Effect of lysine modification on the stability and cellular binding of human amyloidogenic light chains.
AL amyloidosis is characterized by the pathologic deposition as fibrils of monoclonal light chains (i.e., Bence Jones proteins [BJPs]) in particular organs and tissues. This phenomenon has been attributed to the presence in amyloidogenic proteins of particular amino acids that cause these molecules to become unstable, as well as post-translational modifications and, in regard to the latter, we have investigated the effect of biotinylation of lysyl residues on cell binding. We utilized an experimental system designed to test if BJPs obtained from patients with AL amyloidosis or, as a control, multiple myeloma (MM), bound human fibroblasts and renal epithelial cells. As documented by fluorescence microscopy and ELISA, the amyloidogenic BJPs, as compared with MM components, bound preferentially and this reactivity increased significantly after chemical modification of their lysyl residues with sulfo-NHS-biotin. Further, based on tryptophan fluorescence and circular dichroism data, it was apparent that their conformation was altered, which we hypothesize exposed a binding site not accessible on the native protein. The results of our studies indicate that post-translational structural modifications of pathologic light chains can enhance their capacity for cellular interaction and thus may contribute to the pathogenesis of AL amyloidosis and multiple myeloma.
Davern
S
S
Human Immunology and Cancer Program, Department of Medicine, University of Tennessee Graduate School of Medicine, 1924 Alcoa Hwy, Knoxville, TN 37920, USA. davernsm@ornl.gov
Murphy
C L
CL
O'Neill
H
H
Wall
J S
JS
Weiss
D T
DT
Solomon
A
A
D000595:Amino Acid Sequence; D000686:Amyloidosis / Q000276:immunology / Q000378:metabolism / Q000652:urine; D001536:Bence Jones Protein / Q000737:chemistry* / Q000378:metabolism; D019921:Biotinylation; D002460:Cell Line; D002478:Cells, Cultured; D002853:Chromatography, Liquid; D002942:Circular Dichroism; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000075363:Immunoglobulin Light-chain Amyloidosis; D008239:Lysine / Q000737:chemistry* / Q000378:metabolism; D008297:Male; D013058:Mass Spectrometry; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009101:Multiple Myeloma / Q000276:immunology / Q000378:metabolism / Q000652:urine; D011485:Protein Binding; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D013816:Thermodynamics
D007147:Immunoglobulin Light Chains; D001536:Bence Jones Protein; D008239:Lysine