Characterization of MspA, an immunogenic autotransporter protein that mediates adhesion to epithelial and endothelial cells in Neisseria meningitidis.
A novel putative autotransporter protein (NMB1998) was identified in the available genomic sequence of meningococcal strain MC58 (ET-5; ST-32). The mspA gene is absent from the genomic sequences of meningococcal strain Z2491 (ET-IV; ST-4) and the gonococcal strain FA1090. An orthologue is present in the meningococcal strain FAM18 (ET-37; ST-11), but the sequence contains a premature stop codon, suggesting that the protein may not be expressed in this strain. MspA is predicted to be a 157-kDa protein with low cysteine content, and it exhibits 36 and 33% identity to the meningococcal autotransporter proteins immunoglobulin A1 (IgA1) protease and App, respectively. Search of the Pfam database predicts the presence of IgA1 protease and autotransporter beta-barrel domains. MspA was cloned, and a recombinant protein of the expected size was expressed and after being affinity purified was used to raise rabbit polyclonal monospecific antiserum. Immunoblot studies showed that ca. 125- and 95-kDa fragments of MspA are secreted in meningococcal strain MC58, which are absent from the isogenic mutant. Secretion of MspA was shown to be modified in an AspA isogenic mutant. A strain survey showed that MspA is expressed by all ST-32 and ST-41/44 (lineage 3) strains, but none of the ST-8 (A4) strains examined. Sera from patients convalescing from meningococcal disease were shown to contain MspA-specific antibodies. In bactericidal assays, anti-MspA serum was shown to kill the homologous strain (MC58) and another ST-32 strain. Escherichia coli-expressing recombinant MspA was shown to adhere to both human bronchial epithelial cells and brain microvascular endothelial cells.
Turner
D P J
DP
Institute of Infections, Immunity and Inflammation, School of Molecular Medical Sciences, University Hospital, Queen's Medical Centre, Nottingham NG7 2UH, United Kingdom. david.turner@nottingham.ac.uk
Marietou
A G
AG
Johnston
L
L
Ho
K K L
KK
Rogers
A J
AJ
Wooldridge
K G
KG
Ala'Aldeen
D A A
DA
D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000502:physiology*; D001770:Blood Bactericidal Activity; D042783:Endothelial Cells / Q000382:microbiology*; D004847:Epithelial Cells / Q000382:microbiology; D004926:Escherichia coli / Q000502:physiology; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D009345:Neisseria meningitidis / Q000502:physiology*; D011817:Rabbits
D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D008565:Membrane Proteins