An abscisic acid-responsive protein interaction network for sucrose non-fermenting related kinase1 in abiotic stress response

Abstract

Yeast Snf1 (Sucrose non-fermenting1), mammalian AMPK (5′ AMP-activated protein kinase) and plant SnRK1 (Snf1-Related Kinase1) are conserved heterotrimeric kinase complexes that re-establish energy homeostasis following stress. The hormone abscisic acid (ABA) plays a crucial role in plant stress response. Activation of SnRK1 or ABA signaling results in overlapping transcriptional changes, suggesting these stress pathways share common targets. To investigate how SnRK1 and ABA interact during stress response in Arabidopsis thaliana, we screened the SnRK1 complex by yeast two-hybrid against a library of proteins encoded by 258 ABA-regulated genes. Here, we identify 125 SnRK1-interacting proteins (SnIPs). Network analysis indicates that a subset of SnIPs form signaling modules in response to abiotic stress. Functional studies show the involvement of SnRK1 and select SnIPs in abiotic stress responses. This targeted study uncovers the largest set of SnRK1 interactors, which can be used to further characterize SnRK1 role in plant survival under stress.

SnRK1α1 Antagonizes Cell Death Induced by Transient Overexpression of Arabidopsis thaliana ABI5 Binding Protein 2 (AFP2)

“…We have previously shown that AFP2 interacts with the SnRK1 catalytic subunits, SnRKα1 and SnRKα2, in Y2H and BiFC assays ( Carianopol et al, 2020 ). While transiently expressing AFP2 with the empty vector control in N. benthamiana , we observed that AFP2 induced CD in the infiltrated area of the leaf ( Figures 1A, B ; Supplemental Figure 1 ).…”

“…AFP2 EAR did not activate the LacZ reporter and results with the leucine reporter were inconclusive, since there was similar yeast growth also with the negative control (empty vector) ( Figure 4A ). SnRK1α1 and α2 autoactivated when fused to the DBD ( Carianopol et al, 2020 ), therefore, reciprocal interactions could not be tested.…”

“…AFPs play important roles in plant development, ABA and stress responses in plants, and do so by repressing transcription through recruitment of HDACs at target loci as well as other yet unknown mechanisms ( Tang et al, 2016 ; Lynch et al, 2017 ; Chang et al, 2018 ; Chang et al, 2019 ). Recently, we showed that AFP2 interacts with the α1 and α2 kinase subunits of SnRK1 ( Carianopol et al, 2020 ), a well conserved ser/thr kinase complex that is activated in response to stress to restore cellular energy homeostasis. However, the function of this interaction was unknown.…”

“…Our results show that SnRK1α1, but not SnRK1α2, rescues AFP2-induced CD, suggesting a specific role for SnRK1α1 in CD. The SnRK1α1 and SnRK1α2 kinases have been previously shown to play different roles in flowering time, as well as specific roles during osmotic and salt stress responses ( Williams et al, 2014 ; Carianopol et al, 2020 ). High-throughput yeast two-hybrid screens identified different partners for SnRK1α1 and SnRK1α2, suggesting that SnRK1 kinases are likely to regulate plant growth and stress responses by interacting with different target proteins ( Carianopol et al, 2020 ).…”

“…To identify common targets of the ABA and SnRK1 signaling pathways, we conducted a high-troughput yeast two-hybrid (Y2H) screen and showed that the SnRK1 complex interacts with 125 ABA-regulated proteins, including both positive and negative regulators of ABA signaling, suggesting that the SnRK1 and ABA signaling pathways largely intersect during plant stress responses ( Carianopol et al, 2020 ). One of the interactors identified is ABI Five Binding Protein2 (AFP2), which belongs to a subfamily of four negative regulators of ABI5/ABFs; these AFPs are members of the Novel Interactor of JAZ (NINJA) and NINJA-like superfamily of adaptor proteins ( Lopez-Molina et al, 2003 ; Garcia et al, 2008 ; Lynch et al, 2017 ).…”