Oligouridylate Binding Protein 1b Plays an Integral Role in Plant Heat Stress Tolerance

Abstract

Stress granules (SGs), which are formed in the plant cytoplasm under stress conditions, are transient dynamic sites (particles) for mRNA storage. SGs are actively involved in protecting mRNAs from degradation. Oligouridylate binding protein 1b (UBP1b) is a component of SGs. The formation of microscopically visible cytoplasmic foci, referred to as UBP1b SG, was induced by heat treatment in UBP1b-overexpressing Arabidopsis plants (UBP1b-ox). A detailed understanding of the function of UBP1b, however, is still not clear. UBP1b-ox plants displayed increased heat tolerance, relative to control plants, while ubp1b mutants were more sensitive to heat stress than control plants. Microarray analysis identified 117 genes whose expression was heat-inducible and higher in the UBP1b-ox plants. RNA decay analysis was performed using cordycepin, a transcriptional inhibitor. In order to determine if those genes serve as targets of UBP1b, the rate of RNA degradation of a DnaJ heat shock protein and a stress-associated protein (AtSAP3) in UBP1b-ox plants was slower than in control plants; indicating that the mRNAs of these genes were protected within the UBP1b SG granule. Collectively, these data demonstrate that UBP1b plays an integral role in heat stress tolerance in plants.

Vascular plant one-zinc-finger protein 2 is localized both to the nucleus and stress granules under heat stress in Arabidopsis

“…UBP1 acts as SGs' central component, and protects heat stress tolerance-related transcripts from exonucleolytic degradation via interactions with the 3 0 -UTR of mRNAs to play a fundamental role in thermotolerance. 13,21,22 In plants, another DNA-and RNA-biding family of proteins, the CCCH-type tandem zinc finger proteins (TZFs), colocalized with both SGs and P-bodies under various stressful conditions including heat and hypoxia. TZFs are highly conserved among eukaryotes and perform critical functions in mRNA metabolism in animals and yeast.…”

Polysomes, Stress Granules, and Processing Bodies: A Dynamic Triumvirate Controlling Cytoplasmic mRNA Fate and Function

“…UBP1A and UBP1C reversibly aggregate Gloggnitzer et al (2014) into cytoplasmic poly(A) mRNA granules upon hypoxic and heat stress (Sorenson and Bailey-Serres, 2014). Similarly, UBP1B reversibly forms SGs under heat stress and plays a crucial role in ABA signaling and heat stress tolerance (Nguyen et al, 2016(Nguyen et al, , 2017). An analysis of RNA decay kinetics suggested that UBP1B complexes (UBP1B-SGs) protect stress-related mRNAs from degradation during heat stress (Nguyen et al, 2016).…”

“…Similarly, UBP1B reversibly forms SGs under heat stress and plays a crucial role in ABA signaling and heat stress tolerance (Nguyen et al, 2016(Nguyen et al, , 2017). An analysis of RNA decay kinetics suggested that UBP1B complexes (UBP1B-SGs) protect stress-related mRNAs from degradation during heat stress (Nguyen et al, 2016). Likewise, UBP1C is required for plant survival of low-oxygen stress.…”

Overexpression of oligouridylate binding protein 1b results in ABA hypersensitivity

“…Several potential targets of UBP1b, including mRNAs of a DNAJ binding protein and a zinc finger binding protein, were identified. 5 Our microarray analysis of UBP1b-ox plants subjected to non-stressed or heat stress conditions revealed higher expression of several ABA signaling-related genes, suggesting that the UBP1b functions in the ABA signaling pathway. Root elongation and seed germination assays demonstrated that UBP1b-ox plants exhibit an ABA-hypersensitive phenotype.…”

“…Understanding the molecular mechanisms responsible for environmental stress tolerance in plants is essential for developing strategies to improve plant productivity under unfavorable environmental conditions. Recent studies have revealed that post-transcriptional regulatory mechanisms, such as the addition of 5 0 cap structure, 1 splicing, 2 3 0 poly A addition, 3 and control of mRNA degradation 4 and storage, 5 are involved in stress response and adaptation.…”