The lantibiotic-synthesizing flavoprotein EpiD catalyzes the oxidative decarboxylation of peptidylcysteines to peptidyl-aminoenethiols. The sequence motif responsible for flavin coenzyme binding and enzyme activity is conserved in different proteins from all kingdoms of life. Dfp proteins of eubacteria and archaebacteria and salt tolerance proteins of yeasts and plants belong to this new family of flavoproteins. The enzymatic function of all these proteins was not known, but our experiments suggested that they catalyze a similar reaction like EpiD and/or may have similar substrates and are homododecameric flavoproteins. We demonstrate that the Nterminal domain of the Escherichia coli Dfp protein catalyzes the decarboxylation of (R)-4-phospho-Npantothenoylcysteine to 4-phosphopantetheine. This reaction is essential for coenzyme A biosynthesis.Lantibiotics such as nisin, epidermin, mersacidin, and cytolysin are a group of ribosomally synthesized and post-translationally modified antibiotic peptides (1) that are produced by and act on Gram-positive bacteria. Recently, it has been shown that the antimicrobial activity of nisin arises due to its binding to the membrane-anchored cell wall precursor lipid II and subsequent permeabilization of the plasma membrane (2).The main focus of current research is the characterization of the novel posttranslational modification reactions involved in lantibiotic biosynthesis, such as dehydration of serine and threonine residues, thioether formation, and the formation of Dalanine residues from L-serine residues (reviewed in Ref. EpiD catalyzes the oxidative decarboxylation of the C-terminal cysteine residue of epidermin precursor peptide EpiA to a (Z)-enethiol structure (5-7). Two reducing equivalents from the C-terminal cysteine residue of EpiA are removed; a double bond is formed; the coenzyme FMN is reduced to FMNH 2 , and then the C-terminal carboxyl group is removed. The unusual enethiol structure has been confirmed by two-dimensional NMR spectroscopy (8). The pK a of the enethiol group is 6.0 (9), indicating that the enethiol group is far more reactive than the thiol group of cysteine residues at physiological pH values. The formation of the S-[(Z)-2-aminovinyl]-D-cysteine structure can then be explained by the addition of the thiol group of the C-terminal enethiol to didehydroalanine at position 19 formed by the dehydration of a serine residue. EpiD has a wide substrate specificity, and most of the peptides with the sequence

General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Abstract: A molecular square with dimensions of about 4 nm, incorporating sixteen pyrene chromophores attached to four ditopic bay-functionalized perylene bisimide chromophores, has been synthesized by coordination to four Pt(II) phosphine corner units and fully characterized via NMR spectroscopy and ESI-FTICR mass spectrometry. Steady-state and time-resolved emission as well as femtosecond transient absorption studies reveal the presence of a highly efficient (>90%) and fast photoinduced energy transfer (k en ≈ 5.0 × 10 9 s -1 ) from the pyrene to the perylene bisimide chromophores and a very fast and efficient electron transfer (>94%, ket ≈ 5 × 10 11 up to 43 × 10 11 s -1 ). Spectrotemporal parametrization indicates upper excited-state electron-transfer processes, various energy and electron-transfer pathways, and chromophoric heterogeneity. Temperature-dependent time-resolved emission spectroscopy has shown that the acceptor emission lifetime increases with decreasing temperature from which an electron-transfer barrier is obtained. The extremely fast electron-transfer processes (substantially faster and more efficient than in the free ligand) that are normally only observed in solid materials, together with the closely packed structure of 20 chromophoric units, indicate that we can consider the molecular square as a monodisperse nanoaggregate: a molecularly defined ensemble of chromophores that partly behaves like a solid material.

