Well that was interesting

It’s a closely-guarded secret that can now be revealed – on Friday, May 14, Steve Matheson and I served as the critics for an event at Biola University the focus of which Stephen Meyer and his book “Signature in the Cell”.  (Well, actually, this was the lead-in to some big hoopla about the release of a new Illustra DVD entitled “Darwin’s Dilemma”.  But that will have to be the subject of someone else’s writing, since I didn’t go to the screening, nor did I bother to scarf up a DVD.)

It was probably against my better judgment to do this, but I folded this event in with some other, more professorial activities and managed to have a productive and agreeable visit to Biola.

But this blog entry is about the Signature in the Cell event.  The format for this was a bit different from your usual debate – thus, after the glitzy Meyer presentation, a panel of hand-selected critics (chosen by the event organizers) would be given opportunities to grill Meyer.  In other words, there would be no tit-for-tat here, but rather a one-way exchange of Q&A.  This is roughly what transpired, but in a shorter period of time than I expected.

What follows is a recap (from memory – I didn’t bother trying to scribble down notes while everyone was talking) of the proceedings.  This is intended as much as anything to convey my own impressions, and should not be mistaken for advice or instructions on how to approach things like this.

It’s getting crowded

One of the interesting things about the polyadenylation complex is the multiplicity of RNA-binding proteins in the system.  As I mentioned before, there are many such proteins, more than the numbers of cis elements typically associated with polyadenylation.  Closer inspection of the complex reveals more paradoxes involved RNA-binding proteins and polyadenylation.

Recently, a rotation student in my lab published a study that reported the discovery of a new RNA-binding domain in the plant polyadenylation complex (1).  There are two findings that are described this study.  The obvious one, that can be extracted from the title, is that the 77 kD subunit of the Arabidopsis Cleavage Stimulatory Complex (CstF77) is in fact an RNA binding protein.  In this report, the new RNA-binding domain was localized to the C-terminus of the protein.  This is interesting because this part of CstF77 is not conserved in its eukaryotic (yeast and mammalian) counterparts.  This raises the possibility that RNA binding by CstF77 is a plant-specific phenomenon.

The second interesting finding is the location of the RNA-binding domain. The structures of two eukaryotic CstF77 proteins have been solved, and  it has been established that the protein exists as a dimer (2,3).  The dimer is “held together” by extensive interactions involving the “middle” of the protein, and several of the characteristic “HAT” motifs (4) in the protein.  The C-termini of each subunit of the dimer probably extends into the cavity formed by the dimer, as suggested in the figure below.