Introns and Metazoans again

Recall that I hypothesized that introns have played a key role in facilitating metaozoan evolution.  Here’s some more support support for that hypothesis:

Quantifying the mechanisms of domain gain in animal proteins.

Buljan M, Frankish A, Bateman A.

Genome Biol. 2010;11(7):R74.

BACKGROUND: Protein domains are protein regions that are shared among different proteins and are frequently functionally and structurally independent from the rest of the protein. Novel domain combinations have a major role in evolutionary innovation. However, the relative contributions of the different molecular mechanisms that underlie domain gains in animals are still unknown. By using animal gene phylogenies we were able to identify a set of high confidence domain gain events and by looking at their coding DNA investigate the causative mechanisms.

RESULTS: Here we show that the major mechanism for gains of new domains in metazoan proteins is likely to be gene fusion through joining of exons from adjacent genes, possibly mediated by non-allelic homologous recombination. Retroposition and insertion of exons into ancestral introns through intronic recombination are, in contrast to previous expectations, only minor contributors to domain gains and have accounted for less than 1% and 10% of high confidence domain gain events, respectively. Additionally, exonization of previously non-coding regions appears to be an important mechanism for addition of disordered segments to proteins. We observe that gene duplication has preceded domain gain in at least 80% of the gain events.

CONCLUSIONS: The interplay of gene duplication and domain gain demonstrates an important mechanism for fast neofunctionalization of genes.

Question to think about: Is there any evidence to indicate that something like a mouse could have evolved without introns?

Advertisements

10 responses to “Introns and Metazoans again

  1. Without introns the designer(s) would just need some other method of separating genic sequences. But without alternative gene splicing and overlapping genes the size of the genome to account for all the required proteins would most likely bust the nucleus.

  2. Question to think about: Is there any evidence to indicate that something like a mouse could have evolved without introns?

    Not from this article.

    But I have my own question. The article states:
    Additionally, exonization of previously non-coding regions appears to be an important mechanism for addition of disordered segments to proteins.

    I’m not sure I understand what they’re saying, but it sounds like they’re saying that parts of introns became exons, and that this was an important mechanism for making new proteins? Do I have that right?

  3. I’m not sure I understand what they’re saying, but it sounds like they’re saying that parts of introns became exons, and that this was an important mechanism for making new proteins? Do I have that right?

    Yep. This is another blow to those who argue “natural processes cannot generate information.”

  4. Michael:

    This is another blow to those who argue “natural processes cannot generate information.”

    But who makes that argument? The argument is blind, undirected processes cannot create information from scratch nor can they increase information. Also I would say that in any front-loading scenario the information for making new proteins from existing material would be front-loaded meaning when such a thing happens it isn’t an increase and it isn’t new.

  5. As an aside- For Christmas I got my daughter one of these (could be a twin)- but it ain’t quackin’- any ideas on how to fix it?

    On thing is for sure- I ain’t eating coco-puffs again…

  6. If it ain’t quackin, don’t fix it. Now that’s a great gift. Did she like it?

  7. Yes, she loves it- we let “thumper” have the run of the house when we are home.

    I never knew rabbits were so cool…

  8. This is another blow to those who argue “natural processes cannot generate information.”

    It would be interesting to know how many mutations were needed to create the new proteins.

  9. Bilbo,

    Part of the issue will be to get a binding site- the proper biding site- for the new DNA sequence. IOW even if you get a DNA sequence that has a start codon, proper nuleotide sequencing (for correlation to amino acids) and all else required, it still needs a binding site for expression. Then you need a way to stop the expressing, which, I believe, is another binding site.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s