4; Rapid kinetics; SAC3B
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2021.12.077

Calcium (Ca2+) signaling represents a universal information code in plants, playing crucial roles spanning developmental processes to stress responses. Ca2+ signals are decoded into defined plant adaptive responses by different Ca2+ sensing proteins, including calmodulin (CaM) and calmodulin-like (CML) proteins. Although major advances have been achieved in describing how these Ca2+ decoding proteins interact and regulate downstream target effectors, the molecular details of these processes remain largely unknown. Herein, the kinetics of Ca2+ dissociation from a conserved CaM and two CML isoforms from A. thaliana has been studied by fluorescence stopped-flow spectroscopy. Kinetic data were obtained for the isolated Ca2+-bound proteins as well as for the proteins complexed with different target peptides. Moreover, the lobe specific interactions between the Ca2+ sensing proteins and their targets were characterized by using a panel of protein mutants deficient in Ca2+ binding at the N-lobe or C-lobe. Results were analyzed and discussed in the context of the Ca2+-decoding and Ca2+-controlled target binding mechanisms in plants. •Ca2+-binding proteins are instrumental in the control of Ca2+ signaling in plants.•The Arabidopsis genome harbours seven calmodulin and 50 calmodulin-like genes.•We measured Ca2+ dissociation rates from AtCaM1, AtCML7 and AtCML19 by rapid kinetics.•CaM and CML proteins show lobe specific Ca2+ dissociation kinetics.•Peptide binding impacts the kinetic properties of Ca2+-binding sites.