One of the reasons for the slow pace of entries here has been the intrusion of, um, life into my life. (Yeah, figure that one out.) Earlier this summer, a paper from my lab was published in BMC Cell Biology. Seeing as it’s Open Access, and since it has a bit of relevance to a theme introduced in this essay, I thought I would point it out here.
The story in a nutshell – one of the subunits of the polyadenylation complex is the so-called CPSF30 protein, or its yeast relative Yth1. (Yth1 looms large as one of the few subunits in the Giardia complex.) What Drs. Suryadevara Rao and Randy Dinkins did was study the places within the cell where CPSF30 goes, and what happens when one co-expresses this protein with other polyadenylation complex subunits. They did this by attaching the various proteins to fluorescent proteins and following the fusion proteins using microscopic techniques.
The results corroborated other studies that detailed interactions between various of these proteins. However, a rudimentary deletion analysis showed that these interactions by and large involve parts of CPSF30 that are not found in the mammalian or yeast proteins. Since the CPSF30 interacts with the other proteins of interest in this study (the 160, 100, and 73 kD subunits of the cleavage and polyadenylation specificity factor, or CPSF) in other eukaryotes, it stands to reason that the interactions themselves must have evolved independently. This in turn suggests a somewhat different trajectory in the evolution of the complex in different eukaryotic lineages. It also raises the possibility that the different complexes may process and polyadenylate RNAs in subtly different ways.
Some pretty pictures and a link to a fascinating movie may be found beneath the fold. Enjoy. Read the rest of this entry »