Physiochemical consequences of amino acid variations that contribute to fibril formation by immunoglobulin light chains.

Journal Article · Mon Mar 01 04:00:00 EST 1999 · Protein Sci.

OSTI ID:938365

Raffen, R; Wunschl, C; Pokkuluri, P R; Dave, P; Wilkins-Stevens, P; Schiffer, M; Stevens, F J

The most common form of systemic amyloidosis originates from antibody light chains. The large number of amino acid variations that distinguish amyloidogenic from nonamyloidogenic light chain proteins has impeded our understanding of the structural basis of light-chain fibril formation. Moreover, even among the subset of human light chains that are amyloidogenic, many primary structure differences are found. We compared the thermodynamic stabilities of two recombinant kappa4 light-chain variable domains (V(L)s) derived from amyloidogenic light chains with a V(L) from a benign light chain. The amyloidogenic V(L)s were significantly less stable than the benign V(L). Furthermore, only the amyloidogenic V(L)s formed fibrils under native conditions in an in vitro fibril formation assay. We used site-directed mutagenesis to examine the consequences of individual amino acid substitutions found in the amyloidogenic V(L)s on stability and fibril formation capability. Both stabilizing and destabilizing mutations were found; however, only destabilizing mutations induced fibril formation in vitro. We found that fibril formation by the benign V(L) could be induced by low concentrations of a denaturant. This indicates that there are no structural or sequence-specific features of the benign V(L) that are incompatible with fibril formation, other than its greater stability. These studies demonstrate that the V(L) beta-domain structure is vulnerable to destabilizing mutations at a number of sites, including complementarity determining regions (CDRs), and that loss of variable domain stability is a major driving force in fibril formation.

• Research Organization: Argonne National Laboratory (ANL)
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 938365
• Report Number(s): ANL/CMB/JA-29761
• Journal Information: Protein Sci., Journal Name: Protein Sci. Journal Issue: 3 ; Mar. 1999 Vol. 8
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
CHAINS
IMMUNOGLOBULINS
IN VITRO
MUTAGENESIS
MUTATIONS
PROTEINS
STABILITY
THERMODYNAMICS