B. Thines et al., "JAZ repressor proteins are targets of the SCFCOI1 complex during jasmonate signaling," Nature, 448: 661-8, 2007. (Cited in 81 papers)
John Browse of Washington State University and colleagues used transcript profiling and deletion constructs to identify the JAZ proteins, which repress jasmonates—plant hormones that orchestrate reproductive development and trigger defensive chemical responses to insects and bacteria in Arabidopsis. They also showed that, in order for developmental and defensive signaling to occur, an active form of jasmonate triggers another protein complex—SCFCOI1—to break down the JAZ proteins. With the suppressor proteins degraded, transcription of jasmonate-responsive genes can proceed.
"It made a lot of the genetics fall into place," says plant biologist Johnathan Napier of Rothamsted Research in Harpenden, UK. The parallels to auxin, another plant hormone, "give insight into conserved mechanisms that plants use for signaling and regulation of gene expression."
Another paper by Roberto Solano's team at the National Center for Biotechnology in Madrid, Spain, found that JAZ repressed a transcription factor that may also be a key player in activating the jasmonate signaling cascade. But, the teams still don't know which domains on JAZ proteins bind to SCFCOI1.
The next step:
Ning Zheng, a biochemist at the University of Washington, has almost finished crystallizing the jasmonate SCFCOI1-JAZ complex. "By solving the structure, we'll be able to tell right away which [domain] directly interacts with SCFCOI1," says Zheng.
|Increase in JAZ transcript induction for wild-type plants treated with jasmonate:|
|In stamens: 6-40 fold|
|In 7-day-old seedling: 8-60 fold|