Enterolysin A, a cell wall-degrading bacteriocin from Enterococcus faecalis LMG 2333.
A novel antimicrobial protein, designated enterolysin A, was purified from an Enterococcus faecalis LMG 2333 culture. Enterolysin A inhibits growth of selected enterococci, pediococci, lactococci, and lactobacilli. Antimicrobial activity was initially detected only on solid media, but by growing the bacteria in a fermentor under optimized production conditions (MRS broth with 4% [wt/vol] glucose, pH 6.5, and a temperature between 25 and 35 degrees C), the bacteriocin activity was increased to 5,120 bacteriocin units ml(-1). Enterolysin A production was regulated by pH, and activity was first detected in the transition between the logarithmic and stationary growth phases. Killing of sensitive bacteria by enterolysin A showed a dose-response behavior, and the bacteriocin has a bacteriolytic mode of action. Enterolysin A was purified, and the primary structure was determined by combined amino acid and DNA sequencing. This bacteriocin is translated as a 343-amino-acid preprotein with an sec-dependent signal peptide of 27 amino acids, which is followed by a sequence corresponding to the N-terminal part of the purified protein. Mature enterolysin A consists of 316 amino acids and has a calculated molecular weight of 34,501, and the theoretical pI is 9.24. The N terminus of enterolysin A is homologous to the catalytic domains of different cell wall-degrading proteins with modular structures. These include lysostaphin, ALE-1, zoocin A, and LytM, which are all endopeptidases belonging to the M37 protease family. The N-terminal part of enterolysin A is linked by a threonine-proline-rich region to a putative C-terminal recognition domain, which shows significant sequence identity to two bacteriophage lysins.
Laboratory of Microbial Gene Technology, Agricultural University of Norway, N-1432 As, Norway. tnilsen@partners.org
Trine
T
Nilsen
Ingolf F
IF
Nes
Helge
H
Holo
D000595:Amino Acid Sequence; D001430:Bacteriocins / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification* / Q000494:pharmacology*; D001483:Base Sequence; D002473:Cell Wall / Q000187:drug effects; D004269:DNA, Bacterial / Q000235:genetics; D004355:Drug Stability; D013293:Enterococcus faecalis / Q000737:chemistry* / Q000235:genetics; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006358:Hot Temperature; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid
D001430:Bacteriocins; D004269:DNA, Bacterial