PERSONAL DE APOYO
FERNÁNDEZ Jorge GermÁn
congresos y reuniones científicas
Título:
Proteome wide analysis of granular protein complexes evoked by differential heat stress stringency in Saccharomyces cerevisiae
Autor/es:
SILVIA MORENO DE COLONNA; CARLA BARRAZA; MARIA PIA VALACCO; JORGE GERMÁN FERNÁNDEZ; PAULA PORTELA
Lugar:
Postdam
Reunión:
Congreso; Proteomic Forum 2017; 2017
Resumen:
Cellular responses to stress comprise a variety of different mechanisms, including translation arrest and relocation of the translationally repressed mRNAs to ribonucleic particles (mRNPs) such as stress granules (SGs) and processing bodies (PBs). Given recent evidence on the role of liquid phase transition in signalling and cytosolic mRNPs formation, it is possible that SGs might represent regions where certain processes or the activity of enzymes are concentrated. Our results from biochemical and microscopy approaches show that under mild heat stress the catalytic subunit of PKA isoform Tpk3 aggregates and promotes transfer of closed mRNA loop complexes into SGs, whereas severe heat stress leads to the formation of PBs and SGs that also contain the Tpk2 isoform and a larger 48S translation initiation complex (1,2 and unpublished). PKA affects the translational response to heat stress, where each Tpk catalytic isoform appears to have a different role, with Tpk2 and Tpk3 playing negative and positive roles in the translational response, respectively. We favour a model where depending on the severity of an external stimulus, such as heat stress, each catalytic isoform of PKA interacts with a complex network of distinct protein factors and potential substrates.Our ongoing studies are focused on a global characterization of protein complexes under different heat stress conditions. To this end, we performed a proteomic analysis of the granular enriched fraction from mild and severe heat stress by two approaches: I) Differential 2D gel electrophoresis and mass spectrometry identification by MALDI-TOF-TOF and II) Label-free quantitative proteomics using a QExactive. We identified proteins differentially enriched in middle and severe heat stress, as well as proteins common to both groups. Gene ontology analysis of the enriched proteins showed annotations associated with several GO biological processes, such as structural constituent of ribosome, RNA binding, translation factor activity, ATPase activity and unfolded protein binding. Networks built from these results will let us start defining how different degrees of severity of the same stress evoke a specific response on RNP assembly.