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Title
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Different folding transition states may result in the same native structure.
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Authors
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A.R.Viguera,
L.Serrano,
M.Wilmanns.
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Ref.
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Nat Struct Biol, 1996,
3,
874-880.
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PubMed id
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Abstract
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The crystal structures of two circular permutants of the alpha-spectrin SH3
domain with new termini within the RT loop (S19-P20s) and the distal loop
(N47-D48s) have been determined at 2.02 and 1.77 A resolution respectively. Both
fold into the same three-dimensional structure as the wild-type SH3 domain
except for the engineered loop that fuses the wild-type termini. The cleaved RT
loop in S19-P20s loses nine conserved hydrogen bonds through local hydrogen bond
unzipping; no hydrogen bond unzipping occurs in N47-D48s. The structures of the
transition states for folding of wild-type alpha-spectrin SH3 domain and the two
circular permutants have been examined by analysis of the folding kinetics of
eight strategically distributed point mutants. Unlike the native structures, the
transition states of the three proteins are considerably different, suggesting
that there is no direct relationship between these two states in a protein.
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