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Structure-Activity Relationships of the S-Linked Glycocin Sublancin.

ABSTRACT: Sublancin is a 37-amino acid antimicrobial peptide belonging to the glycocin family of natural products. It contains two helices that are held together by two disulfide bonds as well as an unusual S-glucosidic linkage to a Cys in a loop connecting the helices. We report the reconstitution of the biosynthetic pathway to this natural product in Escherichia coli. This technology enabled the evaluation of the structure-activity relationships of the solvent-exposed residues in the helices. The biosynthetic machinery proved tolerant of changes in both helices, and the bioactivity studies of the resulting mutants show that two residues in helix B are important for bioactivity, Asn31 and Arg33.

SUBMITTER: Biswas S

PROVIDER: S-EPMC5732038 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

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Structure-Activity Relationships of the S-Linked Glycocin Sublancin.

Biswas Subhanip S Garcia De Gonzalo Chantal V CV Repka Lindsay M LM van der Donk Wilfred A WA

ACS chemical biology 20171110 12

Sublancin is a 37-amino acid antimicrobial peptide belonging to the glycocin family of natural products. It contains two helices that are held together by two disulfide bonds as well as an unusual S-glucosidic linkage to a Cys in a loop connecting the helices. We report the reconstitution of the biosynthetic pathway to this natural product in Escherichia coli. This technology enabled the evaluation of the structure-activity relationships of the solvent-exposed residues in the helices. The biosyn ...[more]

PMID: 29112373

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NMR structure of the S-linked glycopeptide sublancin 168.

Project description:Sublancin 168 is a member of a small group of glycosylated antimicrobial peptides known as glycocins. The solution structure of sublancin 168, a 37-amino-acid peptide produced by Bacillus subtilis 168, has been solved by nuclear magnetic resonance (NMR) spectroscopy. Sublancin comprises two α-helices and a well-defined interhelical loop. The two helices span residues 6-16 and 26-35, and the loop region encompasses residues 17-25. The 9-amino-acid loop region contains a β-S-linked glucose moiety attached to Cys22. Hydrophobic interactions as well as hydrogen bonding are responsible for the well-structured loop region. The three-dimensional structure provides an explanation for the previously reported extraordinary high stability of sublancin 168.

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Structure-Activity Relationships of ENMs

Project description:Current nano-SARs are often based on univariate assessments and fail to provide tiered views on ENM-induced bio-effects. Here we pioneered a multi-hierarchical nano-SAR assessment for a representative ENM, Fe2O3, by metabolomics and proteomics analyses. The established nano-SAR profile allows visualizing the contributions of 7 basic properties of Fe2O3 to its diverse bio-effects. For instance, while surface reactivity is responsible for Fe2O3-induced cell migration, the inflammatory effects of Fe2O3 are determined by aspect ratio (nanorods) or surface reactivity (nanoplates). These nano-SARs were examined in THP-1 cells and animal lungs, which allowed us to decipher the detailed mechanisms including NLRP3 inflammasome pathway and monocyte chemoattractant protein-1 dependent signaling. This study provides new insights for nano-SARs, which may facilitate the tailored design of ENMs to endow them with desired bio-effects.

2019-11-12 | PXD010614 | Pride

Sublancin is not a lantibiotic but an S-linked glycopeptide.

Project description:Sublancin is shown to be an S-linked glycopeptide containing a glucose attached to a cysteine residue, establishing a new post-translational modification. The activity of the S-glycosyl transferase was reconstituted in vitro, and the enzyme is shown to have relaxed substrate specificity, allowing the preparation of analogs of sublancin. Glycosylation is essential for its antimicrobial activity.

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QnrS1 structure-activity relationships.

Project description:ObjectivesLoop B is important for low-level quinolone resistance conferred by Qnr proteins. The role of individual amino acids within QnrS1 loop B in quinolone resistance and gyrase protection was assessed.MethodsqnrS1 and 11 qnrS1 alleles with site-directed Ala mutations in loop B were expressed in Escherichia coli BL21(DE3) and proteins were purified by affinity chromatography. Ciprofloxacin MICs were determined with and without IPTG. Gyrase DNA supercoiling was measured with and without ciprofloxacin IC50 and with various concentrations of QnrS1 proteins.ResultsWild-type QnrS1 and QnrS1 with Asn-110→Ala and Arg-111→Ala substitutions increased the ciprofloxacin MIC 12-fold in BL21(DE3), although QnrS1 with Gln-107→Ala replacement increased it 2-fold more than wild-type did. However, QnrS1 with Ala substitutions at His-106, Val-108, Ser-109, Met-112, Tyr-113, Phe-114, Cys-115 and Ser-116 increased ciprofloxacin MIC 1.4- to 8-fold less than wild-type QnrS1. Induction by 10-1000 μM IPTG increased ciprofloxacin MICs for all mutants, reaching values similar to those for wild-type. Purified wild-type and mutated proteins differed in protection of gyrase from ciprofloxacin action. Wild-type QnrS1 produced complete protection of gyrase supercoiling from ciprofloxacin (1.8 μM) action at 0.05 nM and half protection at 0.5 pM, whereas QnrS1 with Ala replacements that conferred the least increase in ciprofloxacin MICs also required the highest QnrS1 concentrations for protection.ConclusionsKey individual residues in QnrS1 loop B affect ciprofloxacin resistance and gyrase protection from ciprofloxacin action, supporting the concept that loop B is key for interaction with gyrase necessary for quinolone resistance.

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Total chemical synthesis of glycocin F and analogues: S-glycosylation confers improved antimicrobial activity.

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