Dual and Dynamic Intracellular localisation of Arabidopsis thaliana SnRK1.1
J Exp Bot. 2019 Feb 7 [Epub ahead of print]
Blanco NE, Liebsch D, Guinea Díaz M, Strand Å, Whelan J

Abstract
Sucrose non-fermenting 1 (SNF1)-related protein kinase 1.1 (SnRK1.1, also known as KIN10 or SnRK1) has been identified as the catalytic subunit of the complex SnRK1, the Arabidopsis thaliana homologue of a central integrator of energy and stress signaling in eukaryotes dubbed as AMPK/Snf1/SnRK1. A nuclear localisation of SnRK1.1 has been previously described and is in line with its function as integrator of energy and stress signals. Here, using two biological models (Nicotianabenthamiana and Arabidopsisthaliana), native regulatory sequences, different microscopy techniques and manipulations of cellular energy status, it was found that SnRK1.1 is localised dynamically between the nucleus and endoplasmic reticulum (ER). This distribution was confirmed at a spatial and temporal level by co-localisation studies with two different fluorescent ER markers, one of them being the SnRK1.1-phosphorylation target HMGR. The ER and nuclear localisation displayed a dynamic behaviour in response to perturbations of the plastidic electron transport chain. These results suggest that an ER-associated SnRK1.1 fraction might be sensing the cellular energy status, being a point of crosstalk with other ER stress regulatory pathways.

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