Novel Protein Evolved?
Over at Uncommon Descent they are discussing a paper published in Genetics which presents evidence for a novel coding protein in the yeast S. cerevisiae. You can read UD’s post here, and the paper’s abstract here. Unfortunately a subscription to Genetics is required to read the whole paper.
Essentially, the researchers report that they have found a sequence in the yeast species S. cerevisiae which codes for an entirely new protein. While the protein itself has not been identified, the researchers say their study shows that it is likely part of a DNA repair pathway — processes in the cell that repair damaging mutations.
The primary evidence for the gene’s novelty rests on the fact that it lacks any homologues, or similar gene sequences, in related species. Homology is considered a sign of an evolutionary relationship. Thus the lack of a homologous gene in a closely related species indicates that the gene was produced only in the particular species that has it, and was not inherited.
If this is correct, it would be evidence in favor of the power of evolution to produce entirely new genes — evidence which has heretofore been lacking. While there is substantial evidence for the production of new genes by duplicating, shortening, shuffling, and recombining previously existing segments of genes, evidence for the formation of entirely new genes is sparse. Critics of Darwinian evolution have pointed to this fact, and to the prohibitive mathematical improbability of new genes forming by chance, as evidence against Darwin’s theory. This new study, however, would seem to indicate that this species was able to evolve an entirely new protein from a previously non-protein-coding segment of DNA.
The authors make some assumptions that need to be backed up by further experimentation, as noted by poster gpuccio at UD, namely: first, that the sequence actually codes for a functioning protein; and second, that the lack of homology is evidence for de novo evolution. (There are other biological explanations that could also apply).
It will take time to see what light further experimentation sheds on these results and their reliability.
May 28, 2008 at 3:21 am
Well, I’m Catholic. So I don’t have any problem with God choosing to use evolution as a means of creating. It is interesting, though.
I don’t think beer drinkers would mind finding that their beer yeast was giving them a novel and useful protein. (Any bodybuilders reading?) Then again, it’s probably lost in the filtration anyway.
May 28, 2008 at 3:49 am
Naive:
You’re right, there isn’t necessarily any theological problem here at all for Catholics. Instead of assuming that Darwin works, though, studies like this are interesting because they give us hard science to prove, or challenge, Darwin’s thesis.
A couple points of clarification. Proteins are not only the molecules that build up muscle mass, they are the very machinery of the cell. If you think of the cell as a complicated automated factory, proteins are like the robots on the assembly lines. Almost every process you can think of in the cell is carried out by proteins, including building muscles.This protein in the yeast has nothing to do with muscle mass. Also, the protein in the study would only be useful to the yeast themselves, not to someone who consumed them.
And yes, good catch. S. cerevisiae is a yeast used in fermentation. It’s also used for baking bread.
May 29, 2008 at 3:55 am
Yes, yes… cell repair.
So it sounds like they are reporting that they found a new gene that codes for a new protein, but your text sounds as if they haven’t verified “that the sequence actually codes for a functioning protein.” Isn’t that putting the cart before the horse?
Also, I’ve heard people say they could believe evolution as an explaination of minor modifications of a species adapting to its local environment, but that there isn’t any evidence of evolution leading to new species. If this is a new gene, would this be a (small) step in the direction of evolution as a means of generating new species? Or would this still be along the lines of specialization within a species? Would we need to know the function or usefulness of the protein itself to make that determination?
May 31, 2008 at 12:11 am
Naive,
From what I can deduce from the abstract and from other’s commentaries, without having read the paper myself, the researchers have strong indications that the sequence likely codes for a protein — recognizable sequences, assays, etc.. Isolating the protein itself and confirming that it really is expressed would seem to be the next step of research.
I think the greater area of interest in this study is its assumption that the appearance of the gene can be explained by traditional evolution. According to the commentary I’ve read, the sequence is conserved in other yeast species, but not expressed as far as we know, so at first glance to me it seems suspiciously ripe for mutation into a functioning gene. That’s an intriguing fact that I’d like to see investigated.
As far as your second point, I would recommend Mike Behe’s book “The Edge of Evolution” In it he attempts to look at the evidence for just how evolution can take us, and comes to the conclusion that its not very far.
This study, if confirmed, could be a step towards proof of evolution’s ability to produce new species. So far evolution has never been observed to produce a novel protein. This study indicates a possible case of that. But even if it is confirmed, there’s still a big difference between an S. cerevisiae generating a single new protein and an S. cerevesiae turning into an elephant. It would be an important piece of evidence, but not revolutionary.
So in my opinion this study is another small clue that needs to be worked into the bigger picture of all that we don’t know about organisms changing over time.