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Stabilizing an amyloidogenic λ6 light chain variable domain
Author(s) -
LunaMartínez Oscar D.,
HernándezSantoyo Alejandra,
VillalbaVelázquez Myriam I.,
SánchezAlcalá Rosalba,
FernándezVelasco Daniel A.,
Becerril Baltazar
Publication year - 2017
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.14265
Subject(s) - immunoglobulin light chain , mutant , mutation , fibril , crystallography , biophysics , chemistry , protein structure , gene , amyloidosis , chain (unit) , biology , antibody , biochemistry , genetics , physics , medicine , pathology , astronomy
Light chain amyloidosis is a lethal disease where vital organs are damaged by the fibrillar aggregation of monoclonal light chains. λ6a is an immunoglobulin light chain encoded by the germ‐line gene segment implicated in this disease. AR is a patient‐derived germ‐line variant with a markedly low thermodynamic stability and prone to form fibrils in vitro in less than an hour. Here, we sought to stabilize this domain by mutating some residues back to the germ‐line sequence, and the most stabilizing mutations were the single‐mutant AR ‐F21I and the double‐mutant AR ‐F21/ IV 104L, both located in the hydrophobic core. While mutation Arg25Gly in 6a JL 2 destabilized the domain, mutating Gly25 back to arginine in AR did not contribute to stabilization as expected. Crystallographic structures of AR and 6a‐R25G were generated to explain this discrepancy. Finally, 6a‐R25G crystals revealed an octameric assembly which was emulated into 6a JL 2 and AR crystals by replicating their structural parameters and suggesting a common assembly pattern. Database The atomic coordinates and structure factors have been deposited in the Protein Data Bank under the accession numbers 5IR3 and 5C9K .