Restoration of Bioactive Lantibiotic Suicin from a Remnant lan Locus of Pathogenic Streptococcus suis Serotype 2

Abstract

cLantibiotics are ribosomally synthesized, posttranslationally modified antimicrobial peptides. Their biosynthesis genes are usually organized in gene clusters, which are mainly found in Gram-positive bacteria, including pathogenic streptococci. Three highly virulent Streptococcus suis serotype 2 strains (98HAH33, 05ZYH33, and SC84) have been shown to contain an 89K pathogenicity island. Here, on these islands, we unveiled and reannotated a putative lantibiotic locus designated sui which contains a virulence-associated two-component regulator, suiK-suiR. In silico analysis revealed that the putative lantibiotic modification gene suiM was interrupted by a 7.9-kb integron and that other biosynthesis-related genes contained various frameshift mutations. By reconstituting the intact suiM in Escherichia coli together with a semi-in vitro biosynthesis system, a putative lantibiotic named suicin was produced with bactericidal activities against a variety of Gram-positive strains, including pathogenic streptococci and vancomycin-resistant enterococci. Ring topology dissection indicated that the 34-amino-acid lantibiotic contained two methyllanthionine residues and one disulfide bridge, which render suicin in an N-terminal linear and C-terminal globular shape. To confirm the function of suiK-suiR, SuiR was overexpressed and purified. In vitro analysis showed that SuiR could specifically bind to the suiA gene promoter. Its coexpression with suiK could activate suiA gene promoter in Lactococcus lactis NZ9000. Conclusively, we obtained a novel lantibiotic suicin by restoring its production from the remnant sui locus and demonstrated that virulence-associated SuiK-SuiR regulates its production.

Suicin 90-1330 from a Nonvirulent Strain of Streptococcus suis: a Nisin-Related Lantibiotic Active on Gram-Positive Swine Pathogens

“…The suicin 90-1330 locus contains all of the genes present in the nisin U locus in a similar arrangement. Recently, Wang et al (30) identified a putative lantibiotic locus containing nine genes in highly virulent serotype strains. However, no bacteriocin activity could be detected because the putative lantibiotic modification gene (suiM) was interrupted through insertion of a 7.9-kb integron, while other biosynthesis-related genes contained various frameshift mutations.…”

Bovicin HJ50-Like Lantibiotics, a Novel Subgroup of Lantibiotics Featured by an Indispensable Disulfide Bridge

“…Recently, we have biosynthesized one bovicin HJ50-like lantibiotic suicin from a remnant sui locus via a semi- in vitro biosynthesis (SIVB) system by reconstitution of the disrupted modification gene suiM in Escherichia coli and subsequent in vitro digestion with peptidase domain of SuiT [14], [17]. In this study, three other bovicin HJ50-like lantibiotics named perecin, cerecin and thuricin were obtained and characterized, which were all novel lantibotics from separate species.…”

One-pot synthesis of class II lanthipeptide bovicin HJ50 via an engineered lanthipeptide synthetase

“…Precursor hexahistidine-tagged BovA (His 6 -BovA) was expressed and purified from inclusion bodies by IMAC and C18 reversed phase high performance liquid chromatography (RP-HPLC) as described previously26. When incubating His 6 -BovA (20 μM) and BovT150M (2 μM) in assay buffer containing 10 mM Mg 2+ , 1 mM DL-dithiothreitol (DTT) and 2.5 mM adenosine triphosphate (ATP) for 1 h, bioactive bovicin HJ50 was produced (Fig.…”

“…Suicin was a bovicin HJ50-like lanthipeptide restored from a remnant lan locus of S. suis serotype 2 and lacticin 481 was a typical class II lanthipeptide with no disulfide bridge26. The chimeric peptide His 6 -BovsuiA consisting of BovA leader peptide and suicin core peptide was purified and incubated with BovT150M.…”