Leptospiral immunoglobulin-like proteins interact with human complement regulators factor H, FHL-1, FHR-1, and C4BP

J Infect Dis. 2012 Mar 15;205(6):995-1004. doi: 10.1093/infdis/jir875. Epub 2012 Jan 30.

Abstract

Leptospira, the causative agent of leptospirosis, interacts with several host molecules, including extracellular matrix components, coagulation cascade proteins, and human complement regulators. Here we demonstrate that acquisition of factor H (FH) on the Leptospira surface is crucial for bacterial survival in the serum and that these spirochetes, besides interacting with FH, FH related-1, and C4b binding protein (C4BP), also acquire FH like-1 from human serum. We also demonstrate that binding to these complement regulators is mediated by leptospiral immunoglobulin-like (Lig) proteins, previously shown to interact with fibronectin, laminin, collagen, elastin, tropoelastin, and fibrinogen. Factor H binds to Lig proteins via short consensus repeat domains 5 and 20. Competition assays suggest that FH and C4BP have distinct binding sites on Lig proteins. Moreover, FH and C4BP bound to immobilized Ligs display cofactor activity, mediating C3b and C4b degradation by factor I. In conclusion, Lig proteins are multifunctional molecules, contributing to leptospiral adhesion and immune evasion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Adhesion
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Binding Sites
  • Blood Proteins / metabolism*
  • Cloning, Molecular
  • Complement C3b / metabolism
  • Complement C3b Inactivator Proteins / metabolism*
  • Complement C4b-Binding Protein / metabolism
  • Complement Factor H / metabolism
  • Gene Expression Regulation, Bacterial
  • Histocompatibility Antigens / metabolism*
  • Humans
  • Immune Evasion
  • Immunoglobulins / chemistry
  • Leptospira / genetics
  • Leptospira / metabolism
  • Leptospira / pathogenicity*
  • Leptospirosis / immunology*
  • Leptospirosis / microbiology
  • Plasmids

Substances

  • Bacterial Proteins
  • Blood Proteins
  • C4BPA protein, human
  • CFH protein, human
  • CFHR1 protein, human
  • Complement C3b Inactivator Proteins
  • Complement C4b-Binding Protein
  • Histocompatibility Antigens
  • Immunoglobulins
  • factor H-related protein 1
  • Complement C3b
  • Complement Factor H