Cleavage of the small amyloidogenic protein b2-microglobulin after lysine- 58 renders it more prone to unfolding and aggregation. This is important for dialysis-related b2-microglobulin amyloidosis, since elevated levels of cleaved b2-microglobulin may be found in the circulation of dialysis patients. However, the solution structures of these cleaved b2-microglobulin variants have not yet been assessed using single-residue techniques. We here use such methods to examine b2-microglobulin cleaved after lysine-58 and the further processed variant (found in vivo) from which lysine-58 is removed. We find that the solution stability of both variants, especially of b2-microglobulin from which lysine-58 is removed, is much reduced compared to wild-type b2-microglobulin and is strongly dependent on temperature and protein concentration. 1H-NMR spectroscopy and amide hydrogen (1H⁄ 2H) exchange monitored by MS show that the overall threedimensional structure of the variants is similar to that of wild-type b2-microglobulin at subphysiological temperatures. However, deviations do occur, especially in the arrangement of the B, D and E b-strands close to the D–E loop cleavage site at lysine-58, and the experiments suggest conformational heterogeneity of the two variants. Two-dimensional NMR spectroscopy indicates that this heterogeneity involves an equilibrium between the native-like fold and at least one conformational intermediate resembling intermediates found in other structurally altered b2-microglobulin molecules. This is the first single-residue resolution study of a specific b2-microglobulin variant that has been found circulating in dialysis patients. The instability and conformational heterogeneity of this variant suggest its involvement in b2-microglobulin amyloidogenicity in vivo.

Variants of Beta2-microglobulin cleaved at lysine-58 retain the main conformational features of the native protein but are more conformationally heterogeneous and unstable at phylogical temperature.

CORAZZA Alessandra;
2006-01-01

Abstract

Cleavage of the small amyloidogenic protein b2-microglobulin after lysine- 58 renders it more prone to unfolding and aggregation. This is important for dialysis-related b2-microglobulin amyloidosis, since elevated levels of cleaved b2-microglobulin may be found in the circulation of dialysis patients. However, the solution structures of these cleaved b2-microglobulin variants have not yet been assessed using single-residue techniques. We here use such methods to examine b2-microglobulin cleaved after lysine-58 and the further processed variant (found in vivo) from which lysine-58 is removed. We find that the solution stability of both variants, especially of b2-microglobulin from which lysine-58 is removed, is much reduced compared to wild-type b2-microglobulin and is strongly dependent on temperature and protein concentration. 1H-NMR spectroscopy and amide hydrogen (1H⁄ 2H) exchange monitored by MS show that the overall threedimensional structure of the variants is similar to that of wild-type b2-microglobulin at subphysiological temperatures. However, deviations do occur, especially in the arrangement of the B, D and E b-strands close to the D–E loop cleavage site at lysine-58, and the experiments suggest conformational heterogeneity of the two variants. Two-dimensional NMR spectroscopy indicates that this heterogeneity involves an equilibrium between the native-like fold and at least one conformational intermediate resembling intermediates found in other structurally altered b2-microglobulin molecules. This is the first single-residue resolution study of a specific b2-microglobulin variant that has been found circulating in dialysis patients. The instability and conformational heterogeneity of this variant suggest its involvement in b2-microglobulin amyloidogenicity in vivo.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11390/880405
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