PMID: 28898537
Luna-Martinez OD, Hernandez-Santoyo A, Villalba-Velazquez MI, Sanchez-Alcala R, Fernandez-Velasco DA, Becerril B
Stabilizing an amyloidogenic lambda6 light chain variable domain.
FEBS J. 2017 Sep 12. doi: 10.1111/febs.14265.
Light chain amyloidosis is a lethal disease where vital organs are damaged by the fibrillar aggregation of monoclonal light chains. lambda6a 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/IV104L, both located in the hydrophobic core. While mutation Arg25Gly in 6aJL2 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 6aJL2 and AR crystals by replicating their structural parameters and suggesting a common assembly pattern. This article is protected by copyright. All rights reserved.