Publications of NIPGR Scientists

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Author: search.filters.author.Kaur, HarmeetSubject: search.filters.subject.abiotic stress

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    Arabidopsis Protein L-Isoaspartyl Methyltransferase repairs isoaspartyl damage to antioxidant enzymes and increases heat and oxidative stress tolerance
    (American Society for Biochemistry and Molecular Biology, 2020) Ghosh, Shraboni; Kamble, Nitin Uttam; Verma, Pooja; Salvi, Prafull; Petla, Bhanu Prakash; Roy, Shweta; Rao, Venkateswara; Hazra, Abhijit; Varshney, Vishal; Kaur, Harmeet; Majee, Manoj
    Stressful environments accelerate the formation of isoaspartyl (isoAsp) residues in proteins, which detrimentally affect protein structure and function. The enzyme Protein L-Isoaspartyl Methyltransferase (PIMT) repairs other proteins by reverting deleterious isoAsp residues to functional aspartyl residues. PIMT function previously has been elucidated in seeds, but its role in plant survival under stress conditions remains undefined. Herein, we used molecular, biochemical, and genetic approaches, including protein overexpression and knockdown experiments, in Arabidopsis to investigate the role of PIMTs in plant growth and survival during heat and oxidative stresses. We demonstrate that these stresses increase isoAsp accumulation in plant proteins, that PIMT activity is essential for restricting isoAsp accumulation, and that both PIMT1 and PIMT2 play an important role in this restriction and Arabidopsis growth and survival. Moreover, we show that PIMT improves stress tolerance by facilitating efficient reactive oxygen species (ROS) scavenging and thereby protecting the functionality of antioxidant enzymes from isoAsp-mediated damage during stress. Specifically, biochemical and MS/MS analyses revealed that antioxidant enzymes acquire deleterious isoAsp residues during stress, which adversely affect their catalytic activities, and that PIMT repairs the isoAsp residues and thereby restores antioxidant enzyme function. Collectively, our results suggest that the PIMT-mediated protein repair system is an integral part of the stress tolerance mechanism in plants, in which PIMTs protect antioxidant enzymes that maintain proper ROS homeostasis against isoAsp-mediated damage in stressful environments.
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    Arabidopsis SKP1-like protein 13 (ASK13) positively regulates seed germination and seedling growth under abiotic stresses
    (Oxford University Press, 2018) Rao, Venkateswara; Petla, Bhanu Prakash; Verma, Pooja; Salvi, Prafull; Kamble, Nitin Uttam; Ghosh, Sharboni; Kaur, Harmeet; Saxena, Saurabh C; Majee, Manoj
    SKP1 (S-Phase Kinase Associated Protein1) proteins are key members of the SCF (SKP-Cullin-F-box protein) E3 ligase complexes that ubiquitinate the target proteins and play diverse roles in plant biology. However, as compared to other members of the SCF complex, study of SKP1-like proteins is very limited in plants. In the present work, we report that Arabidopsis SKP1-like protein13 (ASK13) is differentially regulated in different organs, during seed development and germination, and is upregulated in response to abiotic stresses. Y2H library screening and subsequent in vivo interaction through BiFC analysis revealed that ASK13 not only interacts with F-box proteins but also with other proteins which are not components of SCF complexes. Biochemical analysis revealed that ASK13 not only exists as a monomer but also as a homo-oligomer or heteromer with other ASK proteins. Functional analysis using ASK13 overexpression and knockdown lines revealed that ASK13 positively influences seed germination and seedling growth particularly under abiotic stresses. Taken together, our data strongly suggests that apart from participation to form SCF complexes, ASK13 interacts with several other proteins and is implicated in different cellular processes distinct from protein degradation. Overall, ASK13 positively regulates seed germination and seedling growth particularly under abiotic stress conditions.