The stability and aggregation of human LECT2 protein

Date
2023
DOI
Authors
Dang, Dylan
Version
OA Version
Citation
Abstract
BACKGROUND: Amyloidosis is a collection of diseases that involve protein misfolding and aggregation. Recently a new type of amyloidosis was classified that involved the aggregation of the leukocyte cell-derived chemotaxin-2 (LECT2) protein in an amyloid fibril form (ALECT2). Because this disease was found to disproportionately affect Hispanic populations, various factors are being explored as to pinpoint a cause for the condition. Patients diagnosed with ALECT2 amyloidosis often produce a variant of LECT2 that contains a valine residue at position 40 of the protein rather than an isoleucine residue. We hypothesized this would increase the propensity of ALECT2 formation by altering protein stability. Another factor to consider is zinc loss as a zinc ion is coordinated by multiple amino acid residues in the protein, which implies a potential detrimental effect of zinc loss on LECT2 stability. OBJECTIVE: To determine whether there is a difference between the stability of the V40 and I40 variants of LECT2 that could increase the propensity of LECT2 aggregation into amyloid plaques and development and progression into LECT2 amyloidosis. METHODS: The recombinant V40 and I40 variants of the LECT2 were grown in both E. coli and human embryonic kidney cells (HEK cells). Purified proteins were then subjected to urea denaturation and amyloid formation assays. RESULTS: Both LECT2 variants were successfully cloned, expressed, and purified. Urea denaturation revealed similar stability of both proteins and removal of Zn2+ destabilized both variants to the same extent. The variants aggregate readily at pH 8 and aggregation was accelerated after Zn2+ removal. CONCLUSIONS: We noted overall similar stabilities for LECT2 I40 and V40, with only mild variations in stability and aggregation. Although LECT2 V40 is associated with ALECT2 amyloidosis, the variations in stability and aggregation in vitro are not strong evidence that this polymorphism destabilizes LECT2. Additionally, we observed a destabilizing effect in LECT2 variants without zinc, drawing more attention to the larger role of zinc in ALECT2 amyloidosis. Further studies are required before a more definitive conclusion can be drawn.
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