[BK21 Plus Seminar]
                 
                   
                ▶Subject: Regulation of Proteasome Activity by Ubiquitin Chain Editing
                           
                ▶Speaker: Byung-Hoon Lee, PH.D.
                    (Department of Cell Biology, Harvard Medical School)
                                        
                ▶Date: 2:00PM/Oct. 26(Mon.)/2015
                        
                ▶Place: Life Science Bldg. #104
                         
                       *Abctract
                  The 26S proteasome is increasingly recognized as a versatile player for fine-tuning the substrate degradation. However, ubiquitin conjugate processing by the mammalian proteasome still remains poorly understood, partly due to the lack of specific tools. We recently developed a potent small-molecule inhibitor selectively targeting USP14, a major deubiquitinating enzyme on the proteasome. By employing this inhibitor along with mass spectrometry, we discovered that ubiquitin chain processing on the proteasome is surprisingly sophisticated, discriminating very sensitively among substrates on the basis of diverse configurations of the ubiquitin conjugates. Single-molecule and quench-flow studies also revealed that the suppression of degradation by USP14’s catalytic activity reflects its capacity to act on a millisecond time scale, before the proteasome can initiate degradation of the substrate. Our data suggest a dynamic engagement of USP14 in recognizing and processing the chain in the context of proteasome.

             ▶Inquiry: Prof. Hwang, Cheol-Sang (279-2352)
                       
                * This seminar will be given in English.
        please refrain from taking photos during seminars. *