'Evolved' ribozyme boosts view of RNA - C&EN Global Enterprise

May 22, 1995 - These specialized snippets are called "ribozymes," a term coined by their discoverer, Thomas R. Cech, a chemistry professor at the Univ...
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the journal will publish readers' com­ ments on published papers. All such comments will be published using the title of the original paper, followed by an appropriate addendum, such as Dis­ cussion, Correction, or Reply to Discus­ sion. This, Roy believes, will ensure that computerized searches will lead to a complete record including corrections and comments. He hopes that this fea­ ture "will restore some of the personal vitality to the literature." Roy, who is editor-in-chief of JMR, has assembled a "very distinguished" board of 20 editors from around the world to handle manuscripts. The journal will be published by World Scientific Publish­ ing in Singapore. He expects the first is­ sue of IMR to roll off the presses in July, followed by two or three more issues in 1995. The plan is to print six issues in 1996, and to go to monthly publication after that. By January 1996, Roy hopes the journal will be able to publish a pa­ per within two months. Of course, the publication schedule depends on what kind of reception the journal gets. "Frankly, I don't know whether we will be swamped or starved" in the beginning, Roy says. Submissions are just beginning to trickle in. Asked about the quality of the pa­ pers, Roy mentions one paper that is "first rate" and another that is on the borderline between "really innovative" and "weird." That could be a hint of what is to come. Timothy M. Swager, a materials chemist at the University of Pennsylvania, pre­ dicts that the new journal "will not be used by creditable scientists. It will most likely be the Natwnal Enquirer of the sci­ entific literature and will largely be used for amusement rather than dissemina­ tion of scientific information." This opinion is echoed by chemistry professor Charles M. Lieber of Harvard University: "Cold fusion is a perfect ex­ ample of a 'truly innovative and unex­ pected' result that would benefit from such a journal. The peer review system is not perfect [but] I have found that most scientists offer honest and constructive comments in these reviews, and I believe that such criticism ultimately leads to better scientific publications." Chemistry professor David M. Walba of the University of Colorado, Boulder, admits having "decidedly mixed feel­ ings" about IMR. "I am sympathetic to the basic idea of a fast-turnaround vehi­ cle for hot new results," he says. On the

other hand, if good materials work is not appearing in existing refereed journals, he adds, it may be up to the materials community to do a better job of refereeing for those journals. Other researchers contacted by C&EN also didn't see any particular need for this new journal. And they questioned whether someone with truly innovative results would prefer to publish them in a new journal that doesn't have an estab­ lished reputation. Roy has heard all this before: "They said exactly the same things when we started the first materials journal—the Materials Research Bulletin—in 1966 and when a group of us started the Materials Research Society in 1973. They both changed the culture of materials science." IMR is "an experiment," Roy contin­ ues. "Maybe it won't work." But if it does work, he hopes the idea "will catch on and spread" throughout the publica­ tions world. "That's my hope—that it'll save the [materials] community a lot of time and effort." Individual subscription rates for JMR start at $85. In the U.S., orders (and re­ quests for a complimentary issue) may be placed by calling (800) 227-7562. Ron Dagani

'Evolved' ribozyme boosts view of RNA Researchers in Boston and Santa Cruz, Calif., have discovered that RNA has the hidden ability to catalyze a critical bio­ logical reaction, bolstering the theory that RNA was the primary agent of life before DNA and proteins took over. RNA, or ribonucleic acid, a singlestranded nucleic acid chain, is best known for its role as DNA's messenger. But RNA molecules can also behave like enzymes, catalyzing reactions with them­ selves and other pieces of RNA. These specialized snippets are called "ribozymes," a term coined by their discoverer, Thomas R. Cech, a chemistry professor at the University of Colorado, Boulder. Cech received the 1989 Nobel Prize in Chemis­ try for his work on ribozymes. It is RNA's ability to assume both genetic and enzymatic duties that has led some researchers to propose that life began with RNA. In this scenario, early forms of RNA would have per­ formed the jobs of both DNA and pro­ teins, until these two separate molecu-

