Similar but Not the Same, the Fission Yeast Processing Bodies

Cytoplasmic processing bodies (P-bodies) are RNA protein granules containing un translating mRNAs complexes with a set of translation repressors, the mRNA decapping machinery Dcp1-Dcp2 and the 5’-3’ exonuclease Xrn1 where mRNA decay can occur and have merged as important sub cellular structures that are involved in mRNA metabolism. Although components of P-bodies have been described in Schizosaccharomyces pombe, a detailed description of P-bodies is still lacking. To this end, we have initiated a study to characterize the fission yeast P-bodies and several interesting aspects with regard to the protein composition between different species and underlying molecular mechanisms for their function were identified (Figure 1) [1,2]. Because of its importance, several model systems have been applied to study the structure of P-bodies, and studies in the budding yeast Saccharomyces cerevisiae have been crucial in unravelling P-body biology. However, there is a clear difference in terms of the decapping proteins presence in different organisms. In yeast, the catalytic subunit of decapping enzyme Dcp2 interacts directly with its cofactor Dcp1 [3]. This complex has low intrinsic decapping activity and requires additional proteins including the enhancer of decapping 1-3 (Edc1-3), the heptametrical Lsm1-7 complex, the DExH/D-box RNA heli case 1 (Dhh1, RCK/p54 in mammals) and Pat1 for its full activity. All of these proteins concentrate in P-bodies and function differentially in activating decapping [4].