Friday, April 14, 2006

Nylonase

Three preliminary thoughts about this story....

1. Generally mobile DNA elements are very strange things and have few good reviews available freely on the internet. We seem to know rather little about their origin and function.

2. Given its importance in the evolution debate the nylonase story has been poorly served with regard to review articles on the web (unless I have missed all the good ones). The original papers are not very clearly written. I would have expected a really good review of the primary literature somewhere... if you know such a review I would be very grateful to have it.

3. Maybe it is just me ...but it is a very weird story. The idea that a block of multiple repeats should code an enzyme just waiting to line up with a promoter by means of a frameshift mutation for its expression is rather strange to me and makes me want to do experiments asking how many different types of multiple repeats will produce a viable enzyme for this reaction. The author of the paper proposing this mechanism for brand new enzyme function production expresses his surprise that so rapid a sequence divergence could occur between the two variants of the enzyme 11.35% amino acid sequence divergence:

"so extensive an amino acid sequence divergence is not expected to occur in so short a time span- ie 40 years or thereabout."

4 Comments:

Blogger Lifewish said...

Well, there's this one, but I'm guessing you've already found that. I'll put studying nylonase on my ever-lengthening "to do" list...

What would you expect a good review article on this subject to cover?

11:15 am  
Blogger Tim Hague said...

There is also this article:

http://www.talkorigins.org/origins/postmonth/apr04.html

which rips to shreds an 'Answers in Genesis' piece while giving quite a good overview of nylonase enzymes at the same time...

4:06 pm  
Blogger Tim Hague said...

I'll try that link again:

here

4:07 pm  
Anonymous Anonymous said...

I have just had a look at the talk origins post, and the guy is a clever writer, but a poor scientist.
E.g. "not only is the nylon polymer not found in nature, neither are the linkages that bind the subunits together".
The nylon certainly has not been found in nature, but the 2nd statement shook my faith in my chemisty education. I thought that nylon was linked by amide (peptide) linkages. Sure enough, a quick check on Wikipedia restored my faith.
The funny thing is that all proteins are linked together by peptide bonds, hence the term "polypeptide". Would a non-scientist have been able to discern this though?
From the rest of the post I gained the impression that he was trying to make the creationist look foolish, rather than trying to elucidate nylonase and the details of molecular evolution.
As far as I can tell, nylonase is an example of adaptive molecular recognition, such as is found in the immune system, which would explain why it "evolved" so quickly: because the system of transposable elements (whose relocations are partly random, but also in fact considerably constrained by marker sequences) that assembles it is so elaborate, the information gap is small enough to be crossed by chance.
Thus "mindless" evolution works in this case. However, it just highlights a technology behind it that is still far beyond human technology. That is the pattern in molecular biology. That is why ID makes sense.
Andrew

11:57 pm  

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