ESCRT-I Component VPS23A Affects ABA Signaling by Recognizing ABA Receptors for Endosomal Degradation

Area of Science:

• Plant Science
• Molecular Biology
• Biochemistry

Background:

• The discovery of PYR/PYL/RCAR receptors significantly advanced plant science.
• The role of endosomal sorting in regulating plant hormone signaling, particularly abscisic acid (ABA), remains largely unexplored.

Purpose of the Study:

• To investigate the role of VPS23A, a component of ESCRT-I, in ABA signaling.
• To elucidate the relationship between VPS23A and PYR/PYL/RCAR-type ABA receptors.

Main Methods:

• Investigated the epistatic relationship between VPS23A and ABA receptors.
• Analyzed the effect of VPS23A disruption on OST1 kinase activity under ABA treatment.
• Performed co-immunoprecipitation assays to detect interactions between VPS23A, PYR1/PYLs, and ubiquitin.
• Assessed the ubiquitination status of PYL4 in vivo.
• Examined the impact of VPS23A on the subcellular localization of PYR1 and the stability of PYL4.

Main Results:

• VPS23A negatively regulates ABA signaling and has an epistatic relationship with PYR/PYL/RCAR receptors.
• Disruption of VPS23A enhances OST1 kinase activity in response to ABA.
• VPS23A interacts with PYR1/PYLs and K63-linked diubiquitin, and PYL4 undergoes K63-linked ubiquitination.
• VPS23A influences the subcellular localization of PYR1 and the stability of PYL4, suggesting vacuole-mediated degradation.

Conclusions:

• VPS23A negatively regulates ABA signaling by targeting PYR1/PYLs for vacuole-mediated degradation.
• This study provides novel insights into the turnover mechanisms of ABA receptors and the function of ESCRT machinery in plant hormone signaling.