J Mol Biol 371(1), 256-268 2007

Spackling the crack: stabilizing human fibroblast growth factor-1 by targeting the N-and C-terminus β-strand interactions

Departments of Chemistry and Biochemistry and Biomedical Science and the Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306-4380, USA.

The β-trefoil protein human fibroblast growth factor-1 (FGF-1) is made up of a six-stranded anti-parallel β-barrel closed off on one end by three β-hairpins, thus exhibiting a three-fold axis of structural symmetry. The N- and C-terminus β-strands hydrogen bond to each other and their interaction is postulated from both NMR and x-ray structure data to be important in folding and stability. Specific mutations within the adjacent N- and C-terminus â-strands of FGF-1 are shown to provide a substantial increase in stability. This increase is largely correlated with an increased folding rate constant, and with a smaller but significant decrease in the unfolding rate constant. A series of stabilizing mutations are subsequently combined and result in a doubling of the ΔG of unfolding. When taken in the context of previous studies of stabilizing mutations, the results indicate that although FGF-1 is known for generally poor thermal stability, the β-trefoil architecture appears capable of substantial thermal stability. Targeting stabilizing mutations within the N- and C-terminus β-strand interactions of a β-barrel architecture may be a generally useful approach to increase protein stability. Such stabilized mutations of FGF-1 are shown to exhibit significant increases in effective mitogenic potency, and may prove useful as "second generation" forms of FGF-1 for application in angiogenic therapy.

PMID: [PubMed]

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