Cytosolic proteins contribute to surface plasminogen recruitment of Neisseria meningitidis

University of Wuerzburg, Institut of Hygiene and Microbiology, Germany; University of Wuerzburg, Research Center for Infectious Diseases, Germany

^* To whom correspondence should be addressed. Email: Andreas.Knaust{at}hygiene.med.uni-giessen.de.

	Abstract

Plasminogen recruitment is a common strategy of pathogenic bacteria and results in a broad spectrum surface associated protease activity. Neisseria meningitidis has previously been shown to bind plasminogen. In this study we show by several complementary approaches that endolase, DnaK and peroxidoxin, which are usually intracellular proteins, can also be located in the outer membrane and act as plasminogen receptors. Internal binding motifs, rather than C-terminal lysine residues, are responsible for plasminogen binding of the N. meningitidis receptors. Recombinant receptor proteins inhibit plasminogen association to N. meningitidis in a concentration dependent manner. Besides binding purified plasminogen, N. meningitidis can also acquire plasminogen from human serum. Activation of N. meningitidis associated plasminogen by urokinase results in functional activity and allows the bacteria to degrade fibrinogen. Furthermore, plasmin bound to N. meningitidis is protected against inactivation by alpha2-antiplasmin.