Origins of life? Discovery could help explain how first organisms emerged on Earth

Apr 05, 2013 by Doug Carlson
Researcher offers clues on the origins of life
Michael Blaber, a professor in Florida State's College of Medicine.

(Phys.org) —A structural biologist at the Florida State University College of Medicine has made discoveries that could lead scientists a step closer to understanding how life first emerged on Earth billions of years ago.

Professor Michael Blaber and his team produced data supporting the idea that 10 amino acids believed to exist on Earth around 4 billion years ago were capable of forming foldable proteins in a high-salt (halophile) environment. Such proteins would have been capable of providing for the first living organisms to emerge on the planet between 3.5 and 3.9 billion years ago.

The results of Blaber's three-year study, which was built around investigative techniques that took more than 17 years to develop, are published in the journal Proceedings of the National Academy of Sciences.

The first would have been microscopic, cell-like organizations capable of replicating and adapting to environmental conditions—a humble beginning to on Earth.

"The current paradigm on the emergence of life is that RNA came first and in a high-temperature environment," Blaber said. "The data we are generating are much more in favor of a -first view in a halophile environment."

The widely accepted view among scientists is that RNA, found in all living cells, would have likely represented the first molecules of life, hypothesizing an "RNA-first" view of the origin of living systems from non-living molecules. Blaber's results indicate that the set of amino acids produced by simple chemical processes contains the requisite information to produce complex folded proteins, which supports an opposing "protein-first" view.

Another prevailing view holds that a high-temperature (thermophile) environment, such as deep-ocean , may have been the breeding ground for the origin of life.

"The halophile, or salt-loving, environment has typically been considered one that life adapted into, not started in," Blaber said. "Our study of the prebiotic amino acids and protein design and folding suggests the opposite."

Without the ability to fold, proteins would not be able to form the precise structures essential for functions that sustain life as we know it. Folding allows proteins to take on a globular shape through which they can interact with other proteins, perform specific chemical reactions, and adapt to enable organisms to exploit a given environment.

"There are numerous niches that life can evolve into," Blaber said. "For example, extremophiles are organisms that exist in high temperatures, high acidity, extreme cold, extreme pressure and extreme salt and so on. For life to exist in such environments it is essential that proteins are able to adapt in those conditions. In other words, they have to be able to fold."

Comet and meteorite fragments, like those that recently struck in the Urals region of Russia, have provided evidence regarding the arrival of amino acids on Earth. Such fragments predate the earth and would have been responsible for delivering a set of 10 prebiotic (before life) amino acids, whose origins are in the formation of our solar system.

Today the human body uses 20 common amino acids to make all its proteins. Ten of those emerged through biosynthetic pathways—the way living systems evolve. Ten—the prebiotic set—can be made by chemical reactions without requiring any living system or biosynthetic pathway.

Scientific evidence exists to support many elements in theories of abiogenesis (the ), including the time frame (around 3.5 to 3.9 billion years ago) and the conditions on Earth and in its atmosphere at that time. Earth would have been made up of volcanic land masses (the beginning of the formation of continents), salty oceans and fresh-water ponds, along with a hot (around 80 degrees Celsius) and steamy atmosphere comprising carbon dioxide and nitrogen. Oxygen would have come later as a by-product of green plant life and bacteria that emerged.

Using a technique called top-down symmetric deconstruction, Blaber's lab has been able to identify small peptide building blocks capable of spontaneous assembly into specific and complex protein architectures. His recent work explored whether such building blocks can be comprised of only the 10 prebiotic amino acids and still fold.

His team has achieved foldability in proteins down to 12 —about 80 percent of the way to proving his hypothesis.

If Blaber's theory holds, scientists may refocus where they look for evidence in the quest to understand where, and how, life began.

"Rather than a curious niche that life evolved into, the halophile environment now may take center stage as the likely location for key aspects of abiogenesis," he said. "Likewise, the role of the formation of proteins takes on additional importance in the earliest steps in the beginnings of ."

Explore further: Microbes provide insights into evolution of human language

More information: www.pnas.org/content/110/6/2135.full.pdf+html

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PhotonX
4.3 / 5 (11) Apr 05, 2013
Is it just me, or does this guy look like Fred Willard?

Another prevailing view holds that a high-temperature (thermophile) environment, such as deep-ocean thermal vents, may have been the breeding ground for the origin of life. "The halophile, or salt-loving, environment has typically been considered one that life adapted into, not started in," Blaber said. "Our study of the prebiotic amino acids and protein design and folding suggests the opposite."
I had always assumed that if the hydrothermal vent theory panned out, that would by definition be a salty environment. Was that not the case?

