@article{FischerHarrisonRamirezetal.2017,
  author    = {Fischer, Annette and Harrison, Kelly S and Ramirez, Yesid and Auer, Daniela and Chowdhury, Suvagata Roy and Prusty, Bhupesh K and Sauer, Florian and Dimond, Zoe and Kisker, Caroline and Hefty, P Scott and Rudel, Thomas},
  title     = {Chlamydia trachomatis-containing vacuole serves as deubiquitination platform to stabilize Mcl-1 and to interfere with host defense},
  series = {eLife},
  volume    = {6},
  journal   = {eLife},
  number    = {e21465},
  doi       = {10.7554/eLife.21465},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-171073},
  year      = {2017},
  abstract  = {Obligate intracellular Chlamydia trachomatis replicate in a membrane-bound vacuole called inclusion, which serves as a signaling interface with the host cell. Here, we show that the chlamydial deubiquitinating enzyme (Cdu) 1 localizes in the inclusion membrane and faces the cytosol with the active deubiquitinating enzyme domain. The structure of this domain revealed high similarity to mammalian deubiquitinases with a unique α-helix close to the substrate-binding pocket. We identified the apoptosis regulator Mcl-1 as a target that interacts with Cdu1 and is stabilized by deubiquitination at the chlamydial inclusion. A chlamydial transposon insertion mutant in the Cdu1-encoding gene exhibited increased Mcl-1 and inclusion ubiquitination and reduced Mcl-1 stabilization. Additionally, inactivation of Cdu1 led to increased sensitivity of C. trachomatis for IFNγ and impaired infection in mice. Thus, the chlamydial inclusion serves as an enriched site for a deubiquitinating activity exerting a function in selective stabilization of host proteins and protection from host defense.},
  language  = {en}
}
@phdthesis{Klemm2020,
  author    = {Klemm, Theresa Antonia},
  title     = {Minor differences cause major effects: How differential oligomerization regulates the activities of USP25 and USP28},
  doi       = {10.25972/OPUS-19108},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-191080},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2020},
  abstract  = {Deubiquitinases are regulators of the ubiquitin proteasome system that counteract the ubiquitination cascade by removing ubiquitin from substrates and cleaving ubiquitin chains. Due to their involvment in various important pathways, they are associated with several diseases and may thus present promising drug targets. The two related ubiquitin specific proteases USP25 and USP28 share a highly conserved amino acid sequence but perform distinct biological functions. USP28 plays roles in cell cycle regulation and was also linked to several types of cancer. It adopts oncogenic functions by rescuing the oncoproteins MYC and JUN from proteasomal degradation, which is induced by the E3-ligase SCF (FBW7). Opposingly, USP28 also regulates the stability of the tumor suppressor FBW7 itself. USP25 contributes to a balanced innate immune system by stabilizing TRAF3 and TRAF6 and lately was found to promote Wnt-signaling by deubiquitinating TNKS. Due to the high level of identity of both proteases, a recent attempt to inhibit USP28 led to cross reactivity against USP25. In our study, we characterized both USP25 and USP28 structurally and functionally using x-ray crystallography, biochemical as well as biophysical approaches to determine similarities and differences that can be exploited for the development of specific inhibitors. The crystal structure of the USP28 catalytic domain revealed a cherry-couple like dimer that mediates self-association by an inserted helical subdomain, the USP25/28 catalytic domain inserted domain (UCID). In USP25, the UCID leads to formation of a tetramer composed of two interlinked USP28-like dimers. Structural and functional analysis revealed that the dimeric USP28 is active, whereas the tetrameric USP25 is auto inhibited. Disruption of the tetramer by a cancer-associated mutation or a deletion-variant activates USP25 through dimer formation in in vitro assays and leads to an increased stability of TNKS in cell studies. Furthermore, in vitro data showed that neither ubiquitin nor substrate binding led to the activation of the USP25 tetramer construct. With the structure of the C-terminal domain of USP25, we determined the last unknown region in the enzyme as a separately folded domain that mediates substrate interactions. Combined the structures of the USP25 and USP28 catalytic domains and the functional characterization of both enzymes provide novel insights into the regulation of USPs by oligomerization. Furthermore, we identified individual features of each protease that might be explored for the development of specific small molecule inhibitors.},
  subject      = {Oligomerisation},
  language  = {en}
}