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

TY - JOUR

T1 - Variants of beta-microglobulin cleaved at lysine-58 retain the main conformational features of the native protein but are more conformationally heterogeneous and unstable at physiological temperature.

AU - Mimmi, Maria C

AU - Jørgensen, Thomas J D

AU - Pettirossi, Fabio

AU - Corazza, Alessandra

AU - Viglino, Paolo

AU - Esposito, Gennaro

AU - De Lorenzi, Ersilia

AU - Giorgetti, Sofia

AU - Pries, Mette

AU - Corlin, Dorthe B

AU - Nissen, Mogens H

AU - Heegaard, Niels H H

N1 - Keywords: Electrophoresis, Capillary; Humans; Kidney Calculi; Lysine; Magnetic Resonance Spectroscopy; Mass Spectrometry; Models, Molecular; Protein Conformation; Renal Replacement Therapy; Thermodynamics; beta 2-Microglobulin

PY - 2006

Y1 - 2006

N2 - Cleavage of the small amyloidogenic protein beta2-microglobulin after lysine-58 renders it more prone to unfolding and aggregation. This is important for dialysis-related beta2-microglobulin amyloidosis, since elevated levels of cleaved beta2-microglobulin may be found in the circulation of dialysis patients. However, the solution structures of these cleaved beta2-microglobulin variants have not yet been assessed using single-residue techniques. We here use such methods to examine beta2-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 beta2-microglobulin from which lysine-58 is removed, is much reduced compared to wild-type beta2-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 three-dimensional structure of the variants is similar to that of wild-type beta2-microglobulin at subphysiological temperatures. However, deviations do occur, especially in the arrangement of the B, D and E beta-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 beta2-microglobulin molecules. This is the first single-residue resolution study of a specific beta2-microglobulin variant that has been found circulating in dialysis patients. The instability and conformational heterogeneity of this variant suggest its involvement in beta2-microglobulin amyloidogenicity in vivo.

AB - Cleavage of the small amyloidogenic protein beta2-microglobulin after lysine-58 renders it more prone to unfolding and aggregation. This is important for dialysis-related beta2-microglobulin amyloidosis, since elevated levels of cleaved beta2-microglobulin may be found in the circulation of dialysis patients. However, the solution structures of these cleaved beta2-microglobulin variants have not yet been assessed using single-residue techniques. We here use such methods to examine beta2-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 beta2-microglobulin from which lysine-58 is removed, is much reduced compared to wild-type beta2-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 three-dimensional structure of the variants is similar to that of wild-type beta2-microglobulin at subphysiological temperatures. However, deviations do occur, especially in the arrangement of the B, D and E beta-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 beta2-microglobulin molecules. This is the first single-residue resolution study of a specific beta2-microglobulin variant that has been found circulating in dialysis patients. The instability and conformational heterogeneity of this variant suggest its involvement in beta2-microglobulin amyloidogenicity in vivo.

U2 - 10.1111/j.1742-4658.2006.05254.x

DO - 10.1111/j.1742-4658.2006.05254.x

M3 - Journal article

C2 - 16704420

SN - 1742-464X

VL - 273

SP - 2461

EP - 2474

JO - F E B S Journal

JF - F E B S Journal

IS - 11

ER -