XRN1 story

Xrn1 is an evolutionarily conserved exoribonuclease and the major mRNA degradation enzyme of S. cerevisiae. Besides its localization through the yeast cell, Xrn1 is gradually being sequestrated into P-bodies as the yeast population ages. P-bodies are RNA granules that were considered to be sites of the degradation of mRNA molecules. However, recent studies have challenged this hypothesis.

We found that Xrn1 is also located in the MCC/eisosome compartment at the yeast plasma membrane. This localization correlates with the metabolic (diauxic) switch from glucose fermentation to respiration. This unique localization pattern of Xrn1 can serve as an intrinsic marker of yeast population growth. At the same time, Xrn1 localization outside of P-bodies in the post-diauxic growth phase supports a rather cytoprotective yet still not completely elucidated function of P-bodies in cellular metabolism.