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Life’s First Spark Re-Created in the Laboratory

A fundamental but elusive step in the early evolution of life on Earth has been replicated in a laboratory.

Researchers synthesized the basic ingredients of RNA, a molecule from which the simplest self-replicating structures are made. Until now, they couldn’t explain how these ingredients might have formed.

“It’s like molecular choreography, where the molecules choreograph their own behavior,” said organic chemist John Sutherland of the University of Manchester, co-author of a study in Nature Wednesday.

RNA is now found in living cells, where it carries information between genes and protein-manufacturing cellular components. Scientists think RNA existed early in Earth’s history, providing a necessary intermediate platform between pre-biotic chemicals and DNA, its double-stranded, more-stable descendant.

Like other would-be nucleotide synthesizers, Sutherland’s team included phosphate in their mix, but rather than adding it to sugars and nucleobases, they started with an array of even simpler molecules that were probably also in Earth’s primordial ooze.

They mixed the molecules in water, heated the solution, then allowed it to evaporate, leaving behind a residue of hybrid, half-sugar, half-nucleobase molecules. To this residue they again added water, heated it, allowed it evaporate, and then irradiated it.

At each stage of the cycle, the resulting molecules were more complex. At the final stage, Sutherland’s team added phosphate. “Remarkably, it transformed into the ribonucleotide!” said Sutherland.

According to Sutherland, these laboratory conditions resembled those of the life-originating “warm little pond” hypothesized by Charles Darwin if the pond “evaporated, got heated, and then it rained and the sun shone.”

Such conditions are plausible, and Szostak imagined the ongoing cycle of evaporation, heating and condensation providing “a kind of organic snow which could accumulate as a reservoir of material ready for the next step in RNA synthesis.”

Intriguingly, the precursor molecules used by Sutherland’s team have been identified in interstellar dust clouds and on meteorites. (Source-Wired)

It’s a fascinating development. We may not find a practical application of this information that’s acceptable to everyone any time soon, but just knowing that there is a reasonable explanation for the beginning of life is worthwhile.

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• Life’s First Spark Recreated in the Laboratory (wired.com)
• Mystery of how life on Earth began solved by British scientists (telegraph.co.uk)
• Primordial goo (kottke.org)
• How RNA Got Started: Scientists Look for the Origins of Life (usnews.com)
• RNA research sheds light on first life forms (seattletimes.nwsource.com)

Scientists find missing evolutionary link using tiny fungus crystal

Creationists like to latch on to minor points to try and make major claims. One of the more popular latch points for them is the transition from single cell, or simple, lifeforms to the more complex, multicellular forms. Since up until now science has not had a ready explanation for that jump, creationists and the ID crowd want to assume that god must have been responsible. It does no good to tell these people that just because we don’t have an answer to the “how” in many of nature’s processes this does not lead logically to a conclusion that “god did it”.

Well, now we are a bit closer to understanding that change from simple to complex life, and there’s still no sign of a god’s involvement.

The crystal structure of a molecule from a primitive fungus has served as a time machine to show researchers more about the evolution of life from the simple to the complex.

By studying the three-dimensional version of the fungus protein bound to an RNA molecule, scientists from Purdue University and the University of Texas at Austin have been able to visualize how life progressed from an early self-replicating molecule that also performed chemical reactions to one in which proteins assumed some of the work.

“Now we can see how RNA progressed to share functions with proteins,” said Alan Lambowitz, director of the University of Texas Institute for Cellular and Molecular Biology. “This was a critical missing step.”

Results of the study were published in Thursday’s (Jan. 3) issue of the journal Nature.

“It’s thought that RNA, or a molecule like it, may have been among the first molecules of life, both carrying genetic code that can be transmitted from generation to generation and folding into structures so these molecules could work inside cells,” said Purdue structural biologist Barbara Golden. “At some point, RNA evolved and became capable of making proteins. At that point, proteins started taking over roles that RNA played previously – acting as catalysts and building structures in cells.”

In order to show this and learn more about the evolution from RNA to more complex life forms, Lambowitz and Paul Paukstelis, lead author and a research scientist at the Texas institute, needed to be able to see how the fungus’ protein worked. That’s where Golden’s team joined the effort and crystallized the molecule at Purdue’s macromolecular crystallization facility.

“Obviously, we can’t see the process of moving from RNA to RNA and proteins and then to DNA, without a time machine,” Golden said. “But by using this fungus protein, we can see this process occurring in modern life.”

Looking at the crystal, the scientists saw two things, Golden said. One was that this protein uses two completely different molecular surfaces to perform its two roles. The second is that the protein seems to perform the same job that RNA performed in other simple organisms.

“The crystal structure provides a snapshot of how, during evolution, protein molecules came to assist RNA molecules in their biological functions and ultimately assumed roles previously played by RNA,” Golden said.

The rest of the article, and a cool animation of the crystal, at: http://news.uns.purdue.edu/x/2008a/080102GoldenEnzyme.html