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The current study attempted to evaluate the antagonistic activity of compounds isolated and purified from the marine algae Padina arborescens during cultivation. The compounds were collected on a filter, concentrated on ODS columns and separated by HPLC. Two peaks that showed competitive progesterone binding activity with membrane progesterone receptor α (mPRα) were purified. Their physiological activity was further uncovered by in vitro and in vivo oocyte maturation and ovulation-inducing assays using zebrafish. The compounds inhibited the induction of oocyte maturation and ovulation. Moreover, the results showed that the compounds have antagonistic activity against mPRα. The purified compounds with antagonistic activity against mPRα would be considered as new pharmaceutical candidate.

Aims The aim of this study was to utilize a cryptic biosynthetic gene cluster (BGC) of a marine proteobacterium Thalassomonas actiniarum for production of new lanthipeptides by heterologous expression system. Methods and Results Based on genome mining, a new BGC of class I lanthipeptide was found in the genome sequence of a marine proteobacterium T. actiniarum. Molecular cloning was performed to construct an expression vector derived from commercially available plasmid pET-41a(+). Heterologous production of new lanthipeptides named thalassomonasins A and B was performed using the host Escherichia coli BL21(DE3) harbouring the expression vector. The structure of thalassomonasin A was determined by the interpretation of NMR and MS data. As a result, thalassomonasin A was determined to be a lanthipeptide with three units of lanthionine. The bridging pattern of the lanthionine rings in thalassomonasin A was determined by interpretation of NOESY data. The structure of thalassomonasin B was proposed by MS/MS experiment. Conclusions We succeeded in heterologous production of new class I lanthipeptides using a BGC of a marine proteobacterium T. actiniarum. Significance and Impact of the Study To the best of our knowledge, this is the first report of heterologous production of lanthipeptides derived from proteobacterial origin. There are many cryptic biosynthetic gene clusters (BCGs) of this class of lanthipeptides in proteobacterial genomes. This study may lead to the production of new lanthipeptides by utilizing the BCGs.

A polyphasic approach was used to determine the taxonomic position of a marine actinomycete, designated isolate CWH03

Bicyclic peptides, marinostatins, are protease inhibitors derived from the marine bacterium Algicola sagamiensis. The biosynthetic gene cluster of marinostatin was previously identified, although no heterologous production was reported. In this report, the biosynthetic gene cluster of marinostatin (mstA and mstB) was cloned into the expression vector pET-41a(+). As a result of the coexpression experiment, a new analogous peptide named marinostatin E was successfully produced using Escherichia coli BL21(DE3). The structure of marinostatin E was determined by a combination of chemical treatments and tandem mass spectrometry experiments. Marinostatin E exhibited inhibitory activities against chymotrypsin and subtilisin with an IC50 of 4.0 and 39.6 μm, respectively.

Linear azole-containing peptides are a class of ribosomally synthesized and post-translationally modified peptides. We performed a chemical investigation on marine actinomycetes, and new linear azole-containing peptides named spongiicolazolicins A and B were found in the MeOH extracts of a newly isolated strain Streptomyces sp. CWH03 (NBRC 114659) and two strains of S. spongiicola (strain HNM0071T: DSM 103383T and strain 531S: NBRC 113560). The strain Streptomyces sp. CWH03 was indicated to be a new species closely related to S. spongiicola by phylogenetic analysis using the genome sequence. The new peptides named spongiicolazolicins A and B were isolated from the cell of Streptomyces sp. CWH03. The partial structure of spongiicolazolicin A was determined by 2D NMR experiments. Based on data of MS/MS experiments, the chemical structures of spongiicolazolicins A and B were proposed using the amino acid sequence deduced from the precursor-encoding gene, which was found from whole-genome sequence data of Streptomyces sp. CWH03. The biosynthetic gene cluster of spongiicolazolicins was proposed based on comparative analysis with that of a known linear azole peptide goadsporin. KEY POINTS: • Streptomyces sp. CWH03 was a new species isolated from marine sediment. • New linear azole-containing peptides named spongiicolazolicins A and B were isolated. • Biosynthetic pathway of spongiicolazolicins was proposed.

