ZMB Member Michael Ehrmann
Mechanism and Translational Aspects of Protein Quality Control
Each cell hosts thousands of different proteins that vary greatly in copy number and in their chemical properties. Despite this complication, nature has evolved efficient mechanisms of quality control to ensure that all proteins are biologically active, localised to the proper cellular compartment and present in appropriate quantity. This functional state must be maintained under normal as well as under stress conditions. The failure of quality control can influence cell growth and can cause severe diseases ranging for example from bacterial infections to neurodegenerative and arthritic diseases or cancer.
We are studying evolutionarily conserved cellular factors that are involved in key aspects of quality control, such as detection of misfolded proteins, signal recognition and integration into the unfolded protein response pathways and regeneration of the functional state. These studies aim at revealing the general concepts governing the underlying molecular mechanisms of protein diagnosis, repair and degradation.
The focus of our research is on the widely conserved HtrA family of serine proteases that are involved in all aspects of ATP-independent protein quality control. We showed that a protein can combine the antagonistic functions of chaperone and protease activities within a single polypeptide. Furthermore, in collaboration with Tim Clausen (IMP Vienna), it was shown that HtrAs can switch between various oligomeric states and the mechanism of activation by oligomerisation has been elucidated. In recent years, work on human HTRA1 has revealed its involvement in cancer (as a tumor suppressor), in arthritis (by remodelling of the extracellular matrix) and in Alzheimer's disease (by degrading proteins and protein fragments that aggregate to form senile plaques).
Since a number of years we are using chemical biology approaches, mainly in collaboration with Markus Kaiser (Uni Duisburg-Essen), Biotech and Pharmaceutical companies to generate tools for basic research and for drug development purposes. In addition, the structure of HTRA1 with a bound inhibitor provides leads for the search of HTRA1 modulators that are of therapeutic relevance.
Activation by substoichiometric inhibitionIn: Proceedings of the National Academy of Sciences of the United States of America Vol. 117 (2020) Nr. 3, pp. 1414 - 1418
ISSN: 1091-6490; 0027-8424
Tailored Ahp-cyclodepsipeptides as Potent Non-covalent Serine Protease InhibitorsIn: Angewandte Chemie International Edition Vol. 56 (2017) Nr. 29, Special Issue: 100th Anniversary of the Royal Australian Chemical Institute, pp. 8555 - 8558
ISSN: 1521-3773; 1433-7851
Determinants of amyloid fibril degradation by the PDZ protease HTRA1In: Nature Chemical Biology Vol. 11 (2015) Nr. 11, pp. 862 - 869
ISSN: 1552-4450; 1552-4469
Newly folded substrates inside the molecular cage of the HtrA chaperone DegQIn: Nature Structural & Molecular Biology Vol. 19 (2012) Nr. 2, pp. 152 - 157
HTRA proteases : regulated proteolysis in protein quality controlIn: Nature Reviews Molecular Cell Biology Vol. 12 (2011) Nr. 3, pp. 152 - 162
Protein quality control in the bacterial periplasmIn: Annual Review of Microbiology Vol. 65 (2011) pp. 149 - 168
ISSN: 1545-3251; 0066-4227
Structural adaptation of the plant protease Deg1 to repair photosystem II during light exposureIn: Nature Structural & Molecular Biology Vol. 18 (2011) Nr. 6, pp. 728 - 731
Substrate induced remodeling of the active site regulates human HtrA1 activityIn: Nature Structural & Molecular Biology Vol. 18 (2011) pp. 386 - 388
Determinants of structural and functional plasticity of a widely conserved protease chaperone complexIn: Nature Structural & Molecular Biology Vol. 17 (2010) Nr. 7, pp. 837 - 843
ISSN: 1545-9993; 1545-9985
Allosteric activation of HtrA protease DegP by stress signals during bacterial protein quality controlIn: Angewandte Chemie International Edition Vol. 47 (2008) Nr. 7, pp. 1332 - 1334
ISSN: 0044-8249; 0932-2140
Determinants of regulated proteolysis in signal transductionIn: Genes and Development Vol. 21 (2007) Nr. 1, pp. 6 - 10
Regulation of the σE stress response by DegS: How the PDZ domain keeps the protease inactive in the resting state and allows integration of different OMP-derived stress signals upon folding stressIn: Genes and Development Vol. 21 (2007) Nr. 20, pp. 2659 - 2670
ISSN: 0890-9369; 1549-5477
Crystal structure of the DegS stress sensor: How a PDZ domain recognizes misfolded protein and activates a proteaseIn: Cell Vol. 117 (2004) Nr. 4, pp. 483 - 494
Proteolysis as a regulatory mechanismIn: Annual Review of Genetics Vol. 38 (2004) pp. 709 - 724
ISSN: 0066-4170; 0066-4197
Crystal structure of DegP (HtrA) reveals a new protease-chaperone machineIn: Nature Vol. 416 (2002) Nr. 6879, pp. 455 - 459
ISSN: 0028-0836; 1476-4687
The HtrA family of proteases: Implications for protein composition and cell fateIn: Molecular Cell Vol. 10 (2002) Nr. 3, pp. 443 - 455