In the course of ongoing research efforts aimed at exploring the biosynthetical potential of freshly isolated actinomycetes, the secondary metabolite profile of streptomycete strain Tu 6075 was subjected to a closer scrutiny. HPLC-diode-array analysis (HPLC-DAD) coupled with HPLC-electrospray-mass-spectrometry (HPLC-ESI-MS) revealed a pattern of metabolites in the extracts from the culture filtrate and mycelium that could not be identified by means of our HPLC-UV-Vis-Database2). The database contains about 700 reference compounds, most of which are antibiotics. Two series of homologous metabolites with retention times between 9.0 and 11.4 minutes were produced by strain Tu 6075, having end-absorption in the UV range and a side-maximum at 290 and 295nm, respectively. The spectra showed a high conformity with reference compounds of the peptide sub-library stored in Materials and Methods MicroorganismsStrain Tu 6075 was isolated from a soil sample collected in the tropical rain forest at Cape Coast, Ghana, using yeast extract-malt extract agar with addition of cycloheximide (50mg/liter) and nalidixic acid (20mg/liter)4). The strain is deposited in the culture collection of our laboratory under

Aliskiren (2(S),4(S),5(S),7(S)-

The lantibiotic mersacidin inhibits peptidoglycan biosynthesis by binding to the peptidoglycan precursor lipid II. Mersacidin contains an unsaturated thioether bridge, which is proposed to be synthesized by posttranslational modifications of threonine residue ؉15 and the COOH-terminal cysteine residue of the mersacidin precursor peptide MrsA. We show that the flavoprotein MrsD catalyzes the oxidative decarboxylation of the COOH-terminal cysteine residue of MrsA to an aminoenethiol residue. MrsD belongs to the recently described family of homo-oligomeric flavin-containing Cys decarboxylases (i.e., the HFCD protein family). Members of this protein family include the bacterial Dfp proteins (which are involved in coenzyme A biosynthesis), eukaryotic salt tolerance proteins, and further oxidative decarboxylases such as EpiD. In contrast to EpiD and Dfp, MrsD is a FAD and not an FMN-dependent flavoprotein. HFCD enzymes are characterized by a conserved His residue which is part of the active site. Exchange of this His residue for Asn led to inactivation of MrsD. The lantibiotic-synthesizing enzymes EpiD and MrsD have different substrate specificities.Lantibiotics (for "lanthionine-containing antibiotics") are a group of ribosomally synthesized and posttranslationally modified antibiotic peptides containing the thioether amino acid lanthionine as a characteristic building block (33). In the last few years, several lantibiotics with unsaturated thioether bridges at the COOH terminus have been characterized. (2), gallidermin (12), cypemycin (27), and some of the mutacins (28-30, 34), whereas mersacidin contains a COOH-terminal S-[(Z)-2-aminovinyl]-D-cysteine is present in epidermin S-[(Z)-2-aminovinyl]-3-methyl-D-cysteine residue (15, 32).Among these lantibiotics, mersacidin, which is produced by a Bacillus strain (9), is of particular interest because it is active against methicillin-resistant Staphylococcus aureus strains (8). Brötz et al. (6,7) were able to show that mersacidin inhibits the transglycosylation reaction in peptidoglycan biosynthesis by binding to the cell wall precursor lipid II [undecaprenyldiphosphoryl-N-acetylmuramic acid-(pentapeptide)-N-acetylglucosamine]. The complex formed by mersacidin and lipid II differed from the well-known vancomycin-lipid II complex, making mersacidin to a new lead structure for the development of antimicrobial compounds. The biosynthesis of the S-[(Z)-2-aminovinyl]-D-cysteineresidue of epidermin depends on the flavoenzyme EpiD. EpiD catalyzes the oxidative decarboxylation of the COOH-terminal cysteine residue of the epidermin precursor peptide EpiA to a (Z)-enethiol structure (see Fig. 7) (13,17,20,21). The unsaturated thioether bridge is formed by addition of the enethiol group to a didehydroalanine residue, produced by dehydration of Ser at position ϩ19 of EpiA (residues within the COOHterminal propeptides of lantibiotic precursor peptides are labeled with "ϩ"). Recently, molecular characterization of EpiD helped to identify homologous enzymes catalyzing the decarboxylati...