Homology modeling and topology prediction of FrpB protein in Neisseria meningitidis

Fateme Al Sadat Hosseini¹ Fateme Sefid² mahnaz mashroteh³ marjan babadi⁴

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Publication : 3rd International Conference On Research Science And Technology(3rstconf.com)
Abstract :
Iron is an essential nutrient for almost all bacteria, but the concentration of free iron in the human host is too low to support growth. In the extracellular compartments of the human body, iron is bound mainly to transferrin [1] and lactoferrin[2]. Many bacteria deal with iron limitation by the secretion of siderophores, which are small organic compounds that bind iron very efficiently. The Fe31-siderophore complex is bound to specific receptors on the bacterial cell surface and internalized. The transport across the outer membrane requires energy,which is provided in Escherichia coli by the inner membrane protein TonB[3]. The pathogenic neisseriae have a different mechanism of iron utilization. They are able to acquire iron directly from transferrin [4]or lactoferrin[5]. Other iron sources are hemin, hemoglobin, citrate, and the siderophore aerobactin [6,7].The uptake of iron from transferrin or lactoferrin is initiated by binding of these proteins to specific outer membrane receptors [8.9].Recently, the structural genes for these receptors have been characterized [10-13].Homology to the TonB-dependent siderophore receptors of E. coli was found. FrpB is another iron-limitation inducible outer membrane protein of Neisseria meningitidis. Its function is unknown. Previously, monoclonal antibodies was raised against this protein, most of which appeared to be bactericidal in an in vitro assay with human complement[14]. Furthermore,since the protein is expressed in large amounts in all strains under iron limitation[15], it could be an interesting vaccine candidate for meningococcal disease. Here we describe the topology and 3D structure of a novel antigen which was discovered by mining the bacterial genome and that is very effective in inducing bactericidal antibodies. This antigen is a very good candidate for inclusion in universal vaccines against N.meningitidis.
Keywords : نایسریا