Ak. Chamberlain et al., Characterization of the structure and dynamics of amyloidogenic variants of human lysozyme by NMR spectroscopy, PROTEIN SCI, 10(12), 2001, pp. 2525-2530
The structures and dynamics of the native states of two mutational variants
of human lysozyme, I56T and D67H, both associated with non-neuropathic sys
temic amyloidosis, have been investigated by NMR spectroscopy. The H-1 and
N-15 main-chain amide chemical shifts of the I56T variant are very similar
to those of the wild-type protein, but those of the D67H variant are greatl
y altered for 28 residues in the beta -domain. This finding is consistent w
ith the X-ray crystallographic analysis, which shows that the structure of
this variant is significantly altered from that of the wild-type protein in
this region. The H-1-N-15 heteronuclear NOE values show that, with the exc
eption of V121, every residue in the wild-type and I56T proteins is located
in tightly packed structures characteristic of the native states of most p
roteins. In contrast, D67H has a region of substantially increased mobility
as shown by a dramatic decrease in heteronuclear NOE values of residues ne
ar the site of mutation. Despite this unusual flexibility, the D67H variant
has no greater propensity to form amyloid fibrils in vivo or in vitro than
has I56T. This finding indicates that it is the increased ability of the v
ariants to access partially folded conformations, rather than intrinsic cha
nges in their native state properties,. that is the origin of their amyloid
ogenicity.