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| Author(s): |
Letícia Veloso Ribeiro Franco
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Escola Politécnica (EP/BC) |
| Defense date: | 2016-12-19 |
| Examining board members: |
Andreas Karoly Gombert;
Adriano Rodrigues Azzoni;
Rosana Goldbeck;
José Gregorio Cabrera Gomez;
Erich Birelli Tahara
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| Advisor: | Andreas Karoly Gombert; Mário Henrique de Barros |
| Abstract | |
The initial goal of this work was to overexpress proteins with ATPase activity in Saccharomyces cerevisiae, as an attempt to alter the conservation of free energy in this yeast, in order to increase alcoholic fermentation yield. Therefore, two native S. cerevisiae ATPases, the chaperones encoded by HSP104 and CDC48, were individually overexpressed under the control of four promoters with different strengths, in order to provoke different levels of energy expenditure. Increments in the ethanol yield could not be observed in any of the constructed strains. Subsequently, a study was carried out to compare these mutant strains with reference strains under heat, acid or osmotic stress, which are typically found in the industrial fuel ethanol production in Brazil. At 40 oC a strain overexpressing CDC48 displayed a maximum specific growth rate 17 % higher than that of the reference strain, indicating a greater tolerance to heat stress. Finally, Hsp104 and Cdc48 were evaluated in a physiological context in which the activity of these proteins would be required in a higher level. Since molecular chaperones are known to act as the first defense line against the formation of misfolded proteins and aggregates, the physiological and morphological effects of HSP104 or CDC48 overexpression were analyzed in strains with protein quality control disarrangements caused by mutations in proteasome 20S. The overexpression of either CDC48 or HSP104 partially reversed the altered morphology of some of these proteasome mutants. (AU) | |
| FAPESP's process: | 13/26238-3 - Substitution of the glycolytic pathway in Saccharomyces cerevisiae to increase the conversion of sugar into ethanol |
| Grantee: | Leticia Veloso Ribeiro Franco |
| Support Opportunities: | Scholarships in Brazil - Doctorate (Direct) |