The eukaryote chaperonin CCT is a cold shock protein in Saccharomyces cerevisiae

Abstract

The eukaryotic Hsp60 cytoplasmic chaperonin CCT (chaperonin containing the T-complex polypeptide-1) is essential for growth in budding yeast, and mutations in individual CCT subunits have been shown to affect assembly of tubulin and actin. The present research focused mainly on the expression of the CCT subunits, CCTalpha and CCTbeta, in yeast (Saccharomyces cerevisiae). Previous studies showed that, unlike most other chaperones, CCT in yeast does not undergo induction following heat shock. In this study, messenger ribonucleic acid (mRNA) and protein levels of CCT subunits following exposure to low temperatures, were examined. The Northern blot analysis indicated a 3- to 4-fold increase in mRNA levels of CCTalpha and CCTbeta genes after cold shock at 4 degrees C. Interestingly, Western blot analysis showed that cold shock induces an increase in the CCTalpha protein, which is expressed at 10 degrees C, but not at 4 degrees C. Transfer of 4 degrees C cold-shocked cells to 10 degrees C induced a 5-fold increase in the CCTalpha protein level. By means of fluorescent immunostaining and confocal microscopy, we found CCTalpha to be localized in the cortex and the cell cytoplasm of S. cerevisiae. Localization of CCTalpha was not affected at low temperatures. Co-localization of CCT and filaments of actin and tubulin was not observed by microscopy. The induction pattern of the CCTalpha protein suggests that expression of the chaperonin may be primarily important during the recovery from low temperatures and the transition to growth at higher temperatures, as found for other Hsps during the recovery phase from heat shock.

Biology of the Heat Shock Response and Protein Chaperones: Budding Yeast (Saccharomyces cerevisiae) as a Model System

“…It was initially thought that these proteins are not stress induced based on results examining transcript levels after heat shock (38°C), but at least one CCT transcript accumulates after cold shock. Additionally, CCT protein levels increase when cells are shifted from 4°C to 10°C, suggesting that CCT may be involved in cold shock recovery (433). This notion is also supported by a suppressor screen that found that the overexpression of ribosomal proteins suppresses CCT defects (217).…”

Up-regulation of heat shock proteins is essential for cold survival during insect diapause

“…Several direct links have been made between TCP-1 and cold survival. In yeast, TCP-1 is upregulated by cold shock (52), and a cold-sensitive mutant was reported to result from mutation of TCP-1 (53). More recently, the up-regulation of TCP-1 has been associated with cold hardiness in the onion maggot, D. antiqua (54), and has also been implicated in diapause of the brine shrimp, A. franciscana, where it is found in association with microtubules in undeveloped cysts (55).…”

Expression of mRNA for the t-complex polypeptide–1, a subunit of chaperonin CCT, is upregulated in association with increased cold hardiness in Delia antiqua

“…In contrast, CCT, a chaperonin in group II, was considered not to be induced by stress until the early 1990s (Ursic and Culbertson 1992;Leroux and Candido 1995). Recently, however, CCT was shown to be induced by heat shock in human cells (Schena et al 1996), chemical stress (CdCl 2 ) in Oxytricha granulifera (Palmedo and Ammermann 1997), and cold shock in the yeast Saccharomyces cerevisiae (Somer et al 2002).…”

“…As mentioned in the Introduction, actin and tubulin are the major substrates of CCT. On the basis of the finding that CCT was upregulated in response to low temperature in the yeast S cerevisiae, Somer et al (2002) hypothesized that upregulation of CCT expression is related to the reorganization of actin and tubulin monomers during the recovery from cold stress. In view of these findings, the upregulation of DaTCP-1 expression in D antiqua is likely to be related to the recrystallization or rearrangement of actin and tubulin and hence contribute to the reinforcement of cold hardiness.…”