title: The response of Greek key proteins to changes in connectivity depends on the nature of their secondary structure.
abstract: What governs the balance between connectivity and topology in regulating the mechanism of protein folding? We use circular permutation to vary the order of the helices in the all-α Greek key protein FADD (Fas-associated death domain) to investigate this question. Unlike all-β Greek key proteins, where changes in the order of secondary structure cause a shift in the folding nucleus, the position of the nucleus in FADD is unchanged, even when permutation reduces the complexity significantly. We suggest that this is because local helical contacts are so dominant that permutation has little effect on the entropic cost of forming the folding nucleus whereas, in all-β Greek key proteins, all interactions in the nucleus are long range. Thus, the type of secondary structure modulates the sensitivity of proteins to changes in connectivity.
authors: University of Cambridge Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, UK.
authors: Katherine R
authors: KR
authors: Kemplen
authors: University of Cambridge Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, UK.
authors: David
authors: D
authors: De Sancho
authors: University of Cambridge Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, UK. Electronic address: jc162@cam.ac.uk.
authors: Jane
authors: J
authors: Clarke
mesh_terms: D053200:Fas-Associated Death Domain Protein / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D017510:Protein Folding; D017433:Protein Structure, Secondary
chemical_list: D053200:Fas-Associated Death Domain Protein
keywords: death domain; immunoglobulin fold; phi-value; protein folding; topology