PLANT U-BOX PROTEIN10 Regulates MYC2 Stability in Arabidopsis

Abstract

MYC2 is an important regulator for jasmonic acid (JA) signaling, but little is known about its posttranslational regulation. Here, we show that the MYC2 C-terminal region interacted with the PLANT U-BOX PROTEIN10 (PUB10) armadillo repeats in vitro. MYC2 was efficiently polyubiquitinated by PUB10 with UBC8 as an E2 enzyme and the conserved C249 in PUB10 was required for activity. The inactive PUB10(C249A) mutant protein retained its ability to heterodimerize with PUB10, thus blocking PUB10 E3 activity as a dominant-negative mutant. Both MYC2 and PUB10 were nucleus localized and coimmunoprecipitation experiments confirmed their interaction in vivo. Although unstable in the wild type, MYC2 stability was enhanced in pub10, suggesting destabilization by PUB10. Moreover, MYC2 half-life was shortened or prolonged by induced expression of PUB10 or the dominant-negative PUB10(C249A) mutant, respectively. Root growth of pub10 seedlings phenocopied 35S:MYC2 seedlings and was hypersensitive to methyl jasmonate, whereas 35S:PUB10 and jin1-9 (myc2) seedlings were hyposensitive. In addition, the root phenotype conferred by MYC2 overexpression in double transgenic plants was reversed or enhanced by induced expression of PUB10 or PUB10(C249A), respectively. Similar results were obtained with three other JA-regulated genes, TAT, JR2, and PDF1.2. Collectively, our results show that MYC2 is targeted by PUB10 for degradation during JA responses.

Arabidopsis MYC Transcription Factors Are the Target of Hormonal Salicylic Acid/Jasmonic Acid Cross Talk in Response to Pieris brassicae Egg Extract

“…In all these cases, MYC protein degradation was mediated by the proteasome. Recently, it was shown that MYC2 is polyubiquitinated by PLANT U-BOX PROTEIN10 (PUB10), which belongs to the U-box family of E3 ligases (Jung et al, 2015). There thus is growing evidence that the JA pathway is tightly coordinated with other environmental inputs and that part of this regulation operates at the translational level.…”

Identification of loci and candidate genes for plant height in soybean (Glycine max) via genome‐wide association study

“…In the present study, a total of 134 potential candidate genes were identified in 200‐kb genomic regions among the 14 association signals. Some genes associated with cell division or elongation, plant hormone metabolisms, proteins modification or degradation and signalling or transport of specific proteins, have been found to participate in the regulation of PH in soybean (Jung et al, ; Ubeda‐Tomas & Bennett, ; Wang, Zhao, et al, ; Yao et al, ; Zhong et al, ). To further identify the candidate genes that regulated PH, haplotype analysis of candidate genes was conducted.…”

Conventional and unconventional ubiquitination in plant immunity

“…The basic helix–loop–helix (bHLH) transcription factor MYC2 has emerged in recent years as a master regulator of many aspects of the JA signalling pathway and as a key point of cross‐talk between the signalling pathways of JA and other phytohormones, such as ABA, SA, gibberellins (Gas) and auxin (IAA) (Kazan and Manners, ). A recent report has shown that MYC2 is targeted by the U‐box‐type E3 ubiquitin ligase PUB10 for ubiquitination and subsequent degradation during the JA response (Jung et al ., ), suggesting that PUB10 negatively regulates the JA signalling pathway. However, the plant immunity‐related phenotype on the PUB10 loss‐of‐function and PUB10‐overexpressing plants was not characterized in the report.…”