Calmodulin as a Ca2+-sensing subunit of Arabidopsis cyclic nucleotide-gated channel complexes.
Fischer C, DeFalco TA, Karia P, Snedden WA, Moeder W, Yoshioka K, Dietrich P (2017)
Publication Language: English
Publication Status: Published
Publication Type: Journal article, Original article
Publication year: 2017
Journal
Book Volume: 58
Pages Range: 1208-1221
Journal Issue: 7
DOI: 10.1093/pcp/pcx052
Abstract
Ca2+ serves as a universal second messenger in eukaryotic signaling pathways, and the spatial and temporal patterns of Ca2+ concentration changes are determined by feedback and feed-forward regulation of the involved transport proteins. Cyclic nucleotide-gated channels (CNGCs) are Ca2+-permeable channels that interact with the ubiquitous Ca2+ sensor calmodulin (CaM). CNGCs interact with CaMs via diverse CaM-binding sites, including an IQ-motif, which has been identified in the C-termini of CNGC20 and CNGC12. Here we present a family-wide analysis of the IQ-motif from all 20 Arabidopsis CNGC isoforms. While most of their IQ-peptides interacted with conserved CaMs in yeast, some were unable to do so, despite high sequence conservation across the family. We showed that the CaM-binding ability of the IQ-motif is highly dependent on its proximal and distal vicinity. We determined that two alanine residues positioned N-terminal to the core IQ-sequence play a significant role in CaM-binding, and identified a polymorphism at this site that promoted or inhibited CaM-binding in yeast. Through detailed biophysical analysis of the CNGC2 IQ-motif we found that this polymorphism specifically affected the Ca2+-independent interactions with the C-lobe of CaM. This same polymorphism partially suppressed the induction of programmed cell death by CNGC11/12 in planta. Our work expands the model of CNGC regulation, and posits the C-lobe of apo-CaM is permanently associated with the channel at the N-terminal part of the IQ-domain. This mode allows CaM to function as a Ca2+-sensing regulatory subunit of the channel complex, providing a mechanism by which Ca2+ signals may be fine-tuned.
Authors with CRIS profile
Cornelia Fischer
Professur für Zellbiologie der Pflanzen
Petra Dietrich
Professur für Zellbiologie der Pflanzen
Involved external institutions
Canada (CA)How to cite
APA:
Fischer, C., DeFalco, T.A., Karia, P., Snedden, W.A., Moeder, W., Yoshioka, K., & Dietrich, P. (2017). Calmodulin as a Ca2+-sensing subunit of Arabidopsis cyclic nucleotide-gated channel complexes. Plant & cell physiology, 58(7), 1208-1221. https://dx.doi.org/10.1093/pcp/pcx052
MLA:
Fischer, Cornelia, et al. "Calmodulin as a Ca2+-sensing subunit of Arabidopsis cyclic nucleotide-gated channel complexes." Plant & cell physiology 58.7 (2017): 1208-1221.
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