Phosphorylation of Arabidopsis SINA2 by CDKG1 affects its ubiquitin ligase activity

Abstract

BackgroundSEVEN IN ABSENTIA (SINA) is a RING domain-containing ubiquitin ligase involved in Drosophila eye formation. SINA-like proteins in plants are involved in several signaling pathways. Of the 18 SINA-like proteins identified in Arabidopsis, SEVEN IN ABSENTIA 2 (SINA2) lacks a canonical RING domain and is thought to lack ubiquitin ligase activity.ResultsOur results show that SINA2 has E3 ligase activity in vitro, raising the possibility that a modified B-box domain may compensate for its lack of a RING domain. SINA2 physically interacts with the nuclear protein CYCLIN-DEPENDENT KINASE G1 (CDKG1), which acts as a positive regulator of plant responses to abiotic stress. CDKG1 is expressed in multiple tissues and its expression increased in response to abscisic acid (ABA) and osmotic stress. Transgenic Arabidopsis plants that ectopically express CDKG1 exhibit increased tolerance to ABA and osmotic stress treatments during seed germination and cotyledon development, while the loss-of-function cdkg1 mutant plants show reduced tolerance to ABA and osmotic stress treatments. Moreover, CDKG1-dependent phosphorylation of SINA2 positively affects its E3 ubiquitin ligase activity.ConclusionsBased on these results, we propose that CDKG1 modulates SINA2 ubiquitin ligase activity to regulate its effect on plant responses to ABA and osmotic stress.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1364-8) contains supplementary material, which is available to authorized users.

OsDIRP1, a Putative RING E3 Ligase, Plays an Opposite Role in Drought and Cold Stress Responses as a Negative and Positive Factor, Respectively, in Rice (Oryza sativa L.)

“…In fact, OsDIRP1 is predicted to possess at least six putative phosphorylation sites (Supplementary Figure S6). Phosphorylation was shown to be required to activate Arabidopsis ICE1 (Inducer of CBF Expression), SINA2 (SEVER IN ABSENTIA), and RFP34/CHYR1 (RING ZINC-FINGER PROTEIN34/CHY ZINC-FINGER AND RING PROTEIN 1) E3 ligases as well as the rice OsPUB15 E3 Ub ligase (Ding Y. et al, 2015; Ding S. et al, 2015; Wang et al, 2015; Chen et al, 2018). Second, OsDIRP1 may not be a bona fide E3 ligase, but instead may play an unidentified role in response to environmental stimuli.…”

A Functional Kinase Is Necessary for Cyclin-Dependent Kinase G1 (CDKG1) to Maintain Fertility at High Ambient Temperature in Arabidopsis

“…The suggestion that the CDKG1 gene has arisen from a retrotransposition event from the CDKG2 gene in the Arabidopsis lineage after the split from other Brassicaceae ( Zhang et al, 2005 ; Beilstein et al, 2010 ) has raised questions related to their function and why both genes have been retained. Even though CDKG1 and CDKG2 proteins share 64% amino acid similarity, we and others have shown that the two kinases perform different functions ( Huang et al, 2013 ; Zheng et al, 2014 ; Ma et al, 2015 ; Cavallari et al, 2018 ; Chen et al, 2018 ; Nibau et al, 2020a , b ). On the other hand, we were not able to recover double cdkg1-1cdkg2-1 mutants despite both single mutants showing only mild growth phenotypes.…”

Genetic control of flowering in greater yam (Dioscorea alata L.)

“…In A. thaliana , it is highly and mostly expressed during pollen development (The Arabidopsis Information Resource [ 27 ];). Its activity is modulated by CDKG1 [ 28 ], which is involved in thermal-sensitive male meiosis [ 29 ].…”