Characterization of processing and stress granules under differential heat stress stringency in yeast.

MARCOVICH IRINA; BARRAZA CARLA; MORENO SILVIA; PORTELA PAULA

CABA

Congreso; Reunion 2013 SAIB : Molecular Mechanisms in cell signaling and gene expression; 2013

SAIB

We have previously shown that Tpk2 and Tpk3 subunit isoforms of PKA differentially localize to processing bodies (PBs) and stress granules (SGs) evoked by severe and middle heat stress. Here, we investigate in more detail the mechanisms and signaling pathways involved in PBs/SGs granule formation induced by stress severity. Severe heat stress triggers formation of PBs and SGs containing Tpk2 and Tpk3 subunits and leads to the accumulation and aggregation of 48S pre-initiation complex. The aggregation of Tpk does not require sphingolipid signaling. On the contrary, middle heat stress triggers Tpk3 foci formation as well as Tpk3 accumulation on PBs and SGs granules, in a process depending on sphingolipid synthesis. This stress promotes the accumulation and aggregation up to the close loop mRNA complex. To globally characterize the proteins associated to the granules evoked by middle and severe heat stress we identified the protein composition of granular fractions enriched by sedimentation combined with 2D electrophoresis and MALDI MS-MS. We identified proteins exclusively enriched at middle heat stress, proteins exclusively enriched at severe heat stress as well as proteins common to both groups. These results suggest that different degrees of severity of the same stress evoke specific responses on RNP assembly