apl. Prof. Dr. Sabine Hunke
Profil
Forschungsthemen2
Doctoral Scholarships from Jameel Education Foundation 17th Cohort
Quelle ↗Förderer: Andere internationale Stiftungen Zeitraum: 03/2023 - 12/2027 Projektleitung: Dr. Andrea George, Jeannette Latino, apl. Prof. Dr. Sabine Hunke
Doctoral Scholarships from Jameel Education Foundation 18th Cohort
Quelle ↗Förderer: Andere internationale Stiftungen Zeitraum: 03/2024 - 05/2028 Projektleitung: Dr. Andrea George, apl. Prof. Dr. Sabine Hunke, Jeannette Latino
Mögliche Industrie-Partner10
Stand: 26.4.2026, 19:48:44 (Top-K=20, Min-Cosine=0.4)
- 2 Treffer55.0%
- Zuwendung im Rahmen des Programms „exist – Existenzgründungen aus der Wissenschaft“ aus dem Bundeshaushalt, Einzelplan 09, Kapitel 02, Titel 68607, Haushaltsjahr 2026, sowie aus Mitteln des Europäischen Strukturfonds (hier Euro-päischer Sozialfonds Plus – ESF Plus) Förderperiode 2021-2027 – Kofinanzierung für das Vorhaben: „exist Women“T55.0%
- Zuwendung im Rahmen des Programms „exist – Existenzgründungen aus der Wissenschaft“ aus dem Bundeshaushalt, Einzelplan 09, Kapitel 02, Titel 68607, Haushaltsjahr 2026, sowie aus Mitteln des Europäischen Strukturfonds (hier Euro-päischer Sozialfonds Plus – ESF Plus) Förderperiode 2021-2027 – Kofinanzierung für das Vorhaben: „exist Women“
NVIDIA GmbH
PT24 Treffer54.1%- EU: Simulation in Multiscale Physical and Biological Systems (STIMULATE)P54.1%
- EU: Simulation in Multiscale Physical and Biological Systems (STIMULATE)
- 24 Treffer54.1%
- EU: Simulation in Multiscale Physical and Biological Systems (STIMULATE)P54.1%
- EU: Simulation in Multiscale Physical and Biological Systems (STIMULATE)
- 24 Treffer54.1%
- EU: Simulation in Multiscale Physical and Biological Systems (STIMULATE)P54.1%
- EU: Simulation in Multiscale Physical and Biological Systems (STIMULATE)
- 12 Treffer53.9%
- Interfaces in opto-electronic thin film multilayer devicesP53.9%
- Interfaces in opto-electronic thin film multilayer devices
- 28 Treffer53.6%
- Engineering of New-Generation Protein Secretion SystemsP53.6%
- Engineering of New-Generation Protein Secretion Systems
- 28 Treffer53.6%
- Engineering of New-Generation Protein Secretion SystemsP53.6%
- Engineering of New-Generation Protein Secretion Systems
- 28 Treffer53.6%
- Engineering of New-Generation Protein Secretion SystemsP53.6%
- Engineering of New-Generation Protein Secretion Systems
- 9 Treffer53.1%
- FOR 5177/2: Korrelation der Leistungsfähigkeit der Lendenwirbelsäule mit klinischen Outcomes nach einer gezielten Behandlung bei Patienten mit unteren Rückenschmerzen (TP 04)P53.1%
- FOR 5177/2: Korrelation der Leistungsfähigkeit der Lendenwirbelsäule mit klinischen Outcomes nach einer gezielten Behandlung bei Patienten mit unteren Rückenschmerzen (TP 04)
- 15 Treffer52.6%
- EU: Hybrid Organic/Inorganic Memory Elements for Integration of Electronic and Photonic Circuitry (HYMEC)P52.6%
- EU: Hybrid Organic/Inorganic Memory Elements for Integration of Electronic and Photonic Circuitry (HYMEC)
Publikationen25
Top 25 nach Zitationen — Quelle: OpenAlex (BAAI/bge-m3 embedded für Matching).
