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inside the ring, with the help of an “island” domain, so named because it appears to float in the center of the receptor’s circular interior. AGRICULTURE: First look at sensor The two research for plant hormone holds surprises teams—one led by structural biologist Jijie Chai at Tsinghua UniHE FIRST X-RAY crystal structures of a key versity, in Beijing, and the plant hormone receptor protein have been other by Joanne Chory, a plant solved by two independent research teams biologist at the Salk Institute, working in the U.S. and China (Nature, DOI: 10.1038/ in La Jolla, Calif.—knew of each othnature10178 and 10.1038/nature10153). The receptor er’s work, but did not share data prior to submitsenses brassinolide, a steroid that helps bulk up foliage, ting the papers for publication. When Chai finally read fight pathogens, and mediate fertilization. It is among Chory’s paper, “I could not find a difference between the last of the major plant hormone receptors to have their structure and ours,” he says. The impressive simiits structure solved. larity “certainly helped” convince The discovery sets the stage for reviewers who were expecting BRI1 OH plant researchers to improve the to look like its mammalian analog, yields of lettuce and cotton, two the horseshoe-shaped steroid reH crops that depend on brassinoceptor called TLR3, Chory says. OH lide signaling for large harvests. The researchers were also surH The structure will also help plant prised to find that BRI1 does not HO scientists understand and bolster seem to dimerize as TLR3 does, H H agricultural crops’ immunity to Chai says. O microbial pathogens. Chemists could use BRI1’s HO H Surprisingly, the brassinolide structure to develop small, O receptor “looks totally different receptor-activating molecules that Brassinolide than what was expected,” says aren’t as complicated—and therePing He, a plant biochemist at fore not as expensive to produce or Texas A&M University. People so strongly believed the purify—as brassinolide. The structure might also help receptor would adopt a horseshoe shape, He explains, plant scientists engineer the receptor to increase crop that the wrong structure was widely “put in textbooks.” sensitivity to brassinolide, thus speeding the launch of Instead, the brassinolide receptor, called BRI1, adopts defensive strategies against invading microbial pests, a superhelix conformation that sequesters the hormone He adds.—SARAH EVERTS
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NATURE
STRUCTURE OF BRASSINOLIDE’S RECEPTOR SOLVED
The protein that detects the plant hormone brassinolide adopts an unexpected superhelix conformation.
PHARMACEUTICALS Merck deal with South Korea’s Hanwha bolsters move into biosimilars Merck & Co. has agreed to pay South Korea’s Hanwha Chemical up to $720 million for access to HD203, a biosimilar form of Amgen’s arthritis and psoriasis treatment Enbrel. The deal buttresses Merck’s ambition to become a leader in the market for biosimilars, which are generic versions of biologic drugs. Last year, Enbrel logged $3.3 billion in sales in the U.S., where it will lose patent protection in October 2012. HD203 is in a Phase III study in Korea to confirm its safety and therapeutic equivalence to Enbrel in treating people with rheumatoid arthritis. It has yet to be subject to clinical tests in the U.S.
Merck will run additional clinical trials for and manufacture HD203, and it intends to sell the drug in all countries outside of Korea and Turkey, where Hanwha retains marketing rights. Hanwha will receive an undisclosed up-front payment from Merck, as well as milestone payments. Hanwha could reap up to $720 million over the course of the pact, according to a financial filing from the South Korean firm. Merck has been working diligently to become a key player in the emerging biosimilars marketplace since launching Merck BioVentures, a unit dedicated to developing generic biologics, in late
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2008. The company wants to have five biosimilars in late-stage development in 2012, a goal that it hopes to achieve with the aid of partnerships and ac qui si tions. The deal-making kicked off in 2006, with the acquisition of GlycoFi, a small biotech firm with technology to make glycosylated proteins in yeast. In 2009, Merck licensed generic versions of Ne upogen and Neulasta, a pair of Amgen chemotherapy adjuncts, from Insmed. And earlier this year, Parexel agreed to provide clinical development services for biosimilar candidates being developed by Merck.—LISA JARVIS
