The proteasome is responsible for most intracellular protein degradation and is essential for cell survival. Previous research has shown that the proteasome can be inhibited by a number of oxidants, including 4-hydroxynonenal (HNE). The present study demonstrates that HNE rapidly inhibits the chymotrypsin-like activity of the 20S proteasome purified from liver. Subunits containing HNE-adducts were identified following 2D gel electrophoresis, Western immunoblotting, and analysis by MALDI-TOF MS. At a time when only the chymotrypsin-like activity was inhibited, the α6/C2 subunit was uniquely modified. These results provide important molecular details regarding the catalytic site-specific inhibition of proteasome by HNE.
Bibliographical noteFunding Information:
We thank Tina Tran and Gina Knade for their technical assistance. This work was supported by the National Institutes of Health -National Eye Institute (EY013623), Foundation Fighting Blindness, American Federation for Aging Research, Minnesota Medical Foundation, Grant-In-Aid from the Graduate School of the University of Minnesota and an unrestricted grant to the Department of Ophthalmology from Research to Prevent Blindness Foundation. We acknowledge the Mass Spectrometry Consortium for the Life Sciences, University of Minnesota, St. Paul, MN, for the assistance in acquisition of mass spectral data.
- 20S proteasome
- Chymotrypsin-like activity
- MALDI-TOF mass spectrometry
- Proteasome inhibition