FEMS Microbiology Reviews · 508 Zitationen · DOI
Members of the superfamily of adenosine triphosphate (ATP)-binding-cassette (ABC) transport systems couple the hydrolysis of ATP to the translocation of solutes across a biological membrane. Recognized by their common modular organization and two sequence motifs that constitute a nucleotide binding fold, ABC transporters are widespread among all living organisms. They accomplish not only the uptake of nutrients in bacteria but are involved in diverse processes, such as signal transduction, protein secretion, drug and antibiotic resistance, antigen presentation, bacterial pathogenesis and sporulation. Moreover, some human inheritable diseases, like cystic fibrosis, adrenoleukodystrophy and Stargardt's disease are caused by defective ABC transport systems. Thus, albeit of major significance, details of the molecular mechanism by which these systems exert their functions are still poorly understood. In this review, recent data concerning the properties and putative role of the ATP-hydrolyzing subunits/domains are summarized and compared between bacterial and eukaryotic systems.
FEMS Microbiology Letters · 122 Zitationen · DOI
The Cpx-envelope stress system coordinates the expression and assembly of surface structures important for the virulence of Gram-negative pathogenic bacteria. It is comprised of the membrane-anchored sensor kinase CpxA, the cytosolic response regulator CpxR and the accessory protein CpxP. Characteristic of the group of two-component systems, the Cpx system responds to a broad range of stimuli including pH, salt, metals, lipids and misfolded proteins that cause perturbation in the envelope. Moreover, the Cpx system has been linked to inter-kingdom signalling and bacterial cell death. However, although signal specificity has been assumed, for most signals the mechanism of signal integration is not understood. Recent structural and functional studies provide the first insights into how CpxP inhibits CpxA and serves as sensor for misfolded pilus subunits, pH and salt. Here, we summarize and reflect on the current knowledge on signal integration by the Cpx-envelope stress system.
Journal of Biological Chemistry · 113 Zitationen · DOI
In Escherichia coli the Cpx sensor regulator system senses different kinds of envelope stress and responds by triggering the expression of periplasmic folding factors and proteases. It consists of the membrane-anchored sensor kinase CpxA, the response regulator CpxR, and the periplasmic protein CpxP. The Cpx pathway is induced in vivo by a variety of signals including pH variation, osmotic stress, and misfolded envelope proteins and is inhibited by overproduced CpxP. Because it is not clear how the Cpx pathway is able to recognize and correspond to so many different signals we overproduced, solubilized, purified, and incorporated the complete membrane-integral CpxA protein into proteoliposomes to analyze its biochemical properties in more detail. Autokinase and phosphotransfer activities of the reconstituted CpxA-His6 protein were stimulated by KCl. NaCl also stimulated the activities but to a lesser extent. Other osmotic active solutes as glycine betaine, sucrose, and proline had no effect. The system was further characterized by testing for susceptibility to sensor kinase inhibitors. Among these, Closantel inhibited the activities of solubilized but not of the reconstituted CpxA-His6 protein. We further analyzed the effect of CpxP on CpxA activities. Purified tagless CpxP protein reduced the phosphorylation status of CpxA to 50% but had no effect on CpxA phosphotransfer or phosphatase activities. As the in vitro system excludes the involvement of other factors our finding is the first biochemical evidence for direct protein-protein interaction between the sensor kinase CpxA and the periplasmic protein CpxP resulting in a down-regulation of the autokinase activity of CpxA.
Molecular Microbiology · 94 Zitationen · DOI
We previously characterized a defective-folding mutant of maltose-binding protein of Escherichia coli, MalE31, which formed periplasmic inclusion bodies. Here, we show that MalE31 aggregation does not affect bacterial growth at 30 degrees C but is lethal at 37 degrees C. Surprisingly, under mild heat shock conditions at 42 degrees C, inclusion bodies are degraded and bacterial growth is restored. One physiological consequence for the cells overproducing MalE31 was to induce an extracytoplasmic stress response by increasing the expression of the heat shock protease DegP via the CpxA/CpxR two-component signalling pathway. Furthermore, we show that the Cpx response is required to rescue the cells from the toxicity mediated by MalE31. Finally, expression of highly destabilized MalE variants that do not aggregate in the periplasm also induces the Cpx pathway, indicating that inclusion body formation is not necessary to activate this specific extracytoplasmic stress regulatory system.