Off Topic: Meanwhile, (at risk of starting another flame war) maybe we can get finally get the fundamentalists to buy into abiogenesis if we can convince them that halophilic means "halo-loving".
Steven_Anderson
3.2 / 5 (13) Apr 05, 2013
You will never get anyone who believes in the instantaneous creation of the universe to believe otherwise. It would cause them to feel insignificant and meaningless. Religion gives people a sense of purpose and meaning as well as a disparity between the us and them that enhases those feelings. To suggest that they were created without a direct purpose and in a deliberate fashion would take away from the comfort that such beliefs give them. The commradery/socialization that it brings is an ingrained survival instict that has probably developed over a million years, it will take at least that long for humans to evolve from it if ever. http://rawcell.com
Tim_Riches
4.2 / 5 (9) Apr 05, 2013
Here's hoping that the creationists who jump on this news will finally understand the difference between evolution and abiogenesis!
humy
4.3 / 5 (4) Apr 06, 2013
Their theory seems to be here that the first life had protein only i.e. no RNA and, I presume, no RNA-like molecules. But wouldn't that mean the first cells would have no genes to pass on their characteristics to their offspring i.e. the next generation of cells? -surely this would mean they could not evolve via mutation and natural selection and thus evolve into more advanced life!
So, unless I am missing something, the 'protein-first' hypothesis is flawed and only the 'RNA-first' or at least 'RNA-like-first' (the first genes may have been made of molecules that were RNA-like and then later evolved into RNA) hypothesis is valid.
Am I missing something here?
Any comments?
JES
4 / 5 (4) Apr 06, 2013
Wonder how long it'll take before this string end up in a religious debate..:-)
LarryD
1.4 / 5 (7) Apr 06, 2013
Wonder how long it'll take before this string end up in a religious debate..:-)

Yes, I rather think it will. I am not religious but I'm sure someone will point out that the conditions for protein folding is a long long way life as we know it. The other point will be be '...His team has achieved foldability in proteins down to 12 amino acids—about 80 percent of the way to proving his hypothesis...'
There must be a lot of theories 'out there' that are 50%, 60%, 70%, 80% and maybe even 90% proof but I'm not sure what THAT really means. For example, one camp could say that of the small % of UFO reports that cannot be explained, 90% of these is proof that they are from elsewhere in the cosmos. The opposite camp would argue that because 95% (say) of UFO reports are mundane this is proof that they are(say) mis-identification.
I don't think Professor Blaber should have made that % quote as it could mean that a lot of good, hard work will get a thumbs down by many.
robert_sommerfelt_3
5 / 5 (2) Apr 06, 2013
Their theory seems to be here that the first life had protein only i.e. no RNA and, I presume, no RNA-like molecules. But wouldn't that mean the first cells would have no genes to pass on their characteristics to their offspring i.e. the next generation of cells?


Blaber's ground-breaking findings is not a full explanation of biogenesis all up to the level of information-carrying nucleotides, he's merely hypothizing that perhaps large (or sufficient) volumes of these proteins may have been formed as a first crucial step. Note that the ten amino acids "can be made by chemical reactions without requiring any living system or biosynthetic pathway". So once you have a "mass" of these that form enough foldable proteins, this semi-living mass may have formed a platform for the next "step", namely incorporation of nucleotides (RNA).

verkle
1.3 / 5 (14) Apr 06, 2013
I don't know why some scientists fear religion. Christianity is very much pro-science. The two do not occlude each other. Many of the finest scientists in history have been Christians.

humy
4.5 / 5 (8) Apr 06, 2013
I don't know why some scientists fear religion.


Its usually just the creationists the scientists really don't like (and any other anti-science religious stances) rather than Christianity in the generic sense.
Darwin was a christian but later turned into an agnostic after he discovered evolution.
ValeriaT
1 / 5 (3) Apr 06, 2013
The current paradigm on the emergence of life is that RNA came first and in a high-temperature environment
The RNA is useless by itself. It's quite apparent, that the inheritance mechanism has no meaning if there is nothing to inherit.
jsdarkdestruction
4.2 / 5 (5) Apr 06, 2013
I don't know why some scientists fear religion. Christianity is very much pro-science. The two do not occlude each other. Many of the finest scientists in history have been Christians.


Fear and contempt are 2 different things.
You are correct. Their are some good scientists who are christian out there and have been in the past too but heres the crucial difference, unlike you they dont take their storybook as literal truth and say any science that contradicts it must be wrong because science fears religion and all that other nonsense you spew. A persons religion has no bearing in scietific discussion. Who cares some of the greatest scientists were christians? how does that mean that your fairy tale must be true?
aroc91
5 / 5 (3) Apr 06, 2013
The current paradigm on the emergence of life is that RNA came first and in a high-temperature environment
The RNA is useless by itself. It's quite apparent, that the inheritance mechanism has no meaning if there is nothing to inherit.


RNA can be catalytically active. Look up ribozymes.
Torbjorn_Larsson_OM
5 / 5 (5) Apr 06, 2013
Right now all the phylogenetic work points to alkaline hydrothermal vents as the origins of cells. The chemical evolutionary pathways are homologous with early autotrophic metabolism, and the H /Na usage in early proteins is directly derivable from protocell membranes in such environments. Likewise protein fold family trees shows these proteins before all RNA handling is in place.

