Rl. Isaacson et al., Equilibria and kinetics of folding of gelsolin domain 2 and mutants involved in familial amyloidosis-Finnish type, P NAS US, 96(20), 1999, pp. 11247-11252
Citations number
37
Categorie Soggetti
Multidisciplinary
Journal title
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Mutations D187N and D187Y in domain 2 of the actin-regulating protein gelso
lin cause familial amyloidosis-Finnish type (FAF). We have constructed and
expressed a recombinant version of gelsolin domain 2 that is sufficiently s
table for kinetic and equilibrium measurements. The wildtype domain and the
two amyloidogenic mutants fold via simple two-state kinetics without the a
ccumulation of an intermediate. Unfolding kinetics exhibits significant cur
vature with increasing urea concentration, indicating that the transition s
tate for unfolding becomes more native-like under increasingly denaturing c
onditions in accordance with the Hammond postulate. Mutations D187N and D18
7Y destabilize gelsolin domain 2 by 1.22 and 2.16 kcal.mol(-1) (1 kcal = 4.
18 kJ) respectively. The mutations do not prevent disulfide bond formation
despite their direct contiguity with a cysteine residue involved in disulfi
de linkage. The destabilization conferred on gelsolin domain 2 by the FAF m
utations is sufficient to predict that an appreciable fraction is unfolded
and, therefore, extremely susceptible to proteolysis at body temperature.