| Literature DB >> 30713075 |
Yajun Pan1, Xuyang Chai1, Qifei Gao2, Liming Zhou2, Sisi Zhang1, Legong Li3, Sheng Luan4.
Abstract
Calcium is a universal signal in all eukaryotes, but the mechanism for encoding calcium signatures remains largely unknown. Calcium oscillations control pollen tube growth and fertilization in flowering plants, serving as a model for dissecting the molecular machines that mediate calcium fluctuations. We report that pollen-tube-specific cyclic nucleotide-gated channels (CNGC18, CNGC8, and CNGC7) together with calmodulin 2 (CaM2) constitute a molecular switch that either opens or closes the calcium channel depending on cellular calcium levels. Under low calcium, calcium-free calmodulin 2 (Apo-CaM2) interacts with CNGC18-CNGC8 complex, leading to activation of the influx channel and consequently increasing cytosolic calcium levels. Calcium-bound CaM2 dissociates from CNGC18/8 heterotetramer, closing the channel and initiating a downturn of cellular calcium levels. We further reconstituted the calcium oscillator in HEK293 cells, supporting the model that Ca2+-CaM-dependent regulation of CNGC channel activity provides an auto-regulatory feedback mechanism for calcium oscillations during pollen tube growth.Entities:
Keywords: calcium oscillations; cyclic nucleotide-gated channels; ion channel subunit composition; pollen tube growth
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Year: 2019 PMID： 30713075 DOI： 10.1016/j.devcel.2018.12.025
Source DB: PubMed Journal: Dev Cell ISSN： 1534-5807 Impact factor: 12.270