title: Immunoglobulin Light Chains Form an Extensive and Highly Ordered Fibril Involving the N- and C-Termini.
abstract: Light-chain (AL)-associated amyloidosis is a systemic disorder involving the formation and deposition of immunoglobulin AL fibrils in various bodily organs. One severe instance of AL disease is exhibited by the patient-derived variable domain (VL) of the light chain AL-09, a 108 amino acid residue protein containing seven mutations relative to the corresponding germline protein, κI O18/O8 VL. Previous work has demonstrated that the thermodynamic stability of native AL-09 VLis greatly lowered by two of these mutations, Y87H and N34I, whereas a third mutation, K42Q, further increases the kinetics of fibril formation. However, detailed knowledge regarding the residues that are responsible for stabilizing the misfolded fibril structure is lacking. In this study, using solid-state NMR spectroscopy, we show that the majority of the AL-09 VLsequence is immobilized in the fibrils and that the N- and C-terminal portions of the sequence are particularly well-structured. Thus, AL-09 VLforms an extensively ordered and β-strand-rich fibril structure. Furthermore, we demonstrate that the predominant β-sheet secondary structure and rigidity observed for in vitro prepared AL-09 VLfibrils are qualitatively similar to those observed for AL fibrils extracted from postmortem human spleen tissue, suggesting that this conformation may be representative of a common feature of AL fibrils.
authors.affiliation: Department of Biochemistry, Department of Chemistry, and Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign , 600 S Mathews Avenue, Urbana, Illinois 61801, United States.
authors.forename: Dennis W
authors.initials: DW
authors.lastname: Piehl
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic , 200 First Street SW, Rochester, Minnesota 55905, United States.
authors.forename: Luis M
authors.initials: LM
authors.lastname: Blancas-Mejía
authors.affiliation: Department of Medicine and Department of Radiology, University of Tennessee Graduate School of Medicine, 1924 Alcoa Hwy, Knoxville, Tennessee 37920, United States; Department of Medicine and Department of Radiology, University of Tennessee Graduate School of Medicine, 1924 Alcoa Hwy, Knoxville, Tennessee 37920, United States.
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Wall
authors.affiliation: Department of Medicine and Department of Radiology, University of Tennessee Graduate School of Medicine, 1924 Alcoa Hwy, Knoxville, Tennessee 37920, United States; Department of Medicine and Department of Radiology, University of Tennessee Graduate School of Medicine, 1924 Alcoa Hwy, Knoxville, Tennessee 37920, United States.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Kennel
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic , 200 First Street SW, Rochester, Minnesota 55905, United States.
authors.forename: Marina
authors.initials: M
authors.lastname: Ramirez-Alvarado
authors.affiliation: Department of Biochemistry, Department of Chemistry, and Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 600 S Mathews Avenue, Urbana, Illinois 61801, United States; Department of Biochemistry, Department of Chemistry, and Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 600 S Mathews Avenue, Urbana, Illinois 61801, United States; Department of Biochemistry, Department of Chemistry, and Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 600 S Mathews Avenue, Urbana, Illinois 61801, United States.
authors.forename: Chad M
authors.initials: CM
authors.lastname: Rienstra