Identification of a binding site on human FGF-2 for fibrinogen.
Endothelial cell adhesive interactions are mediated by both fibrinogen and fibrin, and growth is stimulated by fibroblast growth factor 2 (FGF-2). We have shown previously that FGF-2 binds specifically and with high affinity to fibrinogen and fibrin and that fibrinogen potentiates the proliferative capacity of FGF-2 and also protects it from proteolytic degradation. To further characterize this interaction we have performed FGF-2 mutagenesis to identify the interactive site. Because FGF-1 has a similar structure to FGF-2 but does not bind to fibrinogen, we used a strategy of cassette and site-directed mutagenesis, exchanging residues from FGF-1 and FGF-2 and correlating structural changes with fibrinogen binding. Two cassette interchange mutants, 2212 and 2211, contained either the third cassette or both the third and fourth cassettes from FGF-1, and neither exhibited any affinity for fibrinogen. Exchange of 5 residues (Phe95, Ser100, Asn102, Arg107, and Arg109) from FGF-2 into the corresponding sites in the third cassette of FGF-1 imparted high-affinity binding with apparent dissociation constants (Kd) of 5.3 nM and 8.6 nM, respectively, compared with 1.3 nM for wild-type FGF-2. We conclude that these 5 residues define a high-affinity binding site in FGF-2 for fibrinogen.
Peng
Hu
H
Department of Medicine, Hematology/Oncology Unit, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY 14642, USA.
Sahni
Abha
A
Fay
Philip
P
Bellum
Stephen
S
Prudovsky
Igor
I
Maciag
Thomas
T
Francis
Charles W
CW
D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D005340:Fibrinogen / Q000378:metabolism*; D016220:Fibroblast Growth Factor 1 / Q000235:genetics / Q000378:metabolism; D016222:Fibroblast Growth Factor 2 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017434:Protein Structure, Tertiary
D016222:Fibroblast Growth Factor 2; D016220:Fibroblast Growth Factor 1; D005340:Fibrinogen