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9 záznamů v Medvik Filtry

Článek

Kingella kingae RtxA toxin interacts with sialylated gangliosides

Rahman, Waheed Ur
Autor Rahman, Waheed Ur Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
Fiser, Radovan
Autor Fiser, Radovan Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
Osicka, Radim
Autor Osicka, Radim Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic. Electronic address: osicka@biomed.cas.cz

Microbial pathogenesis. 2023 ; 181 (-) : 106200. [pub] 20230613

Microb Pathog
ISSN 1096-1208
Medvik
Zdroj

The membrane-damaging RTX family cytotoxin RtxA is a key virulence factor of the emerging pediatric pathogen Kingella kingae, but little is known about the mechanism of RtxA binding to host cells. While we have previously shown that RtxA binds cell surface glycoproteins, here we demonstrate that the toxin also binds different types of gangliosides. The recognition of gangliosides by RtxA depended on sialic acid side groups of ganglioside glycans. Moreover, binding of RtxA to epithelial cells was significantly decreased in the presence of free sialylated gangliosides, which inhibited cytotoxic activity of the toxin. These results suggest that RtxA utilizes sialylated gangliosides as ubiquitous cell membrane receptor molecules on host cells to exert its cytotoxic action and support K. kingae infection.

Článek

EHK - 1299 Bakteriologická diagnostika (PT#M/5-4/2022)

Šafránková, Renáta
Autor Autorita
Jakubů, Vladislav
Autor Autorita
Urbášková, Pavla
Autor Autorita

Zprávy Centra epidemiologie a mikrobiologie (2011, Print). 2023 ; 32 (1) : 41-43.

ISSN 1804-8668
Medvik
Zdroj

Článek online

Binding of Kingella kingae RtxA Toxin Depends on Cell Surface Oligosaccharides, but Not on β2 Integrins

International journal of molecular sciences. 2020 ; 21 (23) : . [pub] 20201129

Int J Mol Sci
ISSN 1422-0067
Medvik
Zdroj

The Gram-negative coccobacillus Kingella kingae is increasingly recognized as an important invasive pediatric pathogen that causes mostly bacteremia and skeletal system infections. K. kingae secretes an RtxA toxin that belongs to a broad family of the RTX (Repeats in ToXin) cytotoxins produced by bacterial pathogens. Recently, we demonstrated that membrane cholesterol facilitates interaction of RtxA with target cells, but other cell surface structures potentially involved in toxin binding to cells remain unknown. We show that deglycosylation of cell surface structures by glycosidase treatment, or inhibition of protein N- and O-glycosylation by chemical inhibitors substantially reduces RtxA binding to target cells. Consequently, the deglycosylated cells were more resistant to cytotoxic activity of RtxA. Moreover, experiments on cells expressing or lacking cell surface integrins of the β2 family revealed that, unlike some other cytotoxins of the RTX family, K. kingae RtxA does not bind target cells via the β2 integrins. Our results, hence, show that RtxA binds cell surface oligosaccharides present on all mammalian cells but not the leukocyte-restricted β2 integrins. This explains the previously observed interaction of the toxin with a broad range of cell types of various mammalian species and reveals that RtxA belongs to the group of broadly cytolytic RTX hemolysins.

Článek online

Cytotoxic activity of Kingella kingae RtxA toxin depends on post-translational acylation of lysine residues and cholesterol binding

Emerging microbes & infections. 2018 ; 7 (1) : 178. [pub] 20181107

Emerg Microbes Infect
ISSN 2222-1751
Medvik
Zdroj

Kingella kingae is a member of the commensal oropharyngeal flora of young children. Improvements in detection methods have led to the recognition of K. kingae as an emerging pathogen that frequently causes osteoarticular infections in children and a severe form of infective endocarditis in children and adults. Kingella kingae secretes a membrane-damaging RTX (Repeat in ToXin) toxin, RtxA, which is implicated in the development of clinical infections. However, the mechanism by which RtxA recognizes and kills host cells is largely unexplored. To facilitate structure-function studies of RtxA, we have developed a procedure for the overproduction and purification of milligram amounts of biologically active recombinant RtxA. Mass spectrometry analysis revealed the activation of RtxA by post-translational fatty acyl modification on the lysine residues 558 and/or 689 by the fatty-acyltransferase RtxC. Acylated RtxA was toxic to various human cells in a calcium-dependent manner and possessed pore-forming activity in planar lipid bilayers. Using various biochemical and biophysical approaches, we demonstrated that cholesterol facilitates the interaction of RtxA with artificial and cell membranes. The results of analyses using RtxA mutant variants suggested that the interaction between the toxin and cholesterol occurs via two cholesterol recognition/interaction amino acid consensus motifs located in the C-terminal portion of the pore-forming domain of the toxin. Based on our observations, we conclude that the cytotoxic activity of RtxA depends on post-translational acylation of the K558 and/or K689 residues and on the toxin binding to cholesterol in the membrane.