Phosphoproteomics of Arabidopsis Highly ABA-Induced1 identifies AT-Hook–Like10 phosphorylation required for stress growth regulation

Abstract

The clade A protein phosphatase 2C Highly ABA-Induced 1 (HAI1) plays an important role in stress signaling, yet little information is available on HAI1-regulated phosphoproteins. Quantitative phosphoproteomics identified phosphopeptides of increased abundance inhai1-2in unstressed plants and in plants exposed to low-water potential (drought) stress. The identity and localization of the phosphoproteins as well as enrichment of specific phosphorylation motifs indicated that these phosphorylation sites may be regulated directly by HAI1 or by HAI1-regulated kinases including mitogen-activated protein kinases, sucrose non-fermenting–related kinase 2, or casein kinases. One of the phosphosites putatively regulated by HAI1 was S313/S314 of AT-Hook–Like10 (AHL10), a DNA-binding protein of unclear function. HAI1 could directly dephosphorylate AHL10 in vitro, and the level ofHAI1expression affected the abundance of phosphorylated AHL10 in vivo. AHL10 S314 phosphorylation was critical for restriction of plant growth under low-water potential stress and for regulation of jasmonic acid and auxin-related gene expression as well as expression of developmental regulators includingShootmeristemless. These genes were also misregulated inhai1-2. AHL10 S314 phosphorylation was required for AHL10 complexes to form foci within the nucleoplasm, suggesting that S314 phosphorylation may control AHL10 association with the nuclear matrix or with other transcriptional regulators. These data identify a set of HAI1-affected phosphorylation sites, show that HAI1-regulated phosphorylation of AHL10 S314 controls AHL10 function and localization, and indicate that HAI1-AHL10 signaling coordinates growth with stress and defense responses.

At-Hook Motif Nuclear Localised Protein 18 as a Novel Modulator of Root System Architecture

“…The complexity of AHL action is further enhanced by feedback loop and phosphorylation controlled interactions with other modulators of gene expression. This was recently reported for AHL10 [15], a plant growth modulator under low-water potential stress,…”

“…The complexity of AHL action is further enhanced by feedback loop and phosphorylation controlled interactions with other modulators of gene expression. This was recently reported for AHL10 [15], a plant growth modulator under low-water potential stress, affecting jasmonic acid and auxin-synthesis and controlling developmental regulators such as SHOOT MERISTEMLESS (STM) [15].…”

“…There are 29 paralogues of the AHL proteins in Arabidopsis with conserved structure and predicted redundant behavior [13]. They are predicted to form homo and hetero oligomers (trimers) via the plants and prokaryotes conserved (PPC) domain [14,15,25,34]. The current knowledge indicates, that AHL genes are able to bridge regulation of several signal pathways acting as a nodes of the regulatory network integrating different inputs [15,35] The significance of overlapping expression domains, possible specific interactions among individual AHLs, and the resulting selectivity of particular oligomers for DNA binding, as well as interaction with other proteins via the PPC domain, could further extend and specify the mode of AHL action.…”

Genetic Dissection of Seed Dormancy using Chromosome Segment Substitution Lines in Rice (Oryza sativa L.)

“…A recent study showed that the DNA-binding protein AT-Hook-Like 10 (AHL10) could be dephosphorylated by a protein phosphatase Highly ABA-Induced1 (HAI1), which was involved in abiotic stress and abscisic acid signaling. AHL10 phosphorylation was crucial for hormone-related genes during drought stress [44]. Therefore, we thought our candidate gene LOC_Os03g01540 was somehow involved in the ABA signaling pathway to regulate seed dormancy.…”

H2S Regulation of Metabolism in Cucumber in Response to Salt-Stress Through Transcriptome and Proteome Analysis

“…Meng et al (2019) revealed jasmonate ZIM-domain protein 7 (JAZ7)-mediated drought tolerance in Arabidopsis using the tandem mass tags (TMT)-based quantitative proteomics and targeted metabolomics. The more advanced proteomics technology, such as quantitative phosphoproteomics are used to elucidate the mechanism that ABAinduced1 identifies AT-Hook-Like10 phosphorylation required for stress growth regulation in Arabidopsis (Wong et al, 2019). Combining comparative transcriptomic and proteomic analyses is also an effective way to investigate differential activation of response and metabolism pathways at the global level (Li et al, 2019).…”