Sonorensin: an Antimicrobial Peptide, Belonging to the Heterocycloanthracin Subfamily of Bacteriocins, from a New Marine Isolate, Bacillus sonorensis MT93

Abstract

Marine environments are the greatest fronts of biodiversity, representing a resource of unexploited or unknown microorganisms and new substances having potential applications. Among microbial products, antimicrobial peptides (AMPs) have received great attention recently due to their applications as food preservatives and therapeutic agents. A new marine soil isolate producing an AMP was identified as Bacillus sonorensis based on 16S rRNA gene sequence analysis. It produced an AMP that showed a broad spectrum of activity against both Gram-positive and Gram-negative bacteria. The peptide, named sonorensin, was purified to homogeneity using a combination of chromatographic techniques. The intact molecular mass of the purified peptide, 6,274 Da, as revealed by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF), was in agreement with Tricine-SDS-PAGE analysis. A PCR array of primers was used to identify AMP structural genes, which allowed the successful amplification of the related genes from strain MT93. The putative open reading frame of sonorensin was amplified, cloned into the pET-32a(؉) vector, expressed as a thioredoxin (Trx) fusion protein in Escherichia coli, and then purified. Sequence alignment analysis revealed that the bacteriocin being reported could belong to new subfamily of bacteriocins, heterocycloanthracin. The peptide indicated its potential as a biocontrol agent or food antimicrobial agent, due to its antimicrobial activity against bacteria such as Listeria monocytogenes and Staphylococcus aureus. This is the first report of the production, purification, and characterization of wild-type and recombinant bacteriocin by B. sonorensis and the first bacteriocin of the heterocycloanthracin subfamily to be characterized.

YcaO-Dependent Posttranslational Amide Activation: Biosynthesis, Structure, and Function

“…This proposed cleavage site, if correct, would be highly unusual. 189 Recombinant expression of only the proposed sonorensin core peptide, in the absence of any modifying enzymes, resulted in a peptide with anti- Listeria activity, an observation that led to the conclusion there is no modification of the natural product. 189 However, until further studies including high-resolution mass spectrometry, NMR, and biochemical testing, the actual structure of sonorensin and whether it belongs among azol(in)e-containing RiPPs remains uncertain.…”

Identification of an Auxiliary Leader Peptide-Binding Protein Required for Azoline Formation in Ribosomal Natural Products

“…6,7 Recently, the first report regarding the isolation of a HCA natural product has emerged; 8 however, the structure of the compound was not described. Here we report the reconstitution of the fused TOMM cyclodehydratase from the Bacillus sp.…”

Pseudomycoicidin, a Class II Lantibiotic from Bacillus pseudomycoides

“…1B). Such motifs also are found in the heterocycloanthracins, a new subgroup of thiazole-containing bacteriocins (30), and have not yet been observed in lantibiotics; the first member of the heterocycloanthracin group, sonorensin from Bacillus sonorensis MT93, contains five repeated SCWSC motifs and has been purified recently (29).…”

“…In the present study, we performed a database search for new lantibiotic gene clusters using the biosynthetic enzyme of the class II lantibiotic mersacidin MrsM (27). This search identified a putative lantibi-otic biosynthetic gene cluster in Bacillus pseudomycoides DSM 12442 (28) with a core peptide of a very intriguing structure, resembling that of a lantibiotic in its N-terminal part and reminiscent of a putative heterocycloanthracin, a recently identified subgroup of bacteriocins, in its C-terminal domain (29,30). In this study, we report the successful heterologous production and characterization of the novel lantibiotic, which we have termed pseudomycoicidin, in E. coli.…”