European Journal of Biochemistry · 83 Zitationen · DOI
The binding-protein-dependent maltose-transport system of enterobacteria, a member of the ATP-binding-cassette (ABC) transporter superfamily, is composed of two integral membrane proteins, MalF and MalG, and two copies of an ATPase subunit, MalK, which hydrolyze ATP, thus energizing the translocation process. Isolated MalK displays spontaneous ATPase activity, whereas in the assembled MalFGK2 complex, reconstituted in liposomes, ATP hydrolysis requires stimulation by the substrate-loaded extracellular maltose-binding protein, MalE. The ATPase domains of ABC transporters, including MalK, share a unique sequence motif ('LSGGQ', 'signature sequence' or 'linker peptide') with as yet unknown function. To elucidate its role in the transport process, we investigated the consequences of mutations affecting two highly conserved residues (G137, Q140) in the MalK-ATPase of Salmonella typhimurium, by biochemical means. Residues corresponding to Q140 in other ABC proteins have not yet been studied. All mutant alleles (G137--> A, V, T; Q140--> L, K, N) fail to restore a functional transport complex in vivo. In addition, the mutations increase the repressing activity of MalK on other maltose-regulated genes when compared with wild-type MalK. Purified variants of G137 have lost the ability to hydrolyze ATP but still display nucleotide-binding activity, albeit with reduced affinity. Binding of MgATP results in similar protection against trypsin, as observed with wild-type, indicating no major change in protein structure. In contrast, the variants of Q140 differ in their properties, depending on the chemical nature of the replacement residue. MalKQ140L fails to hydrolyze ATP and exhibits a strong intrinsic resistance to trypsin in the absence of MgATP, suggesting a drastically altered conformation. In contrast, the purified mutant proteins Q140K and Q140N display ATPase activities and MgATP-induced changes in the tryptic cleavage pattern similar to those of wild-type. However, mutant transport complexes containing the Q140K or Q140N variants, when studied in proteoliposomes, are severely impaired in MalE-maltose-stimulated ATPase activity. These results are discussed with respect to the crystal structure of the homologous HisP protein [Hung, L.-W., Wang, I.X., Nikaido, K., Liu, P.-Q., Ames, G.F.-L. & Kim, S.-H. (1998) Nature (London) 396, 703-707] and are interpreted in favor of a role of the signature sequence in activating the hydrolyzing activity of MalK upon substrate-initiated conformational changes in MalF/MalG.
Journal of Biological Chemistry · 79 Zitationen · DOI
The binding protein-dependent maltose transport system of enterobacteria (MalFGK(2)), a member of the ATP-binding cassette (ABC) transporter superfamily, is composed of two integral membrane proteins, MalF and MalG, and of two copies of an ATPase subunit, MalK, which hydrolyze ATP, thus energizing the translocation process. In addition, an extracellular (periplasmic) substrate-binding protein (MalE) is required for activity. Ligand translocation and ATP hydrolysis are dependent on a signaling mechanism originating from the binding protein and traveling through MalF/MalG. Thus, subunit-subunit interactions in the complex are crucial to the transport process but the chemical nature of residues involved is poorly understood. We have investigated the proximity of residues in a conserved sequence ("EAA" loop) of MalF and MalG to residues in a helical segment of the MalK subunits by means of site-directed chemical cross-linking. To this end, single cysteine residues were introduced into each subunit at several positions and the respective malF and malG alleles were individually co-expressed with each of the malK alleles. Membrane vesicles were prepared from those double mutants that contained a functional transporter in vivo and treated with Cu(1,10-phenanthroline)(2)SO(4) or bifunctional cross-linkers. The results suggest that residues Ala-85, Lys-106, Val-114, and Val-117 in the helical segment of MalK, to different extents, participate in constitution of asymmetric interaction sites with the EAA loops of MalF and MalG. Furthermore, both MalK monomers in the complex are in close contact to each other through Ala-85 and Lys-106. These interactions are strongly modulated by MgATP, indicating a structural rearrangement of the subunits during the transport cycle. These data are discussed with respect to current transport models.
