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Flinspach K.,University of Tubingen | Flinspach K.,German Center for Infection Research | Kapitzke C.,University of Tubingen | Tocchetti A.,KtedoGen Srl | And 4 more authors.
PLoS ONE | Year: 2014

GE2270 is a thiopeptide antibiotic generated by extensive posttranslational modifications of a ribosomally generated precursor peptide. Thiopeptides are especially active against Gram-positive bacteria, including methicillin resistant Staphylococcus aureus (MRSA). In this study the GE2270 biosynthetic gene cluster (pbt) from Planobispora rosea ATCC 53733 was successfully expressed in the heterologous host strain Streptomyces coelicolor M1146. Notably, exconjugants containing the pbt gene cluster could only be obtained after deletion of the major part of the ribosomal genes flanking the gene cluster. This is a striking example that genes belonging to primary metabolism can prevent the successful conjugative transfer of DNA from phylogenetic distant species and thus complicate heterologous expression of secondary metabolite gene clusters. GE2270 production in the heterologous producer strain increased after introduction of the constitutive ermE*promoter upstream of the GE2270 resistance gene tuf from P. rosea. Insertion of the inducible tcp830 promoter resulted in inducible GE2270 production. When the regulatory gene pbtR was deleted, the resulting strain ceased to produce GE2270, suggesting an essential role of PbtR as a putative transcriptional activator of GE2270 expression. © 2014 Flinspach et al.

Naicons Srl | Date: 2013-11-27

The present invention concerns novel antibiotic compounds, which are lantibiotics, the processes for their preparation, their pharmaceutically acceptable salts, pharmaceutical compositions containing the lantibiotics, and their use as antibacterial agents. Compounds designated as lantibiotics, such as those of the present invention, are peptides belonging to the general class of antibiotic compounds, and are further generally characterized by the presence of the amino acids lanthionine and/or 3-methyllanthionine. The novel lantibiotic compounds are active against bacterial infections caused by

Zhang Y.,Rutgers University | Degen D.,Rutgers University | Ho M.X.,Rutgers University | Sineva E.,Rutgers University | And 13 more authors.
eLife | Year: 2014

Using a combination of genetic, biochemical, and structural approaches, we show that the cyclic-peptide antibiotic GE23077 (GE) binds directly to the bacterial RNA polymerase (RNAP) active-center 'i' and 'i+1' nucleotide binding sites, preventing the binding of initiating nucleotides, and thereby preventing transcription initiation. The target-based resistance spectrum for GE is unusually small, reflecting the fact that the GE binding site on RNAP includes residues of the RNAP active center that cannot be substituted without loss of RNAP activity. The GE binding site on RNAP is different from the rifamycin binding site. Accordingly, GE and rifamycins do not exhibit cross-resistance, and GE and a rifamycin can bind simultaneously to RNAP. The GE binding site on RNAP is immediately adjacent to the rifamycin binding site. Accordingly, covalent linkage of GE to a rifamycin provides a bipartite inhibitor having very high potency and very low susceptibility to target-based resistance. © Zhang et al.

Ortega M.A.,University of Illinois at Urbana - Champaign | Hao Y.,University of Illinois at Urbana - Champaign | Walker M.C.,University of Illinois at Urbana - Champaign | Donadio S.,Naicons Srl | And 3 more authors.
Cell Chemical Biology | Year: 2016

Class I lantibiotic dehydratases dehydrate selected Ser/Thr residues of a precursor peptide. Recent studies demonstrated the requirement of glutamyl-tRNAGlu for Ser/Thr activation by one of these enzymes (NisB) from the Firmicute Lactococcus lactis. However, the generality of glutamyl-tRNAGlu usage and the tRNA specificity of lantibiotic dehydratases have not been established. Here we report the 2.7-Å resolution crystal structure, along with the glutamyl-tRNAGlu utilization of MibB, a lantibiotic dehydratase from the Actinobacterium Microbispora sp. 107891 involved in the biosynthesis of the clinical candidate NAI-107. Biochemical assays revealed nucleotides A73 and U72 within the tRNAGlu acceptor stem to be important for MibB glutamyl-tRNAGlu usage. Using this knowledge, an expression system for the production of NAI-107 analogs in Escherichia coli was developed, overcoming the inability of MibB to utilize E. coli tRNAGlu. Our work provides evidence for a common tRNAGlu-dependent dehydration mechanism, paving the way for the characterization of lantibiotics from various phyla. © 2016 Elsevier Ltd. All rights reserved.

Maffioli S.I.,Naicons Srl | Maffioli S.I.,KtedoGen Srl | Monciardini P.,Naicons Srl | Monciardini P.,KtedoGen Srl | And 9 more authors.
ACS Chemical Biology | Year: 2015

Lantibiotics, an abbreviation for "lanthionine-containing antibiotics", interfere with bacterial metabolism by a mechanism not exploited by the antibiotics currently in clinical use. Thus, they have aroused interest as a source for new therapeutic agents because they can overcome existing resistance mechanisms. Starting from fermentation broth extracts preselected from a high-throughput screening program for discovering cell-wall inhibitors, we isolated a series of related class I lantibiotics produced by different genera of actinomycetes. Analytical techniques together with explorative chemistry have been used to establish their structures: the newly described compounds share a common 24 aa sequence with the previously reported lantibiotic planosporicin (aka 97518), differing at positions 4, 6, and 14. All of these compounds maintain an overall -1 charge at physiological pH. While all of these lantibiotics display modest antibacterial activity, their potency can be substantially modulated by progressively eliminating the negative charges, with the most active compounds carrying basic amide derivatives of the two carboxylates originally present in the natural compounds. Interestingly, both natural and chemically modified lantibiotics target the key biosynthetic intermediate lipid II, but the former compounds do not bind as effectively as the latter in vivo. Remarkably, the basic derivatives display an antibacterial potency and a killing effect similar to those of NAI-107, a distantly related actinomycete-produced class I lantibiotic which lacks altogether carboxyl groups and which is a promising clinical candidate for treating Gram-positive infections caused by multi-drug-resistant pathogens. © 2015 American Chemical Society.

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