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SCIENCE/TECHNOLOGY

'Evolved'ribozymeself-alkylates by attack on biotin derivative

Tapping the unseen skills lar lineages evolved and eventually of ribozymes has now be­ usurped RNA. In today's biological world, RNA's come a favorite project of catalytic repertoire consists of only one some molecular biologists. group of reaction types, breaking and Among them, Szostak and making phosphorus-oxygen bonds in David P. Bartel developed the RNA backbone to cleave and paste an oligonucleotide ligase ri­ bozyme. Later, Szostak and itself or other RNA together. However, molecular biologists Charles Jon R. Lorsch also selected a Wilson and Jack W. Szostak at Massa­ ribozyme that behaved as a chusetts General Hospital in Boston may polynucleotide kinase. Peter have jogged in RNA a chemical memo­ G. Schultz and colleagues ry of long-dormant abilities. By means of have developed a ribozyme an accelerated test-tube "evolution," the that catalyzes noncovalent researchers produced a ribozyme that isomerization of a bridged can catalyze a wholly different type of biphenyl ring system. reaction—nitrogen-caibon bond forma­ Wilson and Szostak's tion [Nature, 374,777 (1995)]. work—with its departure This self-alkylation reaction is similar from nucleotide-containing to many essential biochemical reactions, substrates—demonstrates says Wilson, now a biology professor at one of the many new reac­ the University of California, Santa Cruz. tionsribozymesseem capable The reaction is also the first known in of, says Andrew Ellington, a which RNA binds to a non-nucleotide- chemistry professor at Indi­ ana University in Bloomingcontaining substrate. A few years ago, Cech and coworkers ton. 'Ifs another step on the at Colorado working in collaboration way to showing that RNA with Harry F. Noller, a molecular biolo­ can do darn near anything gy professor at UC Santa Cruz, devel­ that proteins can do," he Biottnylated ribozyme oped a ribozyme that could catalyze hy­ says. BIE = /^Ιο«ΓΚ>γμΝ'-Ιούοβοβίγμ·ίΗγΙβηβάΙβπιΐΓ * drolysis of an aminoacyl ester [Science, Wilson and Szostak have 256, 1420 (1992)]. "That wats probably moved into uncharted wa­ the first demonstration of [RNA] cataly­ ters, developing a threesis involving a carbon center, but the stage process of mutating and selecting Some of the ribozymes did perform problem was that catalytic enhancement RNA fragments, for which they have the catalysis, the researchers found. Wil­ was very small," Noller says. applied for a patent. Their funding is son and Szostak enhanced the reaction from the National Institutes of Health a million-fold with a third round. and Germany's Hoechst A.G. The implications for this ribozyme's Searching for a reaction to evolve into activity are interesting, Wilson notes. Three-step strategy RNA that did not involve nucleic acid Naturally occurring RNAs in biological 'evolves' ribozyme substrates, they settled on self-alkylation settings all undergo modifications— with a biotin derivative, because ri­ many of which involve alkylations—by Random RNA pool bozymes with this capability are easily enzymes after they are made. "The fact detected in the lab and enriched. Starting that [the test-tube ribozyme] can per­ Biotin affinity with a pool of some 500 trillion random form [the alkylation] itself suggests that chromatography RNA pieces, Wilson and Szostak selected the modifications may have been RNAthose that were "biotin-binding"—that catalyzed events, but were eventually had an affinity for biotin yet didn't actual­ taken over by proteins," he says. Biotin-binding RNAs ly form a true bond. They accomplished One limitation, Wilson says, is that the this with affinity chromatography using ribozyme was only able to carry out a Mutagenesis a biotin agarose matrix. After seven single turnover reaction. That is, the re­ Selection for rounds of selection, more than 50% of the action cycle ended after it modified it­ self-biotinylation RNA pool bound specifically to biotin. self, unlike protein enzymes, which cata­ lyze multiple rounds of reactions. Wil­ Next, this pool of biotin-binding Self-alkylating ribozymes RNA was randomly mutated, in hopes son's current project is to isolate RNAs that one of the mutations would en­ that catalyze multiple rounds of reac­ dow an RNA molecule with catalytic tions on external substrates, which Mutagenesis ability, rendering it a true ribozyme. would add still more evidence to the Repeat selection The researchers then searched for ri­ RNA-world theory. So far, Wilson says, bozymes that catalyzed self-alkylation that research is showing "encouraging Evolved ribozyme with the haloacetyl derivative N-biotin- results." oyl-N'-iodoacetyl-ethylenediamine. Elizabeth Wilson 28

MAY 22,1995 C&EN