Structural Basis for Two-component System Inhibition and Pilus Sensing by the Auxiliary CpxP Protein
2011Journal of Biological Chemistry · 70 Zitationen · DOI
Bacteria are equipped with two-component systems to cope with environmental changes, and auxiliary proteins provide response to additional stimuli. The Cpx two-component system is the global modulator of cell envelope stress in gram-negative bacteria that integrates very different signals and consists of the kinase CpxA, the regulator CpxR, and the dual function auxiliary protein CpxP. CpxP both inhibits activation of CpxA and is indispensable for the quality control system of P pili that are crucial for uropathogenic Escherichia coli during kidney colonization. How these two essential biological functions of CpxP are linked is not known. Here, we report the crystal structure of CpxP at 1.45 Å resolution with two monomers being interdigitated like "left hands" forming a cap-shaped dimer. Our combined structural and functional studies suggest that CpxP inhibits the kinase CpxA through direct interaction between its concave polar surface and the negatively charged sensor domain on CpxA. Moreover, an extended hydrophobic cleft on the convex surface suggests a potent substrate recognition site for misfolded pilus subunits. Altogether, the structural details of CpxP provide a first insight how a periplasmic two-component system inhibitor blocks its cognate kinase and is released from it.
PLoS ONE · 57 Zitationen · DOI
Two-component systems, consisting of an inner membrane sensor kinase and a cytosolic response regulator, allow bacteria to respond to changes in the environment. Some two-component systems are additionally orchestrated by an accessory protein that integrates additional signals. It is assumed that spatial and temporal interaction between an accessory protein and a sensor kinase modifies the activity of a two-component system. However, for most accessory proteins located in the bacterial envelope the mechanistic details remain unclear. Here, we analyzed the interaction between the periplasmic accessory protein CpxP and the sensor kinase CpxA in Escherichia coli in dependency of three specific stimuli. The Cpx two-component system responds to envelope stress and plays a pivotal role for the quality control of multisubunit envelope structures, including type three secretion systems and pili of different pathogens. In unstressed cells, CpxP shuts off the Cpx response by a yet unknown mechanism. We show for the first time the physical interaction between CpxP and CpxA in unstressed cells using bacterial two-hybrid system and membrane-Strep-tagged protein interaction experiments. In addition, we demonstrate that a high salt concentration and the misfolded pilus subunit PapE displace CpxP from the sensor kinase CpxA in vivo. Overall, this study provides clear evidence that CpxP modulates the activity of the Cpx system by dynamic interaction with CpxA in response to specific stresses.
Biochemical and Biophysical Research Communications · 41 Zitationen · DOI
Biochimica et Biophysica Acta (BBA) - Biomembranes · 37 Zitationen · DOI
PLoS ONE · 31 Zitationen · DOI
The Cpx-envelope stress system regulates the expression of virulence factors in many Gram-negative pathogens. In Salmonella enterica serovar Typhimurium deletion of the sensor kinase CpxA but not of the response regulator CpxR results in the down regulation of the key regulator for invasion, HilA encoded by the Salmonella pathogenicity island 1 (SPI-1). Here, we provide evidence that cpxA deletion interferes with dephosphorylation of CpxR resulting in increased levels of active CpxR and consequently in misregulation of target genes. 14 potential operons were identified to be under direct control of CpxR. These include the virulence determinants ecotin, the omptin PgtE, and the SPI-2 regulator SsrB. The Tat-system and the PocR regulator that together promote anaerobic respiration of tetrathionate on 1,2-propanediol are also under direct CpxR control. Notably, 1,2-propanediol represses hilA expression. Thus, our work demonstrates for the first time the involvement of the Cpx system in a complex network mediating metabolism and virulence function.
Biochemistry · 29 Zitationen · DOI
The Cpx stress response system is induced by various environmental and cellular stimuli. It is also activated in Escherichia coli strains lacking the major phospholipid, phosphatidylethanolamine (PE). However, it is not known whether CpxA directly senses changes in the lipid bilayer or the presence of misfolded proteins due to the lack of PE in their membranes. To address this question, we used an in vitro reconstitution system and vesicles with different lipid compositions to track modulations in the activity of CpxA in different lipid bilayers. Moreover, the Cpx response was validated in vivo by monitoring expression of a PcpxP-gfp reporter in lipid-engineered strains of E. coli. Our combined data indicate that CpxA responds specifically to different lipid compositions.
