Expression, purification and characterization of a synthetic gene encoding human amyloid β (Aβ1-42) in Escherichia coli

Abstract

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by a progressive loss of cognitive function. Existing evidence indicates that abnormal processing and extracellular deposition of the longer form of the amyloid peptide Aβ(1-42), a proteolytic derivative of the amyloid precursor protein (APP), is a key step in the pathogenesis of AD. Active immunization with Aβ(1-42) has been shown to decrease brain Aβ deposition and improve cognitive performance in mouse models of AD. In the present study, we sought to express the synthetic gene encoding Aβ in Escherichia coli to enable rapid production of the antigen and its purification. The synthetic gene has been constructed from six oligonucleotides by employing overlapping PCR strategy and expressed in E. coli using the T7 promoter system. The recombinant peptide has been purified to homogeneity by a single step Ni+2 affinity chromatography. Enzyme-linked immunosorbent assay (ELISA) using polyclonal anti-Aβ(1-42) sera confirms that the corresponding linear B-cell epitopic sequences are available for immunorecognition in the recombinant peptide. This methodology enables rapid, continuous production and purification in bulk amounts of human Aβ sequence by employing bacterial expression system