Identification of an antimicrobial peptide from human methionine sulfoxide reductase B3

Human methionine sulfoxide reductase B3A (hMsrB3A) is an endoplasmic reticulum (ER) reductase that catalyzes the stereospecific reduction of methionine-R-sulfoxide to methionine in proteins. In this work, we identified an antimicrobial peptide from hMsrB3A protein. The N-terminal ER-targeting signal peptide (amino acids 1-31) conferred an antimicrobial effect in Escherichia coli cells. Sequence and structural analyses showed that the overall positively charged ER signal peptide had an Arg- and Pro-rich region and a potential hydrophobic a-helical segment that contains 4 cysteine residues. The potential a-helical region was essential for the antimicrobial activity within E. coli cells. A synthetic peptide, comprised of 2-26 amino acids of the signal peptide, was effective at killing Gram-negative E. colt, Klebsiella pneumoniae, and Salmonella paratyphi, but had no bactericidal activity against Gram-positive Staphylococcus aureus. [BMB reports 2011; 44(10): 669-673]