title: Influence of the germline sequence on the thermodynamic stability and fibrillogenicity of human lambda 6 light chains.
abstract: Light chain-associated amyloidosis is a fatal disease characterized by the aggregation and pathologic deposition of monoclonal light chain-related fragments as amyloid fibrils in organs or tissues throughout the body. Notably, it has been observed that proteins encoded by the lambda variable light chain (V(L)) gene segment 6a are invariably associated with amyloid deposition; however, the contribution of the gene to this phenomenon has not been established. In this regard, we have determined the thermodynamic stability and kinetics of in vitro fibrillogenesis of a recombinant (r) V(L) protein, designated 6aJL2, which contains the predicted sequences encoded by the 6a and JL2 germline genes. Additionally, we studied a 6a mutant (6aJL2-Arg25Gly), that is present in approximately 25% of all amyloid-associated lambda6 light chains. Remarkably, the wild-type 6aJL2 protein was more stable than were all known amyloidogenic kappa and lambda light chains for which stability parameters are available; more importantly, it was even more so (and less fibrillogenic) than the only clinically proven nonamyloidogenic lambda6 protein, Jto. Conversely, the mutated 6aJL2-R25G molecule was considerably less stable and more fibrillogenic than was the native 6aJL2. Our data indicate that the propensity of lambda6 light chains to form amyloid can not be attributed to thermodynamic instability of the germline-encoded Vlambda6 domain, but rather, is dependent on sequence alterations that render such proteins amyloidogenic.
authors.affiliation: Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, Morelos, México.
authors.forename: Luis
authors.initials: L
authors.lastname: del Pozo Yauner
authors.forename: Ernesto
authors.initials: E
authors.lastname: Ortiz
authors.forename: Rosalba
authors.initials: R
authors.lastname: Sánchez
authors.forename: Rosana
authors.initials: R
authors.lastname: Sánchez-López
authors.forename: Leopoldo
authors.initials: L
authors.lastname: Güereca
authors.forename: Charles L
authors.initials: CL
authors.lastname: Murphy
authors.forename: Amy
authors.initials: A
authors.lastname: Allen
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Wall
authors.forename: D Alejandro
authors.initials: DA
authors.lastname: Fernández-Velasco
authors.forename: Alan
authors.initials: A
authors.lastname: Solomon
authors.forename: Baltazar
authors.initials: B
authors.lastname: Becerril
mesh_terms: D002851:Chromatography, High Pressure Liquid; D018360:Crystallography, X-Ray; D004591:Electrophoresis, Polyacrylamide Gel; D005854:Germ Cells; D006801:Humans; D007146:Immunoglobulin lambda-Chains / Q000737:chemistry* / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D013057:Spectrum Analysis / Q000379:methods; D013816:Thermodynamics
chemical_list: D007146:Immunoglobulin lambda-Chains