A novel step in beta-tubulin folding is important for heterodimer formation in Saccharomyces cerevisiae.
Undimerized beta-tubulin is toxic in the yeast S. cerevisiae. It can arise if levels of beta-tubulin and alpha-tubulin are unbalanced or if the tubulin heterodimer dissociates. We are using the toxicity of beta-tubulin to understand early steps in microtubule morphogenesis. We find that deletion of PLP1 suppresses toxic beta-tubulin formed by disparate levels of alpha- and beta-tubulin. That suppression occurs either when alpha-tubulin is modestly underexpressed relative to beta-tubulin or when beta-tubulin is inducibly and strongly overexpressed. Plp1p does not affect tubulin expression. Instead, a significant proportion of the undimerized beta-tubulin in plp1Delta cells is less toxic than that in wild-type cells. It is also less able to combine with alpha-tubulin to form a heterodimer. As a result, plp1Delta cells have lower levels of heterodimer. Importantly, plp1Delta cells that also lack Pac10, a component of the GimC/PFD complex, are even less affected by free beta-tubulin. Our results suggest that Plp1p defines a novel early step in beta-tubulin folding.
Department of Biology and Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Soni
S
Lacefield
Frank
F
Solomon
D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D018834:Chaperonin 60 / Q000378:metabolism; D019281:Dimerization; D044783:F-Box Proteins; D017353:Gene Deletion; D008074:Lipoproteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D017510:Protein Folding; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D014404:Tubulin / Q000235:genetics / Q000378:metabolism* / Q000633:toxicity; D044767:Ubiquitin-Protein Ligases
D002352:Carrier Proteins; D018834:Chaperonin 60; D044783:F-Box Proteins; D008074:Lipoproteins; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; C443671:RBL2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C475499:Tub3 protein, S cerevisiae; D014404:Tubulin; C071032:GRR1 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases