Journal
JOURNAL OF MOLECULAR BIOLOGY
Volume 395, Issue 3, Pages 587-594Publisher
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmb.2009.11.017
Keywords
ubiquitin; protein turnover; tandem mass spectrometry; molecular chaperone; C-terminus of Hsc70 interacting protein
Categories
Funding
- NIGMS NIH HHS [T32 GM008283-19, T32 GM008283] Funding Source: Medline
Ask authors/readers for more resources
Molecular chaperones Hsp70 and Hsp90 are in part responsible for maintaining the viability of cells by facilitating the folding and maturation process of many essential client proteins. The ubiquitin ligase C-terminus of Hsc70 interacting protein (CHIP) has been shown in vitro and in vivo to associate with Hsp70 and Hsp90 and ubiquitinate them, thus targeting them to the proteasome for degradation. Here, we study one facet of this CHIP-mediated turnover by determining the lysine residues on human Hsp70 and Hsp90 ubiquitinated by CHIP. We performed in vitro ubiquitination reactions of the chaperones using purified components and analyzed the samples by tandem mass spectrometry to identify modified lysine residues. Six such ubiquitination sites were identified on Hsp70 (K325, K451, K524, K526, K559, and K561) and 13 ubiquitinated lysine residues were found on Hsp90 (K107, K204, K219, K275, K284, K347, K399, K477, K481, K538, K550, K607, and K623). We mapped the ubiquitination sites on homology models of almost full-length human Hsp70 and Hsp90, which were found to cluster in certain regions of the structures. Furthermore, we determined that CHIP forms polyubiquitin chains on Hsp70 and Hsp90 linked via K6, K11, K48, and K63. These findings clarify the mode of ubiquitination of Hsp70 and Hsp90 by CHIP, which ultimately leads to their degradation. (C) 2009 Elsevier Ltd. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available