Identification and characterization of the factor H and FHL-1 binding complement regulator-acquiring surface protein 1 of the Lyme disease spirochete Borrelia spielmanii sp. nov.
Borrelia spielmanii, one of the etiological agents of Lyme disease found in Europe, evades host complement-mediated killing by recruitment of the immune regulators factor H and FHL-1 from human serum. Serum-resistant and intermediate serum-resistant isolates express up to 3 distinct complement regulator-acquiring surface proteins (CRASPs) that bind factor H and/or FHL-1. The present study describes identification and functional characterization of BsCRASP-1 as the dominant factor H and FHL-1 binding protein of B. spielmanii. BsCRASP-1 is a 27.7kDa outer surface lipoprotein, which after processing has a predicted mass of 24.9kDa. BsCRASP-1 is encoded by a single copy gene, cspA, that maps to a linear plasmid of approximately 55kb. Ligand affinity blot techniques revealed that both native and recombinant BsCRASP-1 from different isolates can strongly bind FHL-1, but only weakly factor H. Deletion mutants of recombinant BsCRASP-1 were generated and a high-affinity binding site for factor H and FHL-1 was mapped to its carboxy-terminal 10-amino-acid residue domain. Similarly, the dominant binding site of factor H and FHL-1 was localized to short consensus repeats (SCRs) 5-7. Factor H and FHL-1 maintained cofactor activity for factor I-mediated C3b inactivation when bound to full-length BsCRASP-1 but not to a deletion mutant lacking the carboxy-terminal 10-amino-acid residue domain. In conclusion, BsCRASP-1 binds the host immune regulators factor H and FHL-1, and is suggested to represent a key molecule of B. spielmanii for complement resistance. Thus, BsCRASP-1 most likely contributes to persistence of B. spielmanii and to pathogenesis of Lyme disease.
Herzberger
Pia
P
Institute of Medical Microbiology and Infection Control, University Hospital of Frankfurt, Frankfurt, Germany.
Siegel
Corinna
C
Skerka
Christine
C
Fingerle
Volker
V
Schulte-Spechtel
Ulrike
U
Wilske
Bettina
B
Brade
Volker
V
Zipfel
Peter F
PF
Wallich
Reinhard
R
Kraiczy
Peter
P
D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics; D001665:Binding Sites; D001898:Borrelia / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D017242:Complement Factor H / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005060:Europe; D017353:Gene Deletion; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D060588:LIM Domain Proteins; D008193:Lyme Disease / Q000382:microbiology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009124:Muscle Proteins / Q000378:metabolism*; D010957:Plasmids; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D025941:Protein Interaction Mapping; D017422:Sequence Analysis, DNA; D037521:Virulence Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004269:DNA, Bacterial; C101149:FHL1 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D060588:LIM Domain Proteins; D009124:Muscle Proteins; D037521:Virulence Factors; C062260:cold shock protein CS7.4, Bacteria; D017242:Complement Factor H