SFB796 - Sub project B10


Molecular function and signal transduction of the serine protease HtrA, a novel secreted effector protein of bacterial pathogens


Project summary

Stable adhesion complexes are crucial for maintenance of the cell-to-cell integrity in healthy epithelia of humans and represent the first barrier for microbial pathogens. Alterations in these complexes are key events in the development and progression of many diseases including various cancers. One of the major proteins involved in maintaining epithelial adhesion is the tumour-suppressor and junctional transmembrane protein E-cadherin. E-cadherin also controls the transcription factor β-catenin and other signaling components, and is involved in cell morphogenesis, adhesion, recognition and communication. Inactivation of E-cadherin's adhesive properties is often a key step in tumour progression and metastasis. We have recently identified a novel secreted effector protein, the serine protease HtrA, of the foodborne pathogen Campylobacter jejuni and the gastric pathogen and type-I carcinogen Helicobacter pylori. HtrA of these microbes can be secreted into the extracellular space where it can cleave-off the extracellular domain of E-cadherin on polarized gastric or intestinal epithelial cells. Since the htrA gene is conserved in many bacterial pathogens our findings could provide a potential novel mechanism how these microbes may destroy cellular junctions in mucosal epithelial cells, in order to get access to deeper tissues and cause disease by degrading E-cadherin and probably other cellular factors. This project is therefore designed to contribute to the understanding of mechanisms underlying basic HtrA functions in bacterial pathogenesis. In particular, we would like to identify the HtrA cleavage sites in E-cadherin, characterize cleavage requirements at the amino acid level, pinpoint novel HtrA targets of host cells and to study downstream signaling events. In addition, we wish to identify the secretion pathway of HtrA across the two bacterial membranes because this could give hints how HtrA is transported and eventually even targeted directly into host cells. Our studies will take advantage of powerful technologies including fluorescence microscopy and live cell imaging as well as proteomics-based and cellular signal transduction approaches. This strategy will allow us to reconstruct novel events occurring at the pathogen - host cell interface and will enable us to pinpoint novel key determinants of this process that could be sensitive to pharmaceutical intervention.


Project relevant publications

Lind, J., Backert, S., Hoffmann, R., Eichler, J., Yamaoka, Y., Perez-Perez, G.I., Torres, J., Sticht, H., Tegtmeyer, N.   (2016)   Systematic analysis of phosphotyrosine antibodies recognizing single phosphorylated EPIYA-motifs in CagA of East Asian-type Helicobacter pylori strains.   BMC Microbiology [in press].

Backert, S., Tegtmeyer, N., Fischer, W.   (2015)   Composition, structure and function of the Helicobacter pylori cag pathogenicity island encoded type IV secretion system.   Future Microbiology 10: 955-965.

Pachathundikandi, S.K., Lind, J., Tegtmeyer, N., El-Omar, E.M., Backert, S.   (2015)   Interplay of the gastric pathogen Helicobacter pylori with toll-like receptors.   BioMedical Research International 2015: 192420.

Hartung, M.L., Gruber, D.C., Koch, K.N., Grüter, L., Rehrauer, H., Tegtmeyer, N., Backert, S., Müller, A.   (2015)   H. pylori-induced DNA strand breaks are introduced by nucleotide excision repair endonucleases and promote NF-κB target gene expression.   Cell Reports 3: 70-79.

Hammond, C.E., Beeson, C., Suarez, G., Peek, R.M. Jr., Backert, S., Smolka, A.J.   (2015)   Helicobacter pylori virulence factors affecting gastric proton pump expression and acid secretion.   American Journal of Physiology-Gastrointestinal and Liver Physiology 309: G193-201.

Perna, A.M., Rodrigues, T., Schmidt, T.P., Böhm, M., Stutz, K., Reker, D., Pfeiffer, B., Altmann, K.H., Backert, S., Wessler, S., Schneider, G.   (2015)   Fragment-Based De Novo Design Reveals a Small-Molecule Inhibitor of Helicobacter pylori HtrA.   Angewandte Chemie International, Edition in English 54: 10244-10248.

Koch, K.N., Hartung, M.L., Urban, S., Kyburz, A., Bahlmann, A.S., Lind, J., Backert, S., Taube, C., Müller, A.   (2015)   Helicobacter urease-induced activation of the TLR2/NLRP3/IL-18 axis protects against asthma.   The Journal of Clinical Investigation 125: 3297-3302.

Boehm, M., Lind, J., Backert, S., Tegtmeyer, N.   (2015)   Campylobacter jejuni serine protease HtrA plays an important role in heat tolerance, oxygen resistance, host cell adhesion, invasion, and transmigration.   European Journal of Microbiology and Immunology 5: 68-80.

Zhang, X.S., Tegtmeyer, N., Traube, L., Jindal, S., Perez-Perez, G., Sticht, H., Backert, S., Blaser, M.J.   (2015)   A Specific A/T Polymorphism in Western Tyrosine Phosphorylation B-Motifs Regulates Helicobacter pylori CagA Epithelial Cell Interactions.   PLoS Pathogens 11: e1004621.

Tenguria, S., Ansari, S.A., Khan, N., Ranjan, A., Devi, S., Tegtmeyer, N., Lind, J., Backert, S., Ahmed, N.   (2014)   Helicobacter pylori cell translocating kinase (CtkA/JHP0940) is pro-apoptotic in mouse macrophages and acts as auto-phosphorylating tyrosine kinase.   International Journal of Medical Microbiology 304: 1066-1076.

