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Plant Physiol. 2017 Mar;173(3):1692-1708. doi: 10.1104/pp.16.01743. Epub 2017 Jan 23.

The IQD Family of Calmodulin-Binding Proteins Links Calcium Signaling to Microtubules, Membrane Subdomains, and the Nucleus.

Bürstenbinder K1,2,3, Möller B4,5,6, Plötner R4,5,6, Stamm G4,5,6, Hause G4,5,6, Mitra D4,5,6, Abel S4,5,6.

Author information

1
Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, 06120 Halle (Saale), Germany (K.B., R.P., G.S., D.M., S.A.); katharina.buerstenbinder@ipb-halle.de.
2
Institute of Computer Science (B.M.), Biocenter (G.H.), and Institute of Biochemistry and Biotechnology (S.A.), Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany; and katharina.buerstenbinder@ipb-halle.de.
3
Department of Plant Sciences, University of California, Davis, California 95616 (S.A.) katharina.buerstenbinder@ipb-halle.de.
4
Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, 06120 Halle (Saale), Germany (K.B., R.P., G.S., D.M., S.A.).
5
Institute of Computer Science (B.M.), Biocenter (G.H.), and Institute of Biochemistry and Biotechnology (S.A.), Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany; and.
6
Department of Plant Sciences, University of California, Davis, California 95616 (S.A.).

Abstract

Calcium (Ca2+) signaling and dynamic reorganization of the cytoskeleton are essential processes for the coordination and control of plant cell shape and cell growth. Calmodulin (CaM) and closely related calmodulin-like (CML) polypeptides are principal sensors of Ca2+ signals. CaM/CMLs decode and relay information encrypted by the second messenger via differential interactions with a wide spectrum of targets to modulate their diverse biochemical activities. The plant-specific IQ67 DOMAIN (IQD) family emerged as possibly the largest class of CaM-interacting proteins with undefined molecular functions and biological roles. Here, we show that the 33 members of the IQD family in Arabidopsis (Arabidopsis thaliana) differentially localize, using green fluorescent protein (GFP)-tagged proteins, to multiple and distinct subcellular sites, including microtubule (MT) arrays, plasma membrane subdomains, and nuclear compartments. Intriguingly, the various IQD-specific localization patterns coincide with the subcellular patterns of IQD-dependent recruitment of CaM, suggesting that the diverse IQD members sequester Ca2+-CaM signaling modules to specific subcellular sites for precise regulation of Ca2+-dependent processes. Because MT localization is a hallmark of most IQD family members, we quantitatively analyzed GFP-labeled MT arrays in Nicotiana benthamiana cells transiently expressing GFP-IQD fusions and observed IQD-specific MT patterns, which point to a role of IQDs in MT organization and dynamics. Indeed, stable overexpression of select IQD proteins in Arabidopsis altered cellular MT orientation, cell shape, and organ morphology. Because IQDs share biochemical properties with scaffold proteins, we propose that IQD families provide an assortment of platform proteins for integrating CaM-dependent Ca2+ signaling at multiple cellular sites to regulate cell function, shape, and growth.

PMID:
28115582
PMCID:
PMC5338658
DOI:
10.1104/pp.16.01743
[Indexed for MEDLINE]
Free PMC Article

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