Gas station without pumps

2016 September 23

Evolution of caffeine

Filed under: Uncategorized — gasstationwithoutpumps @ 13:07
Tags: , ,

PZ Myers has a nice discussion of the convergent evolution of the synthesis of caffeine (separately evolved at least 5 times!), based on the paper from PNAS, Convergent evolution of caffeine in plants by co-option of exapted ancestral enzymes, by Huang, O’Donnell, Barboline, and Barkman.

Biologists used to think that there was one canonical pathway for caffeine synthesis, from xanthosine through 7-methylxanthine and theobromine to caffeine.  The paper shows that some plants use a different pathway (through 3-methylxanthine and theophylline) and that the enzymes used even on the common pathways are different.

The evolutionary model that best explains the data is that ancestral enzymes were promiscuous (which means that they had several different functions, not that they were sexual) and were eventually duplicated and specialized for caffeine production.  The researchers reconstructed some of the ancestral enzymes from the modern descendants and confirmed that this hypothesis was reasonable, as only single amino-acid substitutions were necessary to confer the two different specificities of the modern enzymes from the ancestral ones.

Leave a Comment »

No comments yet.

RSS feed for comments on this post. TrackBack URI

Leave a Reply

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

You are commenting using your 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 )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: