Human RAD51 Protein Forms Amyloid-like Aggregates In Vitro

Abstract

RAD51 is a central protein of homologous recombination and DNA repair processes that maintains genome stability and ensures the accurate repair of double-stranded breaks (DSBs). In this work, we assessed amyloid properties of RAD51 in vitro and in the bacterial curli-dependent amyloid generator (C-DAG) system. Resistance to ionic detergents, staining with amyloid-specific dyes, polarized microscopy, transmission electron microscopy (TEM), X-ray diffraction and other methods were used to evaluate the properties and structure of RAD51 aggregates. The purified human RAD51 protein formed detergent-resistant aggregates in vitro that had an unbranched cross-β fibrillar structure, which is typical for amyloids, and were stained with amyloid-specific dyes. Congo-red-stained RAD51 aggregates demonstrated birefringence under polarized light. RAD51 fibrils produced sharp circular X-ray reflections at 4.7 Å and 10 Å, demonstrating that they had a cross-β structure. Cytoplasmic aggregates of RAD51 were observed in cell cultures overexpressing RAD51. We demonstrated that a key protein that maintains genome stability, RAD51, has amyloid properties in vitro and in the C-DAG system and discussed the possible biological relevance of this observation.

Noninvasive Diagnostics of Renal Amyloidosis: Current State and Perspectives

“…Each protofilament has a cross-β structure, where β-strands are stacked perpendicular to the fibril axis [ 6 ]. Amyloids usually bind specific dyes, such as Thioflavin T (ThT) and Congo red [ 7 , 8 , 9 ], and exhibit resistance against the actions of proteases and various detergents [ 10 , 11 ]. The amyloidogenic properties may be a consequence of variations in the amino acid sequence and are manifested in different pathologies associated with increased levels of amyloidogenic protein [ 1 , 12 , 13 , 14 ].…”

Overview of the Special Issue “Protein-Based Infection, Inheritance, and Memory”

“…The experimental paper by Kachkin et al [22] describes the identification of a new human protein with amyloid properties, RAD51, that is a central player in DNA recombination and repair. While RAD51 is known to form a functional filamentous structure, this work points to its ability to produce typical cross-β amyloid fibrils as well.…”