title: A novel fibronectin binding motif in MSCRAMMs targets F3 modules.
abstract: BACKGROUND
  BBK32 is a surface expressed lipoprotein and fibronectin (Fn)-binding microbial surface component recognizing adhesive matrix molecule (MSCRAMM) of Borrelia burgdorferi, the causative agent of Lyme disease. Previous studies from our group showed that BBK32 is a virulence factor in experimental Lyme disease and located the Fn-binding region to residues 21-205 of the lipoprotein.
  
  
  RESULTS
  Studies aimed at identifying interacting sites between BBK32 and Fn revealed an interaction between the MSCRAMM and the Fn F3 modules. Further analysis of this interaction showed that BBK32 can cause the aggregation of human plasma Fn in a similar concentration-dependent manner to that of anastellin, the superfibronectin (sFn) inducing agent. The resulting Fn aggregates are conformationally distinct from plasma Fn as indicated by a change in available thermolysin cleavage sites. Recombinant BBK32 and anastellin affect the structure of Fn matrices formed by cultured fibroblasts and inhibit endothelial cell proliferation similarly. Within BBK32, we have located the sFn-forming activity to a region between residues 160 and 175 which contains two sequence motifs that are also found in anastellin. Synthetic peptides mimicking these motifs induce Fn aggregation, whereas a peptide with a scrambled sequence motif was inactive, suggesting that these motifs represent the sFn-inducing sequence.
  
  
  CONCLUSIONS
  We conclude that BBK32 induces the formation of Fn aggregates that are indistinguishable from those formed by anastellin. The results of this study provide evidence for how bacteria can target host proteins to manipulate host cell activities.
authors.affiliation: Institute of Biosciences and Technology, Texas A&M Health Science Center, College Station, Texas, United States of America.
authors.forename: Sabitha
authors.initials: S
authors.lastname: Prabhakaran
authors.forename: Xiaowen
authors.initials: X
authors.lastname: Liang
authors.forename: Jonathan T
authors.initials: JT
authors.lastname: Skare
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Potts
authors.forename: Magnus
authors.initials: M
authors.lastname: Höök
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism; D020816:Amino Acid Motifs; D001426:Bacterial Proteins / Q000378:metabolism* / Q000502:physiology; D001665:Binding Sites; D025065:Borrelia burgdorferi / Q000737:chemistry / Q000472:pathogenicity*; D002478:Cells, Cultured; D042783:Endothelial Cells; D005347:Fibroblasts; D005353:Fibronectins / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D008193:Lyme Disease / Q000382:microbiology; D010446:Peptide Fragments / Q000494:pharmacology; D011485:Protein Binding; D055503:Protein Multimerization; D011991:Receptors, Virus / Q000378:metabolism; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D005353:Fibronectins; D010446:Peptide Fragments; D011991:Receptors, Virus; D037521:Virulence Factors; C423921:anastellin; C106209:p35 antigen, Borrelia