Journal of Bacteriology · 28 Zitationen · DOI
The ATP-hydrolyzing subunit MalK of the ATP-binding cassette transporter for maltose of Escherichia coli is demonstrated to be accessible to digestion by proteinase K in right-side-out membrane vesicles. This finding suggests a partial transmembrane orientation of the protein.
BMC Microbiology · 27 Zitationen · DOI
This study points to the importance of the Cpx-TCS within the complex regulatory network in the E. coli response to aminoglycoside-caused stress.
MicrobiologyOpen · 27 Zitationen · DOI
Two-component systems (TCS) play a pivotal role for bacteria in stress regulation and adaptation. However, it is not well understood how these systems are modulated to meet bacterial demands. Especially, for those TCS using an accessory protein to integrate additional signals, no data concerning the role of the accessory proteins within the coordination of the response is available. The Cpx envelope stress two-component system, composed of the sensor kinase CpxA and the response regulator CpxR, is orchestrated by the periplasmic protein CpxP which detects misfolded envelope proteins and inhibits the Cpx system in unstressed cells. Using selected reaction monitoring, we observed that the amount of CpxA and CpxR, as well as their stoichiometry, are only marginally affected, but that a 10-fold excess of CpxP over CpxA is needed to switch off the Cpx system. Moreover, the relative quantification of the proteome identified not only acid stress response as a new indirect target of the Cpx system, but also suggests a general function of the Cpx system for cell wall stability.
Journal of Bacteriology · 27 Zitationen · DOI
The DctSR two-component system of Bacillus subtilis controls the expression of the aerobic C4-dicarboxylate transporter DctA. Deletion of DctA leads to an increased dctA expression. The inactivation of DctB, an extracellular binding protein, is known to inhibit the expression of dctA. Here, interaction between the sensor kinase DctS and the transporter DctA as well as the binding protein DctB was demonstrated in vivo using streptavidin (Strep) or His protein interaction experiments (mSPINE or mHPINE), and the data suggest that DctA and DctB act as cosensors for DctS. The interaction between DctS and DctB was also confirmed by the bacterial two-hybrid system (BACTH). In contrast, no indication was obtained for a direct interaction between the transporter DctA and the binding protein DctB. Activity levels of uptake of [(14)C]succinate by bacteria that expressed DctA from a plasmid were similar in the absence and the presence of DctB, demonstrating that the binding protein DctB is not required for transport. Thus, DctB is involved not in transport but in cosensing with DctS, highlighting DctB as the first example of a TRAP-type binding protein that acts as a cosensor. The simultaneous presence of DctS/DctB and DctS/DctA sensor pairs and the lack of direct interaction between the cosensors DctA and DctB indicate the formation of a tripartite complex via DctS. It is suggested that the DctS/DctA/DctB complex forms the functional unit for C4-dicarboxylate sensing in B. subtilis.
Journal of Bacteriology · 24 Zitationen · DOI
We report on novel mutations in the malK gene of Salmonella enterica serovar Typhimurium, encoding the ATPase subunit of the maltose transporter (MalFGK(2)). Biochemical analysis suggests that (i) L86 might be involved in a signaling step during substrate translocation and (ii) E306 may be critical for the structural integrity of the protein.
PROTEOMICS · 21 Zitationen · DOI
Membrane proteins are crucial for many essential cellular processes. As membrane proteins function in complexes, methods to detect and to characterize membrane protein-protein interactions are undoubtedly required. Therefore, we developed the "Membrane-Strep-tagged protein interaction experiment" (Membrane-SPINE) that combines the specific purification of a Strep-tagged membrane protein with the reversible fixation of protein complexes by formaldehyde cross-linking. In combination with MS analysis, we suggest Membrane-SPINE as a powerful tool to identify unknown interaction partners of membrane proteins in vivo.
