Oligomerization of acidic fibroblast growth factor is not a prerequisite for its cell proliferation activity.
Oligomerization of fibroblast growth factors (FGFs) induced on binding to heparin or heparan sulfate proteoglycan is considered to be crucial for receptor activation and initiation of biological responses. To gain insight into the mechanism of activation of the receptor by FGFs, in the present study we investigate the effect(s) of interaction of a heparin analog, sucrose octasulfate (SOS), on the structure, stability, and biological activities of a recombinant acidic FGF from Notophthalmus viridescens (nFGF-1). SOS is found to bind to nFGF-1 and significantly increase the thermodynamic stability of the protein. Using a variety of techniques such as size-exclusion chromatography, sedimentation velocity, and multidimensional nuclear magnetic resonance (NMR) spectroscopy, it is shown that binding of SOS to nFGF-1 retains the protein in its monomeric state. In its monomeric state (complexed to SOS), n-FGF-1 shows significant cell proliferation activity. (15)N and (1)H chemical shift perturbation and the intermolecular nuclear Overhauser effects (NOEs) between SOS and nFGF-1 reveal that the ligand binds to the dense, positively charged cluster located in the groove enclosed by beta-strands 10 and 11. In addition, molecular modeling based on the NOEs observed for the SOS-nFGF-1 complex, indicates that SOS and heparin share a common binding site on the protein. In conclusion, the results of the present study clearly show that heparin-induced oligomerization of nFGF-1 is not mandatory for its cell proliferation activity.
Arunkumar
Alphonse I
AI
Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan.
Kumar
Thallampuranam Krishnaswamy S
TK
Kathir
Karuppanan Muthusamy
KM
Srisailam
Sampath
S
Wang
Han-Min
HM
Leena
Philominathan Sagaya Theresa
PS
Chi
Ya-Hui
YH
Chen
Ho-Chz
HC
Wu
Chieh-Hsi
CH
Wu
Rong-Tsun
RT
Chang
Gu-Gang
GG
Chiu
Ing-Ming
IM
Yu
Chin
C
D000818:Animals; D001665:Binding Sites; D002845:Chromatography; D016220:Fibroblast Growth Factor 1 / Q000737:chemistry* / Q000378:metabolism; D008934:Mitogens / Q000378:metabolism; D009673:Notophthalmus viridescens; D013395:Sucrose / Q000031:analogs & derivatives* / Q000378:metabolism
D008934:Mitogens; D016220:Fibroblast Growth Factor 1; D013395:Sucrose; C053081:sucrose octasulfate