Lasso peptides produced by bacteria have a very unique cyclic structure (“lasso” structure) and are resistant to protease. To date, a number of lasso peptides have been isolated from proteobacteria and actinobacteria. Many lasso peptides exhibit various biological activities, such as antibacterial activity, and are expected to have various applications. Based on study of genome mining, large numbers of biosynthetic gene cluster of lasso peptides are revealed to distribute over genomes of proteobacteria and actinobacteria. However, the biosynthetic gene clusters are cryptic in most cases. Therefore, the combination of genome mining and heterologous production is efficient method for the production of lasso peptides. To utilize lasso peptide as fine chemical, there have been several attempts to add new function to lasso peptide by genetic engineering. Currently, a more efficient lasso peptide production system is being developed to harness cryptic biosynthetic gene clusters of lasso peptide. In this review, the overview of lasso peptide study is discussed.

The thermophilic bacterium Thermosporothrix hazakensis belongs to a class of Ktedonobacteria in the phylum Chloroflexota. Lanthipeptides are a naturally occurring peptide group that contains antibacterial compounds such as nisin. To find a new lanthipeptide that is a possible candidate for an antibacterial reagent, we performed genome-mining of T. hazakensis and heterologous expression experiments. Based on genome-mining, the presence of a total of ten putative biosynthetic gene clusters for class I and class II lanthipeptides was indicated from the genome sequence of T. hazakensis. New lanthipeptides named hazakensins A and B were produced by heterologous expression of a class I lanthipeptide biosynthetic gene cluster in the expression host Escherichia coli. Co-expression of the biosynthetic gene cluster with tRNA-Glu and glutamyl-tRNA synthetase coding genes derived from T. hazakensis increased the production yield of both lanthipeptides by about 4-6 times. The chemical structures of hazakensins A and B including the bridging pattern of lanthionine/methyllanthionine rings were determined by NMR and MS experiments. Since production of hazakensins A and B was not observed in the native strain T. hazakensis, heterologous production was an effective method to obtain the lanthipeptides derived from the biosynthetic gene cluster. This is the first report of heterologous production of class I lanthipeptides originating from the filamentous green non-sulfur bacteria, to the best of our knowledge. The success of heterologous production of hazakensins may lead to the discovery and development of new lanthipeptides derived from the origins of bacteria in the phylum Chloroflexota.

The abuse or overuse of antibacterial agents for therapy and animal husbandry has caused an increased population of antimicrobial-resistant bacteria in the environment. Consequently, fewer effective antimicrobials are now available.

A new antibacterial peptide named pentaminomycin C was isolated from an extract of Streptomyces cacaoi subsp. cacaoi NBRC 12748T, along with a known peptide BE-18257A. Pentaminomycin C was determined to be a cyclic pentapeptide containing an unusual amino acid, Nδ-hydroxyarginine (5-OHArg), by a combination of ESI-MS and NMR analyses. The structure of pentaminomycin C was determined to be cyclo(–l-Leu–d-Val–l-Trp–l-5–OHArg–d-Phe–). Pentaminomycin C exhibited antibacterial activities against Gram-positive bacteria including Micrococcus luteus, Bacillus subtilis, and Staphylococcus aureus. The biosynthetic gene cluster for pentaminomycin C and BE-18257A was identified from the genome sequence data of S. cacaoi subsp. cacaoi.

Coryneazolicin is a plantazolicin family peptide, belonging to linear azole-containing peptides (LAPs). Although coryneazolicin was previously synthesized by in vitro experiments, its biological activity has not been evaluated. In this report, the heterologous production of coryneazolicin was accomplished to obtain enough coryneazolicin for biological activity tests. The structure of coryneazolicin was confirmed by ESI-MS and NMR analyses. The biological activity tests indicated that coryneazolicin possessed potent antibacterial activity and cytotoxicity. Although antibacterial activity of plantazolicin was previously reported, cytotoxicity was newly found in coryneazolicin among plantazolicin type peptides. In addition, we revealed that coryneazolicin induced apoptosis on HCT116 and HOS cancer cell lines.

