Spackling the crack: stabilizing human fibroblast growth factor-1 by targeting the N and C terminus beta-strand interactions.
The beta-trefoil protein human fibroblast growth factor-1 (FGF-1) is made up of a six-stranded antiparallel beta-barrel closed off on one end by three beta-hairpins, thus exhibiting a 3-fold axis of structural symmetry. The N and C terminus beta-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 beta-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 DeltaG value 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 beta-trefoil architecture appears capable of substantial thermal stability. Targeting stabilizing mutations within the N and C terminus beta-strand interactions of a beta-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.
Dubey
Vikash Kumar
VK
Department of Biomedical Sciences, Florida State University, Tallahassee FL 32306, USA.
Lee
Jihun
J
Somasundaram
Thayumana
T
Blaber
Sachiko
S
Blaber
Michael
M
D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D016220:Fibroblast Growth Factor 1 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013816:Thermodynamics
D016220:Fibroblast Growth Factor 1