Ursprüngliche cytolytische und antimikrobielle Mechanismen von humanpathogenen und freilebenden Protozoen im Vergleich mit denen höherer Organismen
Final Report Abstract
Pore-forming proteins are well-known as virulence factors produced by pathogenic bacteria and protozoan parasites. Moreover, the principle of target cell membrane perforation by poreforming peptides and proteins is also employed by the defensive systems of plants and animals including humans. In pathogenic amoebae, pore-forming proteins are considered essential for tissue destruction caused by these parasites. Acanthamoebae as pathogens have become of rising importance during the last decades. Infection with Acanthamoebae can cause severe diseases such as vision-threatening acanthamoeba keratitis in wearers of contact lenses and fatal granulomatous amoebic encephalitis. Moreover, Acanthamoebae are dubbed `Trojan horses´ as they can carry a variety of bacterial pathogens such as Legionellae and mycobacteria that may eventually infect the human body and cause fatal diseases such as Legionaires disease and tuberculosis, respectively. We recently determined that also Acanthamoeba culbertsoni produces soluble protein toxins that create pores inside membranes. In this project, we investigated the structure and function of acanthaporin, the first pore-forming toxin from Acanthamoebae. Acanthaporin is cytotoxic for human cells and exerts antimicrobial activity against a variety of bacterial strains by permeabilizing their membranes. The tertiary structures of the acanthaporin active monomer and the inactive dimer solved by NMR spectroscopy revealed a currently unknown protein fold and a pH-dependent trigger mechanism of activation.
Publications
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Cell-free synthesis and combinatorial selective 15N-labeling of the cytotoxic protein amoebapore A from Entamoeba histolytica. Protein Expr Purif. 2009 Nov; 68(1):22-27
Xun Y, Tremouilhac P, Carraher C, Gelhaus C, Ozawa K, Otting G, Dixon NE, Leippe M, Grötzinger J, Dingley AJ, Kralicek AV
