The 30th International Conference on Arabidopsis Research (ICAR 2019)

619 / 2019-04-24 10:29:52

The Arabidopsis RING-type E3 Ubiquitin Ligase AtAIRP5 Plays a Positive Role in ABA-mediated Drought Stress Response

ABA,E3 ligase,drought stress

Plenary track > Abiotic Stress

One of the crucial mechanisms to regulate protein turn-over is the ubiquitin-26S proteasome system (UPS). This system regulates diverse cellular processes, including cell cycle progression, hormone signaling, and defense against biotic and abiotic stresses. In the UPS, proteins that are designated for degradation by the 26S proteasome are usually covalently modified by the attachment of a polyubiquitin chain in a series of three enzymes, E1 ubiquitin (Ub) activating enzymes, E2 Ub conjugating enzymes, and E3 Ub ligases. E3 Ub ligases generally determine the specificity of target protein. The Arabidopsis ABA insensitive RING protein 5 (AtAIRP5) is a RING-type E3 ligase. The transcript level of AtAIRP5 was induced by ABA, NaCl, and drought. The transiently expressed AIRP5-GFP protein in Arabidopsis protoplasts localized to the cytosolic fraction with a punctate expression pattern. The airp5 knock-out mutant plants showed ABA insensitive phenotypes in terms of seed germination and stomatal closure. In contrast, germination and stomatal movement of AtAIRP5-overexpressing transgenic plants (35S:AtAIRP5-2xFlag) was sensitive relative to the wild-type plants in response to ABA. 35S:AtAIRP5-2xFlag plants also exhibited increased tolerance to drought stress. Together, these results suggest that AtAIRP5 is a positive regulator of an ABA-mediated drought stress response in Arabidopsis.