Chapter 7 5 0 - 3 0 Exoribonucleases Jeong

The 50-30 exoribonucleases have important functions in RNA processing, RNA degradation, RNA interference, transcription, and other cellular processes. The Xrn1 and Xrn2/Rat1 family of enzymes are the best characterized 50-30 exoribonucleases, and there has been significant recent progress in the understanding of their structure and function. Especially, the first structural information on Rat1 just became available. Other 50-30 exoribonucleases have been identified recently, including yeast Rrp17 and B. subtilis RNase J1, the first enzyme with 50-30 exoribonuclease activity found in prokaryotes. This review will summarize our current understanding of these enzymes, focusing on their sequence conservation, molecular structure, biochemical and cellular functions.