Attack from both ends: mRNA degradation in the crenarchaeon Sulfolobus solfataricus.

RNA stability control and degradation are employed by cells to control gene expression and to adjust the level of protein synthesis in response to physiological needs. In all domains of life, mRNA decay can commence in the 5'-3' as well as in the 3'-5'-direction. Consequently, mechanisms are in place conferring protection on mRNAs at both ends. Upon deprotection, dedicated enzymes/enzyme complexes access either end and trigger 5'-3' or 3'-5'-directional decay. In the present paper, we first briefly review the general mRNA decay pathways in Bacteria and Eukarya, and then focus on 5'-3' and 3'-5'-directional decay in the crenarchaeon Sulfolobus solfataricus, which is executed by a RNase J-like ribonuclease and the exosome complex respectively. In addition, we describe mechanisms that stabilize mRNAs at the 5'- as well as at the 3'-end.