Scholarlink

<p>The phytocystatins (PhyCYSs) of plants are members of the cystatin superfamily of proteins, which function as potent inhibitors of cysteine proteases. <i>Arabidopsis</i> PhyCYS2 (AtCYS2) is involved in various biological processes, including protein turnover, development and stress responses. However, the molecular mechanisms of <i>AtCYS2</i> expression under abiotic stresses remain obscure. Here, we demonstrate that <i>AtCYS2</i> transcript levels and <i>AtCYS2</i> promoter-driven β-glucuronidase (<i>P</i><sub><i>AtCYS2</i></sub>::<i>GUS</i>) activity are significantly induced by exogenous abscisic acid (ABA) as well as by drought, osmotic, and salt stress. Histochemical analysis of <i>P</i><sub><i>AtCYS2</i></sub>::<i>GUS</i> plants confirmed strong induction in leaves, particularly in guard cells, and in root tips following ABA and abiotic stress treatments. We further identified that the transcription factor ELONGATED HYPOCOTYL 5 (HY5) regulates <i>AtCYS2</i> expression by directly binding to its promoter. Transient overexpression of HY5 with the <i>P</i><sub><i>AtCYS2</i></sub>::<i>GUS</i> reporter in <i>Arabidopsis</i> protoplasts revealed that HY5 suppresses <i>AtCYS2</i> expression under ABA treatment. Consistent with its regulation through ABA signaling, <i>AtCYS2</i> expression was severely compromised in ABA-insensitive (<i>abi</i>) mutants but was markedly upregulated in the <i>hy5</i> null mutant. Collectively, these results indicate that while ABA signaling triggers <i>AtCYS2</i> induction, HY5 acts as a transcriptional repressor to fine-tune this response. This negative feedback loop likely prevents excessive protease inhibition, ensuring optimal adaptation to adverse environments.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

HY5 Negatively Regulates the Arabidopsis Phytocystatin AtCYS2 in Response to Abiotic Stresses

  • 期刊论文

  • 发表日期：

    2026年4月30日

查看全文
  • Jung Eun Hwang,
  • Jae Hyeok Lee,
  • Chang Ho Kang,
  • Chae Oh Lim

摘要

The phytocystatins (PhyCYSs) of plants are members of the cystatin superfamily of proteins, which function as potent inhibitors of cysteine proteases. Arabidopsis PhyCYS2 (AtCYS2) is involved in various biological processes, including protein turnover, development and stress responses. However, the molecular mechanisms of AtCYS2 expression under abiotic stresses remain obscure. Here, we demonstrate that AtCYS2 transcript levels and AtCYS2 promoter-driven β-glucuronidase (PAtCYS2::GUS) activity are significantly induced by exogenous abscisic acid (ABA) as well as by drought, osmotic, and salt stress. Histochemical analysis of PAtCYS2::GUS plants confirmed strong induction in leaves, particularly in guard cells, and in root tips following ABA and abiotic stress treatments. We further identified that the transcription factor ELONGATED HYPOCOTYL 5 (HY5) regulates AtCYS2 expression by directly binding to its promoter. Transient overexpression of HY5 with the PAtCYS2::GUS reporter in Arabidopsis protoplasts revealed that HY5 suppresses AtCYS2 expression under ABA treatment. Consistent with its regulation through ABA signaling, AtCYS2 expression was severely compromised in ABA-insensitive (abi) mutants but was markedly upregulated in the hy5 null mutant. Collectively, these results indicate that while ABA signaling triggers AtCYS2 induction, HY5 acts as a transcriptional repressor to fine-tune this response. This negative feedback loop likely prevents excessive protease inhibition, ensuring optimal adaptation to adverse environments.