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Start date: 2025Subject: search.filters.subject.feedback regulation

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    Delineating microRNA169-Nuclear Factor Y-Subunit a module for its potential implications in crop improvement
    (John Wiley & Sons, 2026) Chakraborty, Anirban; Sharma, Shambhavi; Pandey, Girdhar K.; Bhatia, Sabhyata; Prasad, Manoj
    Climate change considerably impacts plant growth and productivity by inducing stress responses. This, along with the problems of feeding the ever-increasing global population, could be mitigated by generating climate-resilient crop varieties with enhanced productivity. However, an exhaustive account of the key regulatory processes that underlie developmental and stress-responsive pathways is a prerequisite for generating improved crop varieties. Towards this, our study, for the first time, provides an exhaustive compilation of the potential regulatory pathways impacted by the miR169-NFYA network in plants. The NFYA transcription factors belong to a class of nuclear factor-encoding genes directly influencing the transcription of many genes involved in developmental and stress responses. Meanwhile, miR169 provides a layer to NFYA-mediated gene regulation by post-transcriptionally suppressing the expression of these transcription factors. Evidence from several studies shed light on key molecular signatures related to hormone synthesis and signaling, calcium signaling, epigenetic regulation, nutrient starvation and miRNA biogenesis that could serve as downstream components of the miR169-NFYA cascade in plants. This ability of miR169-NFYA nexus to impact a wide range of biological processes makes it a suitable toolbox for developing tailor-made crop varieties through appropriate genetic manipulation strategies.
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    Isopropylmalate synthase regulatory domain removal abolishes feedback regulation at the expense of leucine homeostasis in plants
    (Oxford University Press, 2025) Varghese, Mohan; Kumar, Roshan; Sharma, Aprajita; Lone, Asif; Gershenzon, Jonathan; Bisht, Naveen C.
    In the leucine (Leu) biosynthesis pathway, homeostasis is achieved through a feedback regulatory mechanism facilitated by the binding of the end-product Leu at the C-terminal regulatory domain of the first committed enzyme, isopropylmalate synthase (IPMS). In vitro studies have shown that removing the regulatory domain abolishes the feedback regulation on plant IPMS while retaining its catalytic activity. However, the physiological consequences and underlying molecular regulation on Leu flux upon removing the IPMS C-terminal domain remain to be explored in plants. Here, we removed the IPMS C-terminal regulatory domain using a CRISPR/Cas9-based gene editing system and studied the resulting impact on the Leu biosynthesis pathway under in planta conditions. Absence of the IPMS regulatory domain unexpectedly reduced the formation of the end product Leu but increased the levels of Leu pathway intermediates in mustard (Brassica juncea). Additionally, delayed growth was observed when IPMS devoid of the regulatory domain was introduced into IPMS-null mutants of Escherichia coli and Arabidopsis thaliana. Further, a detailed biochemical analysis showed that in the absence of the C-terminal regulatory domain, a Leu pathway intermediate (α-ketoisocaproate) could compete with the native IPMS substrate (2-oxoisovalerate) for the active site. Combining these metabolomic, biochemical, and in planta analyses, we demonstrate that the C-terminal regulatory domain of IPMS is critical for maintaining Leu-Val homeostasis in plants.