An orthogonal system for heterologous expression of actinobacterial lasso peptides in Streptomyces hosts.

Lasso peptides are ribosomally synthesized and post-translationally modified peptides produced by bacteria. They are characterized by an unusual lariat-knot structure. Targeted genome scanning revealed a wide diversity of lasso peptides encoded in actinobacterial genomes, but cloning and heterologous expression of these clusters turned out to be problematic.

Halocin C8: an antimicrobial peptide distributed among four halophilic archaeal genera: Natrinema, Haloterrigena, Haloferax, and Halobacterium.

Halophilic archaea thrive in hypersaline ecosystems and produce antimicrobial peptides (AMPs) named halocins. AMPs are essential effectors of microbial interactions in natural ecosystems. Halocin C8 is a 7.

A hemocyanin-derived antimicrobial peptide from the penaeid shrimp adopts an alpha-helical structure that specifically permeabilizes fungal membranes.

Background: Hemocyanins are respiratory proteins with multiple functions. In diverse crustaceans hemocyanins can release histidine-rich antimicrobial peptides in response to microbial challenge. In penaeid shrimp, strictly antifungal peptides are released from the C-terminus of hemocyanins.

Characterization of Sviceucin from Streptomyces Provides Insight into Enzyme Exchangeability and Disulfide Bond Formation in Lasso Peptides.

Lasso peptides are bacterial ribosomally synthesized and post-translationally modified peptides. They have sparked increasing interest in peptide-based drug development because of their compact, interlocked structure, which offers superior stability and protein-binding capacity. Disulfide bond-containing lasso peptides are rare and exhibit highly sought-after activities.

Structural basis for hijacking siderophore receptors by antimicrobial lasso peptides.

The lasso peptide microcin J25 is known to hijack the siderophore receptor FhuA for initiating internalization. Here, we provide what is to our knowledge the first structural evidence on the recognition mechanism, and our biochemical data show that another closely related lasso peptide cannot interact with FhuA. Our work provides an explanation on the narrow activity spectrum of lasso peptides and opens the path to the development of new antibacterials.

Dissecting the maturation steps of the lasso peptide microcin J25 in vitro.

Microcin J25 is the archetype of a growing class of bacterial ribosomal peptides possessing a knotted topology (lasso peptides). It consists of an eight-residue macrolactam ring through which the C-terminal tail is threaded. It is biosynthesized as a precursor that is processed by two maturation enzymes (McjB/McjC).

Sequence determinants governing the topology and biological activity of a lasso peptide, microcin J25.

Microcin J25 is a potent antibacterial peptide produced by Escherichia coli AY25. It displays a lasso structure, which consists of a knot involving an N-terminal macrolactam ring through which the C-terminal tail is threaded and sterically trapped. In this study, we rationally designed and performed site-specific mutations in order to pinpoint the sequence determinants of the lasso topology.

Two enzymes catalyze the maturation of a lasso peptide in Escherichia coli.

Microcin J25 (MccJ25) is a gene-encoded lasso peptide secreted by Escherichia coli which exerts a potent antibacterial activity by blocking RNA polymerase. Here we demonstrate that McjB and McjC, encoded by genes in the MccJ25 gene cluster, catalyze the maturation of MccJ25. Requirement for both McjB and McjC was shown by gene inactivation and complementation assays.

The iron-siderophore transporter FhuA is the receptor for the antimicrobial peptide microcin J25: role of the microcin Val11-Pro16 beta-hairpin region in the recognition mechanism.

The role of the outer-membrane iron transporter FhuA as a potential receptor for the antimicrobial peptide MccJ25 (microcin J25) was studied through a series of in vivo and in vitro experiments. The requirement for both FhuA and the inner-membrane TonB-ExbB-ExbD complex was demonstrated by antibacterial assays using complementation of an fhuA(-) strain and by using isogenic strains mutated in genes encoding the protein complex respectively. In addition, MccJ25 was shown to block phage T5 infection of Escherichia coli, in vivo, by inhibiting phage adhesion, which suggested that MccJ25 prevents the interaction between the phage and its receptor FhuA.

Microcin J25, from the macrocyclic to the lasso structure: implications for biosynthetic, evolutionary and biotechnological perspectives.

Microcin J25 (MccJ25) is a cyclic antibacterial peptide secreted by a fecal isolate of Escherichia coli. It exerts highly potent activity on Salmonella and Escherichia species. The microcin is recognized at the outer membrane of sensitive strains by the FhuA multifunctional protein, which belongs to the iron/siderophore receptor family, and inhibits bacterial transcription through binding to the RNA-polymerase beta' subunit.

Siderophore peptide, a new type of post-translationally modified antibacterial peptide with potent activity.

Microcin E492 (MccE492, 7886 Da), the 84-amino acid antimicrobial peptide from Klebsiella pneumoniae, was purified in a post-translationally modified form, MccE492m (8717 Da), from culture supernatants of either the recombinant Escherichia coli VCS257 strain harboring the pJAM229 plasmid or the K. pneumoniae RYC492 strain. Chymotrypsin digestion of MccE492m led to the MccE492m-(74-84) C-terminal fragment that carries the modification and that was analyzed by mass spectrometry and nuclear magnetic resonance at natural abundance.

Microcin C51 plasmid genes: possible source of horizontal gene transfer.

Microcin C51 (MccC51) is an antimicrobial nucleotide-heptapeptide produced by a natural Escherichia coli strain. A 5.7-kb fragment of the pC51 plasmid carrying the genes involved in MccC51 production, secretion, and self-immunity was sequenced, and the genes were characterized.

Microcin E492 antibacterial activity: evidence for a TonB-dependent inner membrane permeabilization on Escherichia coli.

The mechanism of action of microcin E492 (MccE492) was investigated for the first time in live bacteria. MccE492 was expressed and purified to homogeneity through an optimized large-scale procedure. Highly purified MccE492 showed potent antibacterial activity at minimal inhibitory concentrations in the range of 0.

Thermolysin-linearized microcin J25 retains the structured core of the native macrocyclic peptide and displays antimicrobial activity.

Microcin J25 (MccJ25) is the single macrocyclic antimicrobial peptide belonging to the ribosomally synthesized class of microcins that are secreted by Enterobacteriaceae. It showed potent antibacterial activity against several Salmonella and Escherichia strains and exhibited a compact three-dimensional structure [Blond et al. (2001) Eur.

Identification of peptaibols from Trichoderma virens and cloning of a peptaibol synthetase.

The fungus Trichoderma virens is a ubiquitous soil saprophyte that has been applied as a biological control agent to protect plants from fungal pathogens. One mechanism of biocontrol is mycoparasitism, and T. virens produces antifungal compounds to assist in killing its fungal targets.

Combined use of LC/MS and a biological test for rapid identification of marine mycotoxins produced by Trichoderma koningii.

Trichoderma koningii Oudemans, a strain isolated from a shellfish farming area, was selected for its high frequency in samples and its ability to produce metabolites when cultured in natural seawater. Combined use of LC/MS and a biological test on blowfly larvae allowed the characterization of four compounds after purification in only two steps (VLC and HPLC). ESI/MS, a powerful tool for rapid identification and sequence determination of peptides, confirmed that these compounds were peptide, alpha-aminoisobutyric acid and amino alcohol (peptaibols), the usual metabolites of Trichoderma.