PLoS ONE · 19 Zitationen · DOI
Two-component systems are the major means by which bacteria couple adaptation to environmental changes. All utilize a phosphorylation cascade from a histidine kinase to a response regulator, and some also employ an accessory protein. The system-wide signaling fidelity of two-component systems is based on preferential binding between the signaling proteins. However, information on the interaction kinetics between membrane embedded histidine kinase and its partner proteins is lacking. Here, we report the first analysis of the interactions between the full-length membrane-bound histidine kinase CpxA, which was reconstituted in nanodiscs, and its cognate response regulator CpxR and accessory protein CpxP. Using surface plasmon resonance spectroscopy in combination with interaction map analysis, the affinity of membrane-embedded CpxA for CpxR was quantified, and found to increase by tenfold in the presence of ATP, suggesting that a considerable portion of phosphorylated CpxR might be stably associated with CpxA in vivo. Using microscale thermophoresis, the affinity between CpxA in nanodiscs and CpxP was determined to be substantially lower than that between CpxA and CpxR. Taken together, the quantitative interaction data extend our understanding of the signal transduction mechanism used by two-component systems.
FEBS Letters · 14 Zitationen · DOI
The cysteine residues of the ABC protein MalK from Salmonella typhimurium maltose transport system (C40, C350, C360) were consecutively replaced by serines. Cys-less MalK was fully functional in maltose transport in vivo. Moreover, the activity of MalK as a repressor of other maltose-regulated genes was also retained. The absence of cysteine residues in the purified protein was verified by its failure to react with fluorescein-5-maleimide. In contrast to purified wild-type MalK, the ATPase activity of the C40S variant was insensitive to inhibition by N-ethylmaleimide.
Research in Microbiology · 12 Zitationen · DOI
Research in Microbiology · 8 Zitationen · DOI
Research in Microbiology · 7 Zitationen · DOI
InTech eBooks · 6 Zitationen · DOI
It can be estimated that most membrane proteins function in complexes (Fig. 1) (Daley 2008). Protein-protein interactions (PPIs) within these complexes can either be direct (primary interaction) or indirect (secondary interaction). Direct interactions occur either by homooligomerisation as determined for bacterial two-component systems (Gao and Stock 2009) (Fig. 1A) or by hetero-oligomerisation as shown for transport systems like ATP-binding cassette (ABC) transporters (Figs. 1B and 1C). Indirect interactions exist in large complexes as exemplified in energy producing systems such as the photosystem, bacterial surface appendages such as flagella, or secretion systems that even span two membrane systems in Gram-negative bacteria (Fig. 1D) (Jordan et al. 2001; Erhardt, Namba, and Hughes 2010). These high affinity, stable PPIs are important to form stable functional complexes (Jura et al. 2011). In addition, low affinity, transient PPIs are needed for proteins that regulate the activity of a stable complex and have been described for the interaction between e.g. ABC protein and inhibitory EIIaGlc (Bluschke et al. 2007; Bluschke, Volkmer-Engert, and Schneider 2006), substrate binding protein and ABC transporter (Locher, Lee, and Rees 2002) or accessory proteins in two-component systems (Heermann and Jung 2010; Buelow and Raivio 2010; Zhou et al. 2011).
Journal of Visualized Experiments · 5 Zitationen · DOI
Membrane proteins are essential for cell viability and are therefore important therapeutic targets1-3. Since they function in complexes4, methods to identify and characterize their interactions are necessary5. To this end, we developed the Membrane Strep-protein interaction experiment, called Membrane-SPINE6. This technique combines in vivo cross-linking using the reversible cross-linker formaldehyde with affinity purification of a Strep-tagged membrane bait protein. During the procedure, cross-linked prey proteins are co-purified with the membrane bait protein and subsequently separated by boiling. Hence, two major tasks can be executed when analyzing protein-protein interactions (PPIs) of membrane proteins using Membrane-SPINE: first, the confirmation of a proposed interaction partner by immunoblotting, and second, the identification of new interaction partners by mass spectrometry analysis. Moreover, even low affinity, transient PPIs are detectable by this technique. Finally, Membrane-SPINE is adaptable to almost any cell type, making it applicable as a powerful screening tool to identify PPIs of membrane proteins.
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- Name
- apl. Prof. Dr. Sabine Hunke
- Titel
- apl. Prof. Dr.
- Fakultät
- Vizepräsident(in) für Forschung
- Institut
- Humboldt Graduate School
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- +49 30 2093-89700
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- 26.4.2026, 01:06:31