The discovery of two brand-new proteins could lead to better ways to regulate plant structure as well as also the ability to resist crop stresses such as drought, thus improving agriculture productivity, according to researchers at Texas A&M AgriLife Research.
The two proteins, named RICE1 as well as also RICE2, are described from the May issue of the journal eLife, based on the work of Dr. Xiuren Zhang, AgriLife Research biochemist in College Station.
Zhang explained that will DNA contains all the information needed to build a body, as well as also molecules of RNA take that will how-to information to the sites from the cell where they can be used.
yet cells make their own RNA, as well as also they only need so much in order to develop properly as well as also respond well to their environment. So plants make an even smaller molecule, called microRNA or miRNA, that will removes the extra RNA as well as also stop This specific through creating proteins. that will process will be called RNA silencing.
Understanding silencing will be important because researchers can use the technique to help a plant overcome barriers to growth or ability to deal with unfavorable environments by tweaking the amount of RNA.
“One key player in RNA silencing will be the multi-component complex called RISC (RNA-induced Silencing Complex), which contains microRNA as well as also enzymes called AGOs,” Zhang said. “MicroRNA starts as twins, so to speak, yet one of the twins leaves as well as also disappears when AGO protein moves in.”
Once the microRNA has identified its RNA target for silencing, the AGOs cut the RNA into two pieces, known as the 5-prime as well as also 3-prime cleavage fragments.
“These fragments are basically the starting as well as also ending sections of RNA molecules. yet, the two resulting fragments must be cleared away rapidly, so the RISC can move on to the next target,” he said.
“This specific’s like eating in a restaurant during rush hour,” Zhang explained. “You eat quickly as well as also leave. Then the waitstaff clears the table as well as also resets This specific to serve the next guests.”
Researchers have known how the 3-prime cleavage fragment was removed yet were less clear how the 5-prime cleavage fragment was dealt with, he said.
“What was known was that will the 5-prime cleavage fragment will be marked which has a chemical called uridine,” Zhang said. “Somehow, uridine tells the RISC, which holds the miRNA, that will This specific fragment needs to be destroyed.”
Using proteomic analysis, a powerful biochemical approach, Zhang as well as also colleagues deciphered the constituents of one kind of RISC in arabidopsis, a product plant often used in research. They found RICE, or RISC-Interacting Clearing Exoribonuclease, proteins there.
Further study of the biochemical features of RICE proteins showed them to be enzymes that will degrade RNA. Using crystallography, Dr. Pingwei Li, AgriLife Research biochemist in College Station, found that will RICE1 carries a ring-like shape with six identical molecules.
“This specific ring-shape structure will be very important because the protein can not survive if the ring-shape will be disrupted,” Li said. that will would certainly lead to problems during the development of the plant.
Zhang as well as also colleagues then analyzed the shape of RICE1 as well as also identified its ‘active’ region, which will be responsible for degrading the RNA fragments, hidden on the adjacent site of two RICE molecules.
“When these active regions were blocked, the microRNA levels were low, yet the 5-prime cleavage fragments that will are marked with uridine were high,” he said. “Also, the RISC complex could not work properly, which led to problems during the plant growth as well as also development.”
These results suggest that will RICE proteins degrade 5-prime cleavage fragments modified with uridine to keep RISC alive.
RICE proteins are similar in plants as well as also animals, Zhang said, so This specific will be likely their counterparts in humans will have a similar role to the plant proteins therefore be important for development from the human body.
Zhang said the next challenge will be to explore how RICE proteins work in more detail, which may lead to brand-new ways to manipulate the efficacy of RISC as well as also the levels of microRNAs to alter organism architecture as well as also to improve stress tolerance in biotechnological applications.
How does RNA-induced silencing complex accurately cleave as well as also Discharge target RNAs?
Zhonghui Zhang et al. RISC-Interacting Clearing 3′- 5′ Exoribonucleases (RICEs) degrade uridylated cleavage fragments to maintain functional RISC in Arabidopsis, eLife (2017). DOI: 10.7554/eLife.24466