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Novel RNA and peptide species thought to have sparked evolution of complex life


The emergence of “information-coding properties”:

According to a new concept by LMU chemists led by Thomas Carell, it was a novel molecular species composed out of RNA and peptides that set in motion the evolution of life into more complex forms…

Ludwig Maximilian University of Munich, “The origin of life: A paradigm shift” at Phys.org (May 12, 2022)

It’s a new twist on the RNA world hypothesis:

“The RNA world idea has the big advantage that it sketches out a pathway whereby complex biomolecules such as nucleic acids with optimized catalytic and, at the same time, information-coding properties can emerge,” says LMU chemist Thomas Carell. Genetic material, as we understand it today, is made up of double strands of DNA, a slightly modified, durable form of macromolecule composed of nucleotides.

However, the hypothesis is not without its issues. For example, RNS is a very fragile molecule, especially when it gets longer. Furthermore, it is not clear how the linking of RNA molecules with the world of proteins could have come about, for which the genetic material, as we know, supplies the blueprints. As laid out in a new paper published in Nature, Carell’s working group has discovered a way in which this linking could have occurred.

Ludwig Maximilian University of Munich, “The origin of life: A paradigm shift” at Phys.org (May 12, 2022)

The new proposal:

According to the new theory, a decisive element at the beginning was the presence of RNA molecules that could adorn themselves with amino acids and peptides and so join them into larger peptide structures. “RNA developed slowly into a constantly improving amino acid linking catalyst,” says Carell. This relationship between RNA and peptides or proteins has remained to this day. The most important RNA catalyst is the ribosome, which still links amino acids into long peptide chains today. One of the most complicated RNA machines, it is responsible in every cell for translating genetic information into functional proteins. “The RNA-peptide world thus solves the chicken-and-egg problem,” says Carell. “The new idea creates a foundation upon which the origin of life gradually becomes explicable.”

Ludwig Maximilian University of Munich, “The origin of life: A paradigm shift” at Phys.org (May 12, 2022)

Sure it works if we are not looking for something simple enough to have evolved randomly by Darwinian processes. Something else must underlie the drive for complexity (“information-coding properties”) described here.

The paper is open access.

This proposed scheme presupposes an already existing self-replicating RNA world, which is a pipe dream. So it's a pipe dream within a pipe dream. From an article in the scientific journal Chemistry World by one organic chemist with a little sense, even though it turns out that he still thinks there just must be a way out for unintelligent undirected processes. It's just that the researchers haven't had enough time. ( https://www.chemistryworld.com/opinion/flaws-in-the-rna-world/4011172.article#commentsJump )
"It’s an alluring picture – catalytic RNAs appear by chance on the early Earth as molecular replicators that gradually evolve into complex molecules capable of encoding proteins, metabolic systems and ultimately DNA. But it’s almost certainly wrong. For even an RNA-based replication process needs energy: it can’t shelve metabolism until later. And although relatively simple self-copying ribozymes have been made, they typically work only if provided with just the right oligonucleotide components to work on. What’s more, sustained cycles of replication and proliferation require special conditions to ensure that RNA templates can be separated from copies made on them. Perhaps the biggest problem is that self-replicating ribozymes are highly complex molecules that seem very unlikely to have randomly polymerised in a prebiotic soup. And the argument that they might have been delivered by molecular evolution merely puts the cart before the horse. The problem is all the harder once you acknowledge what a complex mess of chemicals any plausible prebiotic soup would have been. It’s nigh impossible to see how anything lifelike could come from it without mechanisms for both concentrating and segregating prebiotic molecules – to give RNA-making ribozymes any hope of copying themselves rather than just churning out junk, for example. In short, once you look at it closely, the RNA world raises as many questions as it answers. Even one of the RNA world's chief advocates, Gerald Joyce of the Scripps Research Institute in California, suggested recently that it might be necessary to consider that the RNA world was preceded by ‘some other replicating, evolving molecule’ such as peptide-nucleic acid hybrids. That, of course, may simply defer some of the problems rather than solving them."
"RNA is a very fragile molecule". :) Fred Hickson
:) Fred Hickson
"Novel RNA and peptide species thought to have sparked evolution of complex life" OK, thought by whom? I bet there are a lot of other people who think differently! It's nice to have beliefs and ideas about how something might have happened, but how can you test this? If you can't test it, is it really science? What good is an untestable "hypothesis"? tjguy
This sort of thing is just trying to get a message across. The wrong message. relatd
RNA improved slowly into a machine that could improve slowly into a machine that could improve slowly... The silliness is so blatantly obvious. Sometimes I wonder if the writers are intentionally emphasizing it as a quiet message. Probably not. They're just stuck inside a loop and can't see the loop. polistra
"It is not clear" = "we have absolutely no idea" EvilSnack

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