Zhang, Y.M., Noto, J.M., Hammond, C.E., Barth, J.L., Argraves, W.S., Backert, S., Peek, R.M. Jr., Smolka, A.J.   (2014)   Helicobacter pylori-induced posttranscriptional regulation of H-K-ATPase α-subunit gene expression by miRNA.   American Journal of Physiology - Gastrointestinal and Liver Physiology 306: G606-613.

Heimesaat, M.M., Alutis, M., Grundmann, U., Fischer A, Tegtmeyer N, Böhm M, Kühl, A.A., Göbel, U.B., Backert, S., Bereswill, S.   (2014)   The role of serine protease HtrA in acute ulcerative enterocolitis and extra-intestinal immune responses during Campylobacter jejuni infection of gnotobiotic IL-10 deficient mice.   Frontiers in Cellular and Infection Microbiology 4: 77.

Heimesaat, M.M., Fischer, A., Alutis, M., Grundmann, U., Boehm, M., Tegtmeyer, N., Göbel, U.B., Kühl, A.A., Bereswill, S., Backert, S.   (2014)   The impact of serine protease HtrA in apoptosis, intestinal immune responses and extra-intestinal histopathology during C. jejuni infection of infant mice.   Gut Pathogens 6: 16.

Tegtmeyer, N., Lind, J., Schmid, B., Backert, S.   (2014)   Helicobacter pylori CagL Y58/E59 mutation turns-off type IV secretion-dependent delivery of CagA into host cells.   PLoS One 9: e97782.

Lind, J., Backert, S., Pfleiderer, K., Berg, D.E., Yamaoka, Y., Sticht, H., Tegtmeyer, N.   (2014)   Systematic analysis of phosphotyrosine antibodies recognizing single phosphorylated EPIYA-motifs in CagA of Western-type Helicobacter pylori strains.   PLoS One 9: e96488.

Fernandez-Gonzalez, E., Backert, S.   (2014)   DNA transfer in the gastric pathogen Helicobacter pylori.   Journal of Gastroenterology 49: 594-604.

Pachathundikandi, S.K., Tegtmeyer, N., Backert, S.   (2013)   Signal transduction of Helicobacter pylori during interaction with host cell protein receptors of epithelial and immune cells.   Gut Microbes 4: 454-474.

Backert, S., Boehm, M., Wessler, S., Tegtmeyer, N.   (2013)   Transmigration route of Campylobacter jejuni across polarized intestinal epithelial cells: paracellular, transcellular or both?   Cell Communication and Signaling 11: 72.

Backert, S., Hofreuter, D.   (2013)   Molecular methods to investigate adhesion, transmigration, invasion and intracellular survival of the foodborne pathogen Campylobacter jejuni.   Journal of Microbiological Methods 95: 8-23.

Barden, S., Lange, S., Tegtmeyer, N., Conradi, J., Sewald, N., Backert, S., Niemann, H.H.   (2013)   A helical RGD motif promoting cell adhesion: crystal structures of the H. pylori type IV secretion system pilus protein CagL.   Structure 21: 1931-1941.

Patel, S.R., Smith, K., Letley, D.P., Cook, K.W., Memon, A.A., Ingram, R.J., Staples E., Backert, S., Zaitoun, A.M., Atherton, J.C., Robinson, K.   (2013)   Helicobacter pylori downregulates expression of human β-defensin 1 in the gastric mucosa in a type IV secretion-dependent fashion.   Cellular Microbiology 5: 2080-2092.

Boehm, M., Haenel, I., Hoy, B., Brøndsted, L., Smith, T.G., Hoover, T., Wessler, S., Tegtmeyer, N.   (2013)   Extracellular secretion of protease HtrA from Campylobacter jejuni is highly efficient and independent of its protease activity and flagellum.   European Journal of Microbiology and Immunology (Bp) 3:163-273.

Boehm M, Hoy B, Rohde M, Tegtmeyer N, Bæk KT, Oyarzabal OA, Brøndsted L, Wessler S, Backert S.   (2012)   Rapid paracellular transmigration of Campylobacter jejuni across polarized epithelial cells without affecting TER: role of proteolytic-active HtrA cleaving E-cadherin but not fibronectin.   Gut Pathogens 25: 3 .

Oyarzabal OA, Backert S, eds.   (2012)   Microbial Food Safety .   Springer New York   ISBN-Number: 978-1-4614-1176-5.

Ó'Cróinín T, Backert S .   (2012)   Host epithelial cell invasion by Campylobacter jejuni: trigger or zipper mechanism?   Front Cell Infect Microbiol 2: 25 .

Müller D, Tegtmeyer N, Brandt S, Yamaoka Y, De Poire E, Sgouras D, Wessler S, Torres J, Smolka A, Backert S.   (2012)   Hierarchic phosphorylation of the Helicobacter pylori CagA effector protein by Src and Abl tyrosine kinases.   J Clin Invest 122: 1553-1566 .

Hoy B, Löwer M, Weydig C, Carra G, Tegtmeyer N, Geppert T, Plattner P, Sewald N, Backert S, Schneider G, Wessler S.   (2010)   H. pylori HtrA is a novel secreted virulence factor which cleaves Ecadherin to disrupt intercellular adhesion.   EMBO Rep 11: 798-804 .

Tegtmeyer N, Backert S.   (2009)   Bacterial type III effectors inhibit cell lifting by targeting integrin-linked kinase.   CELL host & microbe 5: 514-516 .

Kwok T, Zabler D, Urman S, Rohde M, Hartig R, Wessler S, Misselwitz R, Berger J, Sewald N, König W, Backert S .   (2007)   Helicobacter exploits integrin for type IV secretion and kinase activation.   Nature 449: 862-866 .

Backert S, Meyer, TF .   (2006)   Type IV secretion systems and their effector proteins in bacterial pathogenesis.   Curr Opin Microbiol 9: 207-217 .