Release of ubiquitin-charged Cdc34-S~Ub from the RING domain is essential for ubiquitination of the SCF
Andrew E Deffenbaugh, K. Matthew Scaglione, Lingxiao Zhang, Johnnie M. Moore, Tione Buranda, Larry A. Sklar, and Dorota Skowyra.
Cell. 114(5):611-622, 2003. (PMID 13678584)
The mechanism of polyubiquitination was initially thought to involve stable interaction between the E2, the E3 and a substrate. Our "hit and run" hypothesis (Figure below) published in Deffenbaugh et al. was the first to propose that, in contrast to stability of the E3-substrate interaction, the process of polyubiquitination involves repeated cycles of interaction between the E2 and the E3. In the same study, we also provided evidence suggesting that a release of ubiquitin-charged Cdc34 E2 from its primary recruitment site on the RING domain of SCF
The "Hit and Run" model for Cdc34 function with SCF
ATP hydrolysis-dependent disassembly of the 26S proteasome is part of the catalytic cycle.
Shalon E. Babbitt, Alexi Kiss, Andrew E. Deffenbaugh, Yie-Hwa Chang, Eric Bailly, Hediye Erdjument-Bromage, Paul Tempst, Tione Buranda, Larry A. Sklar, Jennifer Baumler, Edward Gogol, and Dorota Skowyra.
Cell. 121(4):553-565, 2005 (PMID 15907469)
Using the yeast 26S proteasomes co-purified with proteasome-interacting proteins (PIPs), such as polyubiquitinated substrates and the SCF E3 ubiquitin ligase complexes, we showed that the end of substrate proteolysis is linked to an ATP hydrolysis-dependent dissociation and disassembly of the 19S activator, and that this step co-incides with a burst-like release of product peptides. Based on these findings, we proposed the "chew and spew" model for coupling ATP hydrolysis with diassembly of the 26S proteasome (Figure below). This study was the first demonstration that disassembly of the 26S proteasome could be linked to the catalytic cycle.
The "Chew and Spew" model for coupling ATP hydrolysis to disassembly of the 26S proteasome.
Destabilization of binding to cofactors and SCF
Srikripa Chandrasekaran, Andrew E. Deffenbaugh, David A. Ford, Eric Bailly, Neal Mathias, and Dorota Skowyra.
Mol. Cell. 24(5):689-699, 2006. (PMID 17157252)
In Chandrasekaran et al., we reported a novel regulatory mechanism in which a substrate polyubiquitinated with the cannonical K48-type of polyubiquitin chain can collaborate with other proteins to temporarily stall its own degradation until receiving a further regulatory signal, This paradigm was established by reconstruction of the SCF
Roadmap highlighting the relationship between the SCF