JUL1, Ring-Type E3 Ubiquitin Ligase, Is Involved in Transcriptional Reprogramming for ERF15-Mediated Gene Regulation

Abstract

JAV1-associated ubiquitin ligase 1 (JUL1) is a RING-type E3 ubiquitin ligase that catalyzes ubiquitination of JAV1, a jasmonate signaling repressor, in Arabidopsis thaliana in response to herbivore attack. Here we present a new insight into the nature of JUL1 as a multi-targeting enzyme for not only JAV1 but also transcription factors (TFs) screened using in vitro and in vivo protein interaction assays. Reporter assays using protoplasts showed that the JUL1-interacting TFs (JiTFs), including ERF15, bZIP53 and ORA59, were involved in transcriptional activation of jasmonate-responsive PDF1.2 and abscisic acid-responsive GEA6. Likewise, assays using mutant plants suggested that the 3 JiTFs were indeed responsible for transcriptional regulation of PDF1.2 and/or GEA6, and ERF15 and ORA59 were substantially responsible for the anti-herbivore trait. In vitro protein ubiqutination assays showed that JUL1 catalyzed ubiqutination of JAV1 but not any of the TFs. This was in accord with the finding that JUL1 abolished JAV1′s interference with ERF15 function, according to the reporter assay. Moreover, of great interest is our finding that ERF15 but not bZIP53 or ORA59 serves as a scaffold for the JAV1/JUL1 system, indicating that there is narrow selectivity of the transcriptional reprogramming by the JAV1/JUL1 system.

Recent Advances in Plant–Insect Interactions

“…Gen-ichiro Arimura and co-workers focus on the nature of the transcriptional regulation of the jasmonic acid (JA)-responsive plant defensin gene PDF1.2 and abscisic acid (ABA)-responsive UDP-D-glucuronate 4-epimerase 6 (GEA6) in Arabidopsis thaliana [1]. This paper introduces transcriptional reprogramming in the defense response against herbivores in higher plants, which is further and deeply elaborated by the review paper of Biao Jin and co-workers [2].…”