VPg

[Lyle Najita]

In article <9505220121.AA25841 at phobos.med.pitt.edu>, bap at MED.PITT.EDU
(Bruce Phillips) wrote:

>         The cellular enzyme that cleaves VPg from the 5' uridine on the
> picornaviral RNAs attacks the phosphodiester bond, as shown by Baltimore's
> group some years ago.  I'm sure I can locate the reference if anyone is
> interested.  Therefore, the enzyme is not a protease.  Rather, it
> specifically hits the bond linking the terminal uridylic acid to the
> tyrosine which resides somewhere in the middle of the VPg peptide.
> 
>         I agree that there are some neat experimental approaches that could
> be focused on the problem, one that just might not be trivial.  Anyone think
> NIH would fund such a project, especially after the Republican-initiated
> 25% cut to NIH?

You are indeed correct, I actually dug back and found the Ambrose and
Baltimore reference. It is clear that the unlinkase activity is not a
protease, however it could be a type I phosphodiesterase. I'm not well
versed in these types of enzymes, but the cobra venom phosphodiesterase
was used in the characterization by Ambrose and Baltimore.

As for the experimental aspect, I was saddened to hear that Baltimore was
giving up his polio research. As my thesis advisor suggested as long as
polio was important enough for him to work on, it was still very much
worth funding. Given that every time I talked to people about my thesis
work the response was, "Oh, I thought they cured polio years ago.", I
doubt that the same level of funding will be available in the future.

L
My opinions are my own, at least, that's what they tell me.