HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: jimmunol.0803226v1 183/4/2593    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Google Scholar Articles by Hallström, T. Articles by Riesbeck, K. PubMed PubMed Citation Articles by Hallström, T. Articles by Riesbeck, K.

Nontypeable Haemophilus influenzae Protein E Binds Vitronectin and Is Important for Serum Resistance¹

Teresia Hallström^*, Anna M. Blom, Peter F. Zipfel and Kristian Riesbeck²

^* Medical Microbiology and Medical Protein Chemistry, Department of Laboratory Medicine, Lund University, University Hospital Malmö, Malmö, Sweden; Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell Institute, Friedrich Schiller University, Jena, Germany

Nontypeable Haemophilus influenzae (NTHi) commonly causes local disease in the upper and lower respiratory tract and has recently been shown to interfere with both the classical and alternative pathways of complement activation. The terminal pathway of the complement system is regulated by vitronectin that is a component of both plasma and the extracellular matrix. In this study, we identify protein E (PE; 16 kDa), which is a recently characterized ubiquitous outer membrane protein, as a vitronectin-binding protein of NTHi. A PE-deficient NTHi mutant had a markedly reduced survival in serum compared with the PE-expressing isogenic NTHi wild type. Moreover, the PE-deficient mutant showed a significantly decreased binding to both soluble and immobilized vitronectin. In parallel, PE-expressing Escherichia coli bound soluble vitronectin and adhered to immobilized vitronectin compared with controls. Surface plasmon resonance technology revealed a K_D of 0.4 µM for the interaction between recombinant PE and immobilized vitronectin. Moreover, the PE-dependent vitronectin-binding site was located at the heparin-binding domains of vitronectin and the major vitronectin-binding domain was found in the central core of PE (aa 84–108). Importantly, vitronectin bound to the surface of NTHi 3655 reduced membrane attack complex-induced hemolysis. In contrast to incubation with normal human serum, NTHi 3655 showed a reduced survival in vitronectin-depleted human serum, thus demonstrating that vitronectin mediates a protective role at the bacterial surface. Our findings show that PE, by binding vitronectin, may play an important role in NTHi pathogenesis.

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ This work was supported by grants from the Alfred Österlund, the Anna and Edwin Berger, the Crafoord, the Marianne and Marcus Wallenberg, and the Greta and Johan Kock Foundations, the Swedish Medical Research Coucnil, the Swedish Society of Medicine, the Cancer Foundation at the University Hospital in Malmö, and the Skane County Council’s Research and Development Foundation.

² Address correspondence and reprint requests to Dr. Kristian Riesbeck, Medical Microbiology, Department of Laboratory Medicine, University Hospital Malmö, Lund University, SE-205 02 Malmö, Sweden. E-mail address: kristian.riesbeck{at}med.lu.se

³ Abbreviations used in this paper: MAC, membrane attack complex; C4BP, C4b-binding protein; ECM, extracellular matrix; NTHi, nontypeable Haemophilus influenzae; Hib, H. influenzae type b; Hsf, H. influenzae surface fibril; NHS, normal human serum; OMP, outer membrane protein; pAb, polyclonal antibody; PE, protein E; MID, Moraxella IgD-binding protein.