4pz5 | pdb_00004pz5
Crystal structure of the second and third fibronectin F1 modules in complex with a fragment of BBK32 from Borrelia burgdorferi
Structural highlights
Disease[FINC_HUMAN] Defects in FN1 are the cause of glomerulopathy with fibronectin deposits type 2 (GFND2) [MIM:601894]; also known as familial glomerular nephritis with fibronectin deposits or fibronectin glomerulopathy. GFND is a genetically heterogeneous autosomal dominant disorder characterized clinically by proteinuria, microscopic hematuria, and hypertension that leads to end-stage renal failure in the second to fifth decade of life.[1] Function[FINC_HUMAN] Fibronectins bind cell surfaces and various compounds including collagen, fibrin, heparin, DNA, and actin. Fibronectins are involved in cell adhesion, cell motility, opsonization, wound healing, and maintenance of cell shape.[2] [3] [4] [5] Anastellin binds fibronectin and induces fibril formation. This fibronectin polymer, named superfibronectin, exhibits enhanced adhesive properties. Both anastellin and superfibronectin inhibit tumor growth, angiogenesis and metastasis. Anastellin activates p38 MAPK and inhibits lysophospholipid signaling.[6] [7] [8] [9] Publication Abstract from PubMedBBK32 is a fibronectin (FN)[minus]binding protein expressed on the cell surface of Borrelia burgdorferi, the causative agent of Lyme disease. There is conflicting information about where and how BBK32 interacts with FN. We have characterized interactions of a recombinant 86[minus]mer polypeptide, Bbk32, comprising the unstructured FN[minus]binding region of BBK32. Competitive enzyme[minus]linked assays utilizing various FN fragments and epitope[minus]mapped anti[minus]FN monoclonal antibodies showed that Bbk32 binding involves both the fibrin[minus] and gelatin[minus]binding domains of the 70 kDa N[minus]terminal region (FN70K). Crystallographic and NMR analyses of smaller Bbk32 peptides complexed, respectively, with 2[minus]3FNI and 8[minus]9FNI, demonstrated that binding occurs by beta[minus]strand addition. Isothermal titration calorimetry indicated that Bbk32 binds to isolated FN70K more tightly than to intact FN. In a competitive enzyme[minus]linked binding assay, complex formation with Bbk32 enhanced binding of FN with mAbIII[minus]10 to the 10FNIII module. Thus, Bbk32 binds to multiple FN type 1 modules of the FN70K region by a tandem beta[minus]zipper mechanism, and in doing so increases accessibility of FNIII modules that interact with other ligands. The similarity in the FN[minus]binding mechanism of BBK32 and previously studied streptococcal proteins suggests that the binding and associated conformational change of FN play a role in infection. Borrelia burgdorferi protein BBK32 binds to soluble fibronectin via the N-terminal 70 kDa region, causing fibronectin to undergo conformational extension.,Harris G, Ma W, Maurer LM, Potts JR, Mosher DF J Biol Chem. 2014 Jun 24. pii: jbc.M114.578419. PMID:24962582[10] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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