Expression of human β-defensin-1 in recombinant Escherichia coli and analysis of its antimicrobial spectrum

Abstract

Escherichia coli BL21(DE3) was transformed with a pHCD1 plasmid harboring the human β-defensin-1 (hBD1) gene fused in frame behind a disulfide bond isomerase (DsbC), a His-tag, and an enterokinase cleavage site. After induction, the DsbC-hBD1 was expressed as a ~36 kDa soluble fusion protein in recombinant E. coli, which also inhibited host cell growth. After cell disruption, the soluble protein was easily recovered by Ni²⁺ affinity chromatography and cleaved by enterokinase to yield a mature hBD1 of about 4 kDa. Importantly, the mature hBD1 showed broad antimicrobial activity against Gram-positive and -negative pathogenic bacteria, including Streptococcus pneumoniae, E. coli O157:H7, and Klebsiella pneumoniae.

Key words: Antimicrobial activity, Escherichia coli, human β-defensin-1, soluble expression.