Browsing by Author "Shukla, Brihaspati N."

Now showing 1 - 3 of 3

The FCS-LIKE ZINC FINGER 6 and 10 are involved in regulating osmotic stress responses in Arabidopsis
(Taylor & Francis Group, 2019) Jamsheer, K Muhammed; Singh, Dhriti; Sharma, Mohan; Sharma, Manvi; Jindal, Sunita; Mannully, Chanchal T.; Shukla, Brihaspati N.; Laxmi, Ashverya
The TARGET OF RAPAMYCIN-SNF1-RELATED PROTEIN KINASE 1 (TOR-SnRK1) arms race is a key regulator of plant growth in response to energy fluctuations and stress. Recently, we have identified that two members of the FCS-LIKE ZINC FINGER (FLZ) protein family, FLZ6 and 10, repress SnRK1 signaling and thereby involved in the activation of the TARGET OF RAPAMYCIN (TOR) signaling. In this study, we demonstrate that FLZ6 and 10 are also involved in the regulation of osmotic stress responses. Downregulation of FLZ6 and 10 results in enhanced expression of stress-responsive genes and better resilience towards osmotic stress at the seedling stage. These results indicate that FLZ6 and 10 are involved in the regulation of stress mitigation in plants through directly affecting SnRK1 signaling.
The FCS-like zinc finger scaffold of the kinase SnRK1 is formed by the coordinated actions of the FLZ domain and intrinsically disordered regions
(The American Society for Biochemistry and Molecular Biology, 2018) Jamsheer, K Muhammed; Shukla, Brihaspati N.; Jindal, Sunita; Gopan, Nandu; Mannully, Chanchal Thomas; Laxmi, Ashverya
The SNF1-related protein kinase 1 (SnRK1) is a heterotrimeric eukaryotic kinase that interacts with diverse proteins and regulates their activity in response to starvation and stress signals. Recently, the FCS-like zinc finger (FLZ) proteins were identified as a potential scaffold for SnRK1 in plants. However, the evolutionary and mechanistic aspect of this complex formation is currently unknown. Here, in silico analyses predicted that FLZ proteins possess conserved intrinsically disordered regions (IDRs) with a propensity for protein binding in the N and C termini across the plant lineage. We observed that the Arabidopsis FLZ proteins promiscuously interact with SnRK1 subunits, which formed different isoenzyme complexes. The FLZ domain was essential for mediating the interaction with SnRK1α subunits, whereas the IDRs in the N termini facilitated interactions with the β and βγ subunits of SnRK1. Furthermore, the IDRs in the N termini were important for mediating dimerization of different FLZ proteins. Of note, the interaction of FLZ with SnRK1 was confined to cytoplasmic foci, which colocalized with the endoplasmic reticulum. An evolutionary analysis revealed that in general, the IDR-rich regions are under more relaxed selection than the FLZ domain. In summary, the findings in our study reveal the structural details, origin, and evolution of a land plant–specific scaffold of SnRK1 formed by the coordinated actions of IDRs and structured regions in the FLZ proteins. We propose that the FLZ protein complex might be involved in providing flexibility, thus enhancing the binding repertoire of the SnRK1 hub in land plants.
Glucose-regulated HLP1 acts as a key molecule in governing thermomemory
(American Society of Plant Biologists, 2019) Sharma, Mohan; Banday, Zeeshan Zahoor; Shukla, Brihaspati N.; Laxmi, Ashverya
Induction of heat shock proteins (HSPs) in response to heat stress (HS) is indispensable for conferring thermotolerance. Glucose, a fundamental signaling and metabolic molecule, provides energy to stressed seedlings to combat stress. The recovery of stressed plants from detrimental HS in response to glucose is largely mediated by HSPs, but the mechanistic basis of this thermotolerance is not well defined. In this study, we show that glucose has a prominent role in providing thermotolerance. Glucose-mediated thermotolerance involves HSP induction via the TOR-E2Fa signaling module. Apart from HSPs, TOR-E2Fa also regulates the Arabidopsis (Arabidopsis thaliana) ortholog of human Hikeshi, named HIKESHI-LIKE PROTEIN1 (HLP1). Expression of proHLP1::GUS in the shoot apical meristem (SAM) after heat stress coincides with TOR-E2Fa expression, substantiating a role for TOR-E2Fa-HLP1 in providing thermotolerance. We also demonstrate that glucose along with heat could induce proliferation activity in the SAM after HS recovery, which was arrested by the TOR inhibitor AZD-8055. Molecular and physiological studies suggest that HS-activated HSFA1s also positively regulate HLP1 transcription, suggesting convergence of the glucose and HS signaling pathways. Loss of functional HLP1 causes HS hypersensitivity, while HLP1 overexpressors (OEs) display increased thermotolerance. HLP1 binds to the promoters of glucose-regulated HS responsive genes and promotes chromatin acetylation. In addition, glucose modifies the chromatin landscape at thermomemory-related loci by promoting H3K4 trimethylation (H3K4me3). Glucose-primed accumulation of H3K4me3 at thermomemory-associated loci is mediated through HLP1. These findings reveal the novel function of glucose-regulated HLP1 in mediating thermotolerance/thermomemory response.