Nature Medicine
Published online: 9 March 2008 | doi:10.1038/nm1734
Subversion of Toll-like receptor signaling by a unique family of bacterial Toll/interleukin-1 receptor domain–containing proteins
Christine Cirl1, Andreas Wieser2, Manisha Yadav3, Susanne Duerr1, Sören Schubert2, Hans Fischer3, Dominik Stappert3, Nina Wantia1, Nuria Rodriguez1, Hermann Wagner1, Catharina Svanborg3 & Thomas Miethke1
Abstract
Pathogenic microbes have evolved sophisticated molecular strategies to subvert host defenses. Here we show that virulent bacteria interfere directly with Toll-like receptor (TLR) function by secreting inhibitory homologs of the Toll/interleukin-1 receptor (TIR) domain. Genes encoding TIR domain containing–proteins (Tcps) were identified in Escherichia coli CFT073 (TcpC) and Brucella melitensis (TcpB). We found that TcpC is common in the most virulent uropathogenic E. coli strains and promotes bacterial survival and kidney pathology in vivo. In silico analysis predicted significant tertiary structure homology to the TIR domain of human TLR1, and we show that the Tcps impede TLR signaling through the myeloid differentiation factor 88 (MyD88) adaptor protein, owing to direct binding of Tcps to MyD88. Tcps represent a new class of virulence factors that act by inhibiting TLR- and MyD88-specific signaling, thus suppressing innate immunity and increasing virulence.
Institut für Medizinische Mikrobiologie, Immunologie und Hygiene, Technische Universität München, Trogerstrasse 30, D-81675 München, Germany.
Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Ludwig-Maximilians-Universität, Pettenkoferstrasse 9a, D-80336 München, Germany.
Department of Microbiology, Immunology and Glycobiology, Institute of Laboratory Medicine, Lund University, Sölvegatan 23, 22362 Lund, Sweden.
Correspondence to: Thomas Miethke1 e-mail: Thomas.Miethke@lrz.tum.de