Material
Abstract
The yeast Hsp70/40 system SSB-RAC (stress 70 B-ribosome-associated complex) binds to ribosomes and contacts nascent polypeptides to assist cotranslational folding. In this study, we demonstrate that nascent polypeptide-associated complex (NAC), another ribosome-tethered system, is functionally connected to SSB-RAC and the cytosolic Hsp70 network. Simultaneous deletions of genes encoding NAC and SSB caused conditional loss of cell viability under protein-folding stress conditions. Furthermore, NAC mutations revealed genetic interaction with a deletion of Sse1, a nucleotide exchange factor regulating the cytosolic Hsp70 network. Cells lacking SSB or Sse1 showed protein aggregation, which is enhanced by additional loss of NAC; however, these mutants differ in their potential client repertoire. Aggregation of ribosomal proteins and biogenesis factors accompanied by a pronounced deficiency in ribosomal particles and translating ribosomes only occurs in ssbDelta and nacDeltassbDelta cells, suggesting that SSB and NAC control ribosome biogenesis. Thus, SSB-RAC and NAC assist protein folding and likewise have important functions for regulation of ribosome levels. These findings emphasize the concept that ribosome production is coordinated with the protein-folding capacity of ribosome-associated chaperones.
BibTeX
@article{Koplin2010dualfunctionchaperones,
author = {A. Koplin and S. Preissler and Y. Ilina and M. Koch and A. Scior and M. Erhardt and E. Deuerling},
doi = {10.1083/jcb.200910074},
eprint = {http://jcb.rupress.org/content/189/1/57.full.pdf},
issn = {0021-9525},
journal = {The Journal of Cell Biology},
number = {1},
pages = {57--68},
publisher = {Rockefeller University Press},
title = {A dual function for chaperones SSBtextendashRAC and the NAC nascent polypeptidetextendashassociated complex on ribosomes},
url = {http://jcb.rupress.org/content/189/1/57},
volume = {189},
year = {2010},
}