Monday, July 31, 2006

VSV contradicts evolution?

I personally don't find structure papers very interesting. I bet they are facinating if you are in the field, however, for biology they seem to have little relevance. I ran accross this great article in Science talking about the recent crystal structure of the VSV glycoprotein (AAAS access required) and how it is way too similar to a glycoprotein from HSV. Apparently this raises questions about virus evolution because VSV and HSV are nothing alike, except apparently in the three dimensional structure of one protein that contains is no amino acid sequence similarity. I couldn't believe they didn't even mention the possibility of some sort of convergent evolution. They do say something about 'gene capture', something I've never heard of but assume they are speaking of horizontal gene transfer.
BTW blogger is terrible and not uploading images.


Bayman said...

Yeah I noticed that too...after all selection acts on genes which encode amino acids in proteins which specifies the tertiary structure, not vice versa. So if they got no homology on the primary level, that implies convergent evolution. To suggest a common ancestor you'd have to see some homology at the amino acid level. Wait...I just blasted and they both have methionines at position 1...This is why stuctural biologists should be barred from making functional speculation in their papers!! Just proof of what Rob says, crystal structures are good for pretty pictures and SDM and not much else....

rob said...

Of course you could argue that it is the structure/function that is selected for and once a structure/function is obtained you get amino acid sequence drift from the origonal.
Also if you look at the pics they do share some similarity but only a structural biologist would have the skillz to know if it is significant at all. I know nothing about structural homology that isn't sequenced based.
In any case I think a common ancestor for VSV and HSV is pretty improbabe.