Today, our lab has published a comprehensive review on the PIN domain, which is a ubiquitous protein domain found in all domains of life. Our analysis demonstrates that we are far from knowing everything we need to know about PIN domains, which in many cases (but not always) function as small RNA nucleases.
Firstly, there is still no structure of a PIN domain bound to its RNA target, which leaves open question both as to how RNA is specifically bound as well as how cleavage occurs. The active site, which consists of a number of acidic side chains, is conserved in many cases, but the details of catalysis are far from understood. Even more intriguingly, some PIN domains (such as those found among bacterial VapC toxins) appear to cleave very specific RNA species including tRNA and ribosomal RNA. Our review also highlights the need to understand how this specificity arises.
For more information, see the paper in Protein Science.
Senissar, M., Manav, M. C., Brodersen, D. E. (2017) “Structural conservation of the PIN domain active site across all domains of life”, Protein Sci, 26(8):1474-1492.