Dataset Information

Conformational differences in the light chain constant domain of immunoglobulin G and free light chain may influence proteolysis in AL amyloidosis

ABSTRACT: Immunoglobulin light chain amyloidosis (AL) is a life-threatening disease caused by the deposition of monoclonal light chain (LC) and its fragments containing variable (VL) and portions of constant (CL) domains. AL patients feature either monoclonal free LCs circulating as covalent and noncovalent homodimers, or monoclonal immunoglobulin (Ig) wherein LC and heavy chain (HC) form disulfide-linked heterodimers, or both. The role of monoclonal Ig in AL amyloidosis is unclear as prior studies focused on full-length free LC or VL domain. We used a mammalian cell-based expression system to generate four AL patient-derived full-length IgGs, two non-AL IgG controls, and six corresponding free LC proteins derived from IGLV6-57 germline precursor. Comparison of proteins’ secondary structure, thermal stability, proteolytic susceptibility, and disulfide link reduction suggested the importance of local vs. global conformational stability. Analysis of IgGs vs. corresponding free LCs using hydrogen-deuterium exchange mass spectrometry revealed major differences in the local conformation/dynamics of CL domain. In all IgGs vs. LCs, segment containing ß-strand and -helix ßAC-ACBC was more dynamic/exposed while segment ßDC-ßEC was less dynamic/exposed. Notably, these segments overlapped proteolysis-prone regions whose in vivo cleavage generates LC fragments found in AL deposits. Altogether, the results suggest that preferential cleavage in segments ßAC-ACBC of free LC or ßDC-ßEC of IgG helps generate amyloid protein precursors. We propose that protecting these segments using small-molecule stabilizers, which bind to the interfacial cavities CL-CL in free LC or CL-CH1 in IgG, is a potential therapeutic strategy to complement current approaches targeting VL-VL or VL-CL stabilization.

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ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Thomas Wales

LAB HEAD: Thomas E. Wales

PROVIDER: PXD055570 | Pride | 2025-12-08

REPOSITORIES: Pride

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Conformational Differences in the Light Chain Constant Domain of Immunoglobulin G and Free Light Chain May Influence Proteolysis in AL Amyloidosis.

Klimtchuk Elena S ES Prokaeva Tatiana T Spencer Brian H BH Wong Sherry S Ghosh Shreya S Urdaneta Angela A Morgan Gareth G Wales Thomas E TE Gursky Olga O

Journal of molecular biology 20241028 23

Immunoglobulin light chain amyloidosis (AL) is a life-threatening disease caused by the deposition of light chain (LC) and its fragments containing variable (V<sub>L</sub>) and portions of constant (C<sub>L</sub>) domains. AL patients feature either monoclonal free LCs (FLCs) circulating as covalent and noncovalent homodimers, or monoclonal immunoglobulin (Ig) wherein the LC and heavy chain (HC) form disulfide-linked heterodimers, or both. The role of full-length Ig in AL amyloidosis is unclear ...[more]

PMID: 39490919

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