Wild type beta-2 microglobulin and DE loop mutants display a common fibrillar architecture

Area of Science:

• Biochemistry
• Structural Biology
• Protein Misfolding Diseases

Background:

• Beta-2 microglobulin (β2m) is implicated in dialysis-related amyloidosis.
• The DE loop of β2m is crucial for protein stability and amyloid formation.
• Previous studies link DE loop strain to β2m aggregation, but aggregate similarity remained unaddressed.

Purpose of the Study:

• To investigate if wild-type (wt) β2m and DE loop mutants form similar aggregates.
• To determine the structural characteristics of aggregates formed by wt and mutated β2m.
• To elucidate the role of DE loop mutations in β2m aggregation pathways.

Main Methods:

• Atomic force microscopy (AFM) for aggregate morphology.
• Infrared spectroscopy for structural organization analysis.
• Comparative analysis of wild-type and DE loop mutant β2m fibrillar samples.

Main Results:

• DE loop mutants formed aggregates morphologically and structurally similar to wild-type β2m.
• No evidence suggests mutations open entirely new aggregation pathways.
• The primary impact of DE loop mutations appears to be altered native fold stability.

Conclusions:

• The structural organization of β2m aggregates is conserved across DE loop mutants and wild-type protein.
• Differences in aggregation propensity are mainly attributed to variations in native protein stability.
• The DE loop's role in monomeric β2m structure and its function within the Major Histocompatibility Complex warrants further consideration.