Identification, Characterization, and Three-Dimensional Structure of the Novel Circular Bacteriocin, Enterocin NKR-5-3B, from Enterococcus faecium.

Enterocin NKR-5-3B, one of the multiple bacteriodns produced by Enterococcus faecium NKR-5-3, is a 64-amino add novel drcular bacteriocin that displays broad-spectrum antimicrobial activity. Here we report the identification, characterization, and three-dimensional nuclear magnetic resonance solution structure determination of enterocin NKR-5-3B. Enterodn NKR-5-3B is characterized by four helical segments that enclose a compact hydrophobic core, which together with its circular backbone impart high stability and structural integrity. We also report the corresponding structural gene, enkB, that encodes an 87-amino add precursor peptide that undergoes a yet to be described enzymatic processing that involves adjacent cleavage and ligation of Leu24 and Trp87 to yield the mature (drcular) enterocin NKR-5-3B. [ABSTRACT FROM AUTHOR]