Abcisic acid (ABA) has an awful lot on its plate. This plant hormone handles a staggeringly diverse array of jobs, from controlling seed germination to combating pathogen infection to dealing with drought conditions and scientists have assumed that the mechanisms regulating its activity must be equally elaborate.
“ABA signal transduction pathways were thought to be a web-like, complex network in which many components have ‘some role’,” says Kazuo Shinozaki of the RIKEN Plant Science Center in Yokohama.
Taishi Umezawa of Shinozaki's team recently revealed the involvement of a subset of SNF1-related protein kinase 2 (SnRK2) proteins, which get activated via addition of phosphate groups in the aftermath of ABA signaling, enabling them to turn on downstream transcriptional activators. However, these signals also need to be turned off, and Takashi Hirayama’s team at the RIKEN Advanced Science Institute in Wako identified several protein phosphatase 2C (PP2C) enzymes that may constrain ABA signaling.
By combining their expertise, these two teams have now successfully sketched out the surprisingly simple processes underlying ABA regulation1. Thale cress plants lacking the three members (kinases) of SnRK2 subclass III are minimally responsive even to high ABA levels, highlighting their central role in this pathway. Subsequent experiments revealed that these kinases physically interact with a subset of PP2C enzymes, which directly remove the phosphate group; mutations that inactivate these PP2Cs lead in turn to SnRK2 hyperactivation.
Under normal conditions, PP2C appears to keep SnRK2 in a constant state of inactivation—but when ABA binds its receptor, the resulting complex interacts with PP2C in a manner that lifts this inhibition. Accordingly, the researchers found that mutant forms of PP2C that lack an ABA receptor-binding domain establish resistance to ABA signaling.
The investigators were taken aback by the simplicity of the model they identified. “We think this is the major ABA signaling pathway—and may even be the only ABA signaling pathway—[and it] consists of only four components: soluble ABA receptors, PP2C, SnRK2, and [downstream] transcription factors or other enzymes,” says Shinozaki. “That is very simple compared with our previous understanding.”
Of course, some additional levels of complexity still remain to be uncovered—most notably, understanding ABA’s part in the greater ecosystem of plant hormonal regulation. “We are interested in the molecular basis of cross-talk among plant hormone responses,” says Shinozaki. “Now that one major ABA signaling pathway is established, we can investigate this cross-talk at the molecular level.”
The corresponding author for this highlight is based at the Molecular Membrane Biology Laboratory, RIKEN Advanced Science Institute
Saeko Okada | Research asia research news
New catalyst controls activation of a carbon-hydrogen bond
21.11.2017 | Emory Health Sciences
The main switch
21.11.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
21.11.2017 | Physics and Astronomy
21.11.2017 | Physics and Astronomy
21.11.2017 | Life Sciences