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Visualization of Bacterial Toxin Induced Responses Using Live Cell Fluorescence Microscopy
Published on: October 1, 2012
alpha2-Macroglobulin-proteinase complexes protect Streptococcus pyogenes from killing by the antimicrobial peptide
Patrik Nyberg1, Magnus Rasmussen, Lars Björck
1Section for Clinical and Experimental Infectious Medicine, Department of Cell and Molecular Biology, Lund University, BMC, B14, Tornavägen 10, S-22184 Lund, Sweden. Patrik.Nyberg@medkem.lu.se
Abstract:
The significant human bacterial pathogen Streptococcus pyogenes expresses GRAB, a surface protein that binds alpha(2)-macroglobulin (alpha(2)M), a major proteinase inhibitor of human plasma. alpha(2)M inhibits proteolysis by trapping the proteinase, which, however, still remains proteolytically active against smaller peptides that can penetrate the alpha(2)M-proteinase complex. Here we report that SpeB, a cysteine proteinase secreted by S. pyogenes, is trapped by alpha(2)M bound to protein GRAB. As a consequence, SpeB is retained at the bacterial surface and protects S. pyogenes against killing by the antibacterial peptide LL-37.
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