Can the different heat shock response thresholds found in fermenting and respiring yeast cells be attributed to their differential redox states?

Yeast ◽  
2007 ◽  
Vol 24 (8) ◽  
pp. 653-666 ◽  
Author(s):  
Christos Moraitis ◽  
Brendan P. G. Curran
1991 ◽  
Vol 11 (2) ◽  
pp. 1062-1068
Author(s):  
H J Yost ◽  
S Lindquist

In the yeast Saccharomyces cerevisiae, the splicing of mRNA precursors is disrupted by a severe heat shock. Mild heat treatments prior to severe heat shock protect splicing from disruption, as was previously reported for Drosophila melanogaster. In contrast to D. melanogaster, protein synthesis during the pretreatment is not required to protect splicing in yeast cells. However, protein synthesis is required for the rapid recovery of splicing once it has been disrupted by a sudden severe heat shock. Mutations in two classes of yeast hsp genes affect the pattern of RNA splicing during the heat shock response. First, certain hsp70 mutants, which overproduce other heat shock proteins at normal temperatures, show constitutive protection of splicing at high temperatures and do not require pretreatment. Second, in hsp104 mutants, the recovery of RNA splicing after a severe heat shock is delayed compared with wild-type cells. These results indicate a greater degree of specialization in the protective functions of hsps than has previously been suspected. Some of the proteins (e.g., members of the hsp70 and hsp82 gene families) help to maintain normal cellular processes at higher temperatures. The particular function of hsp104, at least in splicing, is to facilitate recovery of the process once it has been disrupted.


1991 ◽  
Vol 11 (2) ◽  
pp. 1062-1068 ◽  
Author(s):  
H J Yost ◽  
S Lindquist

In the yeast Saccharomyces cerevisiae, the splicing of mRNA precursors is disrupted by a severe heat shock. Mild heat treatments prior to severe heat shock protect splicing from disruption, as was previously reported for Drosophila melanogaster. In contrast to D. melanogaster, protein synthesis during the pretreatment is not required to protect splicing in yeast cells. However, protein synthesis is required for the rapid recovery of splicing once it has been disrupted by a sudden severe heat shock. Mutations in two classes of yeast hsp genes affect the pattern of RNA splicing during the heat shock response. First, certain hsp70 mutants, which overproduce other heat shock proteins at normal temperatures, show constitutive protection of splicing at high temperatures and do not require pretreatment. Second, in hsp104 mutants, the recovery of RNA splicing after a severe heat shock is delayed compared with wild-type cells. These results indicate a greater degree of specialization in the protective functions of hsps than has previously been suspected. Some of the proteins (e.g., members of the hsp70 and hsp82 gene families) help to maintain normal cellular processes at higher temperatures. The particular function of hsp104, at least in splicing, is to facilitate recovery of the process once it has been disrupted.


2014 ◽  
Vol 13 (8) ◽  
pp. 1077-1084 ◽  
Author(s):  
Michelle D. Leach ◽  
Leah E. Cowen

ABSTRACTTemperature is a ubiquitous environmental variable which can profoundly influence the physiology of living cells as it changes over time and space. When yeast cells are exposed to a sublethal heat shock, normal metabolic functions become repressed and the heat shock transcription factor Hsf1 is activated, inducing heat shock proteins (HSPs).Candida albicans, the most prevalent human fungal pathogen, is an opportunistic pathogen that has evolved as a relatively harmless commensal of healthy individuals. Even thoughC. albicansoccupies thermally buffered niches, it has retained the classic heat shock response, activating Hsf1 during slow thermal transitions such as the increases in temperature suffered by febrile patients. However, the mechanism of temperature sensing in fungal pathogens remains enigmatic. A few studies withSaccharomyces cerevisiaesuggest that thermal stress is transduced into a cellular signal at the level of the membrane. In this study, we manipulated the fluidity ofC. albicansmembrane to dissect mechanisms of temperature sensing. We determined that in response to elevated temperature, levels ofOLE1, encoding a fatty acid desaturase, decrease. Subsequently, loss ofOLE1triggers expression ofFAS2, encoding a fatty acid synthase. Furthermore, depletion ofOLE1prevents full activation of Hsf1, thereby reducingHSPexpression in response to heat shock. This reduction in Hsf1 activation is attributable to the E3 ubiquitin ligase Rsp5, which regulatesOLE1expression. To our knowledge, this is the first study to define a molecular link between fatty acid synthesis and the heat shock response in the fungal kingdom.


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