Abstract
Drosophila melanogaster GTPase protein, Beck, was a 22kDa protein with 185 amino acids which was found in the mushroom of body brain. The Beck protein belongs to Rab family (Ras like protein in brain) and haves approximately 35%~78% sequence identities with other Rab family members. The Rab family proteins were reported to participate in cellular processes, such as facilitating vesicle formation and protein vesicle trafficking. Rab family protein were associated with neurodegenerative disease, for example, Parkinson’s disease-associated defects in Rab family protein, RAB7L1. In this study, we observed that Beck went through α-helical conformational to β-strand induced by thermal process and further form the amyloid-like β-aggregate which bind to specific dye, thioflavin-T and Congo red. The amyloid-like fibrils were centrifuged with sucrose and studied by using transmission electron microscopy. In addition, the free form of Beck shows protein aggregation and assembly into higher order, while GTP-bound form of Beck enhanced the correct folding and stability of monomer. Our studies of the Beck protein conformational change and formation of amyloid-like β-aggregate formation may contribute to the understanding of neurodegenerative diseases in Rab family proteins.