Beschreibung:
<jats:title>ABSTRACT</jats:title>
<jats:p>
Lantibiotics, such as nisin and subtilin, are lanthionine-containing peptides that exhibit antimicrobial as well as pheromone-like autoinducing activity. Autoinduction is specific for each lantibiotic, and reporter systems for nisin and subtilin autoinduction are available. In this report, we used the previously reported subtilin autoinduction bioassay in combination with mass spectrometric analyses to identify the novel subtilin-like lantibiotic entianin from
<jats:italic>Bacillus subtilis</jats:italic>
subsp.
<jats:italic>spizizenii</jats:italic>
DSM 15029
<jats:sup>T</jats:sup>
. Linearization of entianin using Raney nickel-catalyzed reductive cleavage enabled, for the first time, the use of tandem mass spectrometry for the fast and efficient determination of an entire lantibiotic primary structure, including posttranslational modifications. The amino acid sequence determined was verified by DNA sequencing of the
<jats:italic>etnS</jats:italic>
structural gene, which confirmed that entianin differs from subtilin at 3 amino acid positions. In contrast to
<jats:italic>B. subtilis</jats:italic>
ATCC 6633, which produces only small amounts of unsuccinylated subtilin,
<jats:italic>B. subtilis</jats:italic>
DSM 15029
<jats:sup>T</jats:sup>
secretes considerable amounts of unsuccinylated entianin. Entianin was very active against several Gram-positive pathogens, such as
<jats:italic>Staphylococcus aureus</jats:italic>
and
<jats:italic>Enterococcus faecalis.</jats:italic>
The growth-inhibiting activity of succinylated entianin (S-entianin) was much lower than that of unsuccinylated entianin: a 40-fold higher concentration was required for inhibition. For succinylated subtilin (S-subtilin), a concentration 100-fold higher than that of unsuccinylated entianin was required to inhibit the growth of a
<jats:italic>B. subtilis</jats:italic>
test strain. This finding was in accordance with a strongly reduced sensing of cellular envelope stress provided by S-entianin relative to that of entianin. Remarkably, S-entianin and S-subtilin showed considerable autoinduction activity, clearly demonstrating that autoinduction and antibiotic activity underlie different molecular mechanisms.
</jats:p>