But there is still need for a hybrid protein/RNA scenario to manage these first genes. Blaber's works fits nicely into such a framework, and if vents are not extra haline environments I don't know what is.

@PhotonX: Indeed.
Torbjorn_Larsson_OM
5 / 5 (5) Apr 06, 2013
@humy: There are protein first scenarios, like the Protein Pump (chemically evolved small proteins aseembled in wet-dry cycles on the beaches of oceans). But they are not biologically motivated and so not surprisngly don't fit well with biological probing of early cells (see above).

The coupling between chemical and biological evolution is a different problem. RNA will thermodynamically be forced to crystallize a population of replicating strands in an environment of phosphate activated nucleotides. (Aka alkaline hyrothermal vents.) When enclosed by protocell membranes (which forms spontaneously, given lipids produced in such vents) such a population will proceed by darwinian evolution.

The reason is that they compete for lipids, and the largest cell, the one with the fastest growing replicator population inside, is fitter. (And when above a certain size divides spontaneously in daughter cells.) So that starts on the replicator level.
Torbjorn_Larsson_OM
5 / 5 (5) Apr 06, 2013
[cont] The pathway between replicators and genes are legion, but the simplest, most likely one, is by evolving a RNA strand division chaperone that makes division less coupled to the initial hot-cold cycling of vent streams and so more robust. The chaperones becomes the first genes.

In fact, the same pathway predicts why the early fold families are filled with random sequences. The next step to speed up reading (and eventually free RNA reading from vent heat requirements) was the formation of a minimal brownian ratchet that kept the separating strands apart while moving unidirectionally. Such a ratchet is, uniquely, protein strand formation with 3 nucleobases for each ratchet lock (amino acid).

But filling a cell with random protein junk has its problems, so protein recycling (metabolism) was early functional genes.

@LarryD: Blaber is likely referring to minimal length proteins that can occur more or less spontaneously on clay surfaces in the presence of amino acids.
Torbjorn_Larsson_OM
5 / 5 (6) Apr 06, 2013
@verkle: Creationists shouldn't comment on science, it is hilarious and makes deconverts from religion, see Dawkins's Convert's Corner.

Scientists don't fear religion, they mostly ignore it. Religion is completely incompatible with science, as religion is in the business to replace facts with belief and science is in the business to replace belief with facts. Very few scientists are religious, when you look at the best scientists almost 100 % are atheists. This is because education makes agnostics of religious and atheists of agnostics.

Nowadays they are so openly incompatible that religious scientists can be characterized as competent technicians at best, as they ignore the skepticism used elsewhere in their research.

And yes, that is why religion "occludes" (obstructs) science, it tries to destroy it with religious lies like "creationism". It didn't happen, and we know that. The inflationary universe started out too hot so lifeless, and now there is life after chemical evolution.
jibbles
not rated yet Apr 06, 2013
Their theory seems to be here that the first life had protein only i.e. no RNA and, I presume, no RNA-like molecules.
...
Am I missing something here?
Any comments?


i think even the rna-first hypothesis didn't go right to reproducing cells whose genes were encoded in their rna, but rather.
this is a stage of life consisting of homeostatic molecular nano-environments. the information would have been more diffuse, diverse, replication -- imprecise, and reproduction -- simple propagation.

these nano-enviroments would probably have recursively formed sophisticated communities that could perform homeostasis on ever larger environments and propagate on ever larger scales -- still without a relying a universal molecule to encode their propagation.

the emergence of a r.n.a. and d.n.a. as a formal coding media probably began to take hold from the bottom up, when a macroenvironment's success began to depend on the very precise propagation (i.e. replication) of some subenvironment...
jibbles
not rated yet Apr 06, 2013
as more and more sub-environments within a community began replicate, d.n.a. eventually won out as the most robust unified code for community protein synthesis.
jibbles
not rated yet Apr 06, 2013
i've some people in fact believe that d.n.a. was originally parasitic. kinda like a virus infecting micro-environments. it's long term success depended on its becoming symbiotic.

i think it's a beautiful view.

anyhow d.n.a and even r.n.a. as coding mechanisms did not have to arise concurrently with life.
humy
5 / 5 (1) Apr 07, 2013
i've some people in fact believe that d.n.a. was originally parasitic. kinda like a virus infecting micro-environments. it's long term success depended on its becoming symbiotic.

Interestingly, I had independently wondered about that and speculated on the possibility that billions of lifeless microspheres, the precursors to the first photocells, that spontaneously formed in tidal pools, could have been 'infected' and 'parasitized' by strands of RNA or at least RNA-like molecules. Then, later, some of these 'RNA viruses' evolved to have a symbiosis with some of these lifeless microspheres so to, in effect, give them 'life' and the ability to reproduce and evolve. This would be a kind of virus-first living-cells-later hypothesis. Don't know how likely this is.
italba
3 / 5 (8) Apr 07, 2013
Incredible, a good scientific discussion on PhysOrg! Maybe religious trolls don't works on Sundays?

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