Abstract
The ubiquitin-selective chaperone Cdc48, a member of the AAA (ATPase Associated with various cellular Activities) ATPase superfamily, is involved in many processes, including endoplasmic reticulum-associated degradation (ERAD), ubiquitin- and proteasome-mediated protein degradation, and mitosis. Although Cdc48 was originally isolated as a cell cycle mutant in the budding yeast Saccharomyces cerevisiae, its cell cycle functions have not been well appreciated. We found that temperature-sensitive cdc48-3 mutant is largely arrested at mitosis at 37°C, whereas the mutant is also delayed in G1 progression at 38.5°C. Reporter assays show that the promoter activity of G1 cyclin CLN1, but not CLN2, is reduced in cdc48-3 at 38.5°C. The cofactor npl4-1 and ufd1-2 mutants also exhibit G1 delay and reduced CLN1 promoter activity at 38.5°C, suggesting that Npl4-Ufd1 complex mediates the function of Cdc48 at G1. The G1 delay of cdc48-3 at 38.5°C is a consequence of cell wall defect that over-activates Mpk1, a MAPK family member important for cell wall integrity in response to stress conditions including heat shock. cdc48-3 is hypersensitive to cell wall perturbing agents and is synthetic-sick with mutations in the cell wall integrity signaling pathway. Our results suggest that the cell wall defect in cdc48-3 is exacerbated by heat shock, which sustains Mpk1 activity to block G1 progression. Thus, Cdc48-Npl4-Ufd1 is important for the maintenance of cell wall integrity in order for normal cell growth and division.
Highlights
Budding yeast Cdc48 and its metazoan homolog p97, named as valosin-containing protein (VCP), are abundant and evolutionarily conserved proteins
G1 delay of cdc48-3 at high temperature In order to understand the cell cycle function of Cdc48, we have examined the phenotypes of the temperature-sensitive cdc48-3 mutant
We report that mutations in Cdc48 and its cofactors Npl4 and Ufd1 prolong the G1 delay in the budding yeast Saccharomyces cerevisiae at 38.5uC
Summary
Budding yeast Cdc and its metazoan homolog p97, named as valosin-containing protein (VCP), are abundant and evolutionarily conserved proteins. Cdc48/p97 belongs to the AAA ATPase superfamily and is involved in many aspects of cellular activities, including homotypic membrane fusion of organelles [1], ERAD [2], ubiquitin/proteasome-mediated protein degradation [3], and cell cycle control [4]. Npl contains NZF domain that binds polyubiquitin chain [6]. Cdc coupled with Npl4Ufd functions in retrograde translocation of proteins from ER for degradation (ERAD) [8]. Cdc48/p97 binds a family of proteins containing a ubiquitin-related (UBX) domain that is structurally similar to ubiquitin [9]. Known as Shp (Suppressor of high copy protein phosphatase 1) [10], Ubx, Ubx, Ubx, and Ubx serve as cofactors for Cdc in ubiquitindependent protein degradation [11]. The mammalian homolog of Shp, p47, is involved in membrane fusion [13]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
