More Like this

1. Resting cytosol Ca2+ level maintained by Ca2+ pumps affects environmental responses in Arabidopsis

   https://doi.org/10.1093/plphys/kiad047  

   Li, Zhan; Harper, Jeffrey F.; Weigand, Chrystle; Hua, Jian (January 2023, Plant Physiology)

   Abstract Calcium ion transporting systems control cytosol Ca2+ levels ([Ca2+]cyt) and generate transient calcium (Ca2+) signatures that are key to environmental responses. Here, we report an impact of resting [Ca2+]cyt on plants from the functional study of calmodulin-regulated Ca2+ pumps or Ca2+-ATPases in Arabidopsis (Arabidopsis thaliana). The plasma membrane-localized pumps ACA8 (autoinhibited Ca2+-ATPase) and ACA10, as well as the vacuole-localized pumps ACA4 and ACA11, were critical in maintaining low resting [Ca2+]cyt and essential for plant survival under chilling and heat-stress conditions. Their loss-of-function mutants aca8 aca10 and aca4 aca11 had autoimmunity at normal temperatures, and this deregulated immune activation was enhanced by low temperature, leading to chilling lethality. Furthermore, these mutants showed an elevated resting [Ca2+]cyt, and a reduction of external Ca2+ lowered [Ca2+]cyt and repressed their autoimmunity and cold susceptibility. The aca8 aca10 and the aca4 aca11 mutants were also susceptible to heat, likely resulting from more closed stomata and higher leaf surface temperature than the wild type. These observations support a model in which the regulation of resting [Ca2+]cyt is critical to how plants regulate biotic and abiotic responses. 

   more » « less
2. Resting cytosol Ca2+ level is maintained by calmodulin regulated Ca2+ pumps and affects environmental responses in Arabidopsis

   Li Z, Harper JF (April 2023, Plant physiology)

   Calcium ion transporting systems control cytosol Ca2+ levels ([Ca2+]cyt) and generate transient calcium (Ca2+) signatures which are considered to be key to environmental responses. Here, we report an impact of resting [Ca2+]cyt on plants from the functional study of calmodulin regulated Ca2+ pumps or Ca2+-ATPases in Arabidopsis thaliana. The plasma membrane localized pumps ACA8 and ACA10 as well as the vacuole localized pumps ACA4 and ACA11 are found to be critical in maintaining low resting [Ca2+]cyt and be essential for plant survival under chilling and heat-stress conditions. Their loss-of-function mutants aca8 aca10 and aca4 aca11 have autoimmunity at normal temperature, and this deregulated immune activation is enhanced by low temperature leading to chilling lethality. Furthermore, these two mutants have an elevated resting [Ca2+]cyt, and a reduction of external Ca2+ lowers [Ca2+]cyt and represses its autoimmunity and cold susceptibility. The aca8 aca10 and the aca4 aca11 mutants are also susceptible to heat, likely resulting from more closed stomata and higher leaf surface temperature compared to the wild type. These observations support a model in which the regulation of resting [Ca2+]cyt is critical to how plants regulate biotic and abiotic responses. 

   more » « less
3. ZnT1 is a neuronal Zn2+/Ca2+ exchanger

   https://doi.org/10.1016/j.ceca.2021.102505  

   Gottesman, Noa; Asraf, Hila; Bogdanovic, Milos; Sekler, Israel; Tzounopoulos, Thanos; Aizenman, Elias; Hershfinkel, Michal (January 2022, Cell Calcium)
4. Using GCaMP3 to Study Ca2+ Signaling in Nicotiana Species

   https://doi.org/10.1093/pcp/pcx053  

   DeFalco, Thomas A.; Toyota, Masatsugu; Phan, Van; Karia, Purva; Moeder, Wolfgang; Gilroy, Simon; Yoshioka, Keiko (May 2017, Plant and Cell Physiology)
5. Coarse-Grained Modeling and Molecular Dynamics Simulations of Ca2+-Calmodulin

   https://doi.org/10.3389/fmolb.2021.661322  

   Nde, Jules; Zhang, Pengzhi; Ezerski, Jacob C.; Lu, Wei; Knapp, Kaitlin; Wolynes, Peter G.; Cheung, Margaret S. (August 2021, Frontiers in Molecular Biosciences)

   Calmodulin (CaM) is a calcium-binding protein that transduces signals to downstream proteins through target binding upon calcium binding in a time-dependent manner. Understanding the target binding process that tunes CaM’s affinity for the calcium ions (Ca 2+ ), or vice versa, may provide insight into how Ca 2+ -CaM selects its target binding proteins. However, modeling of Ca 2+ -CaM in molecular simulations is challenging because of the gross structural changes in its central linker regions while the two lobes are relatively rigid due to tight binding of the Ca 2+ to the calcium-binding loops where the loop forms a pentagonal bipyramidal coordination geometry with Ca 2+ . This feature that underlies the reciprocal relation between Ca 2+ binding and target binding of CaM, however, has yet to be considered in the structural modeling. Here, we presented a coarse-grained model based on the Associative memory, Water mediated, Structure, and Energy Model (AWSEM) protein force field, to investigate the salient features of CaM. Particularly, we optimized the force field of CaM and that of Ca 2+ ions by using its coordination chemistry in the calcium-binding loops to match with experimental observations. We presented a “community model” of CaM that is capable of sampling various conformations of CaM, incorporating various calcium-binding states, and carrying the memory of binding with various targets, which sets the foundation of the reciprocal relation of target binding and Ca 2+ binding in future studies. 

   more » « less