Solution structure of the N-terminal F1 module pair from human fibronectin

Multiple sites within the N-terminal domain ((1-5)F1) of fibronectin have b een implicated previously in fibronectin matrix assembly, heparin binding, and binding to cell surface proteins of pathogenic bacteria. The solution s tructure of (1)F(2)F1, the N-terminal F1 module pair from human fibronectin , has been determined using NMR spectroscopy. Both modules in the pair conf orm to the F1 consensus fold. In (4)F1(5)F1, the only other F1 module pair structure available, there is a well-defined intermodule interface; in (1)F 1(2)F1, however, there is no detectable interface between the modules. Comp arison of the backbone N-15-{H-1} NOE values for both module pairs confirms that the longer intermodule sequence in (1)F1(2)F1 is F1exible and that th e stabilization of the (4)F1 C-D loop observed in (4)F1(5)F1, as a result o f the intermodule interface, is not observed in (1)F1(2)F1.