The ω-ester-containing peptides (OEPs) are a group of ribosomally synthesized and post-translationally modified peptides (RiPPs). The biosynthetic gene clusters of ω-ester-containing peptides commonly include ATP-grasp ligase coding genes and are distributed over the genomes of a wide variety of bacteria. A new biosynthetic gene cluster of ω-ester-containing peptides was found in the genome sequence of the marine proteobacterium Marinomonas fungiae. Heterologous production of a new tricyclic peptide named marinomonasin was accomplished using the biosynthetic gene cluster in Escherichia coli expression host strain BL21(DE3). By ESI-MS and NMR experiments, the structure of marinomonasin was determined to be a tricyclic peptide 18 amino acids in length with one ester and two isopeptide bonds in the molecule. The bridging patterns of the three intramolecular bonds were determined by the interpretation of HMBC and NOESY data. The bridging pattern of marinomonasin was unprecedented in the ω-ester-containing peptide group. The results indicated that the ATP-grasp ligase for the production of marinomonasin was a novel enzyme possessing bifunctional activity to form one ester and two isopeptide bonds. KEY POINTS: • New tricyclic peptide marinomonasin was heterologously produced in Escherichia coli. • Marinomonasin contained one ester and two isopeptide bonds in the molecule. • The bridging pattern of intramolecular bonds was novel.

Recently, ω-ester-containing peptides (OEPs) were indicated to be a class of ribosomally synthesized and post-translationally modified peptides. Based on genome mining, new biosynthetic gene cluster of OEPs was found in the genome sequence of actinobacterium Streptomyces prunicolor. The biosynthetic gene cluster contained just two genes including precursor peptide (pruA) and ATP-grasp ligase (pruB) coding genes. Heterologous co-expression of the two genes was accomplished using expression vector pET-41a(+) in Escherichia coli. As a result, new OEP named prunipeptin was produced by this system. By site-directed mutagenesis experiment, a variant peptide prunipeptin 15HW was obtained. The bridging pattern of prunipeptin 15HW was determined by combination of chemical cleavage and MS experiments. Prunipeptin 15HW possessed bicyclic structure with an ester bond and an isopeptide bond. The ATP-grasp ligase PruB was indicated to catalyze the two different intramolecular bonds.

Lasso peptides are a class of ribosomally biosynthesized and posttranslationally modified peptides with a knot structure as a common motif. Based on a genome search, a new biosynthetic gene cluster of lasso peptide was found in the genome of the proteobacterium Sphingomonas koreensis. Interestingly, the amino acid sequence of the precursor peptide gene includes two cell adhesion motif sequences (KGD and DGR). Heterologous production of the new lasso peptide was performed using the cryptic biosynthetic gene cluster of S. koreensis. As a result, a new lasso peptide named koreensin was produced by the gene expression system in the host strain Sphingomonas subterranea. The structure of koreensin was determined by NMR and ESI-MS analysis. The three-dimensional structure of koreensin was obtained based on an NOE experiment and the coupling constants. A variant peptide (koreensin-RGD), which had RGD instead of KGD, was produced by heterologous production with site-directed mutagenesis experiment. Koreensin and koreensin-RGD did not show cell adhesion inhibitory activity, although the molecules possessed cell adhesion motifs. The possible presence of a salt bridge between the motifs in koreensin was indicated, and it may prevent the cell adhesion motif from functioning.

Using genome mining, a new cytotoxic peptide named curacozole was isolated from Streptomyces curacoi. Through ESI-MS and NMR analyses, curacozole was determined to be a macrocyclic peptide containing two isoleucine, two thiazole and three oxazole moieties. Curacozole exhibited potent cytotoxic activity against HCT116 and HOS cancer cells. The proposed biosynthetic gene cluster of curacozole was identified and compared with that of the related compound YM-216391.

A shuttle vector pHSG396Sp was constructed to perform gene expression using Sphingomonas subterranea as a host. A new lasso peptide biosynthetic gene cluster, derived from Brevundimonas diminuta, was amplified by PCR and integrated to afford a expression vector pHSG396Sp-12697L. The new lasso peptide brevunsin was successfully produced by S. subterranea, harboring the expression vector, with a high production yield (10.2 mg from 1 L culture). The chemical structure of brevunsin was established by NMR and MS/MS experiments. Based on the information obtained from the NOE experiment, the three-dimensional structure of brevunsin was determined, which indicated that brevunsin possessed a typical lasso structure. This expression vector system provides a new heterologous production method for unexplored lasso peptides that are encoded by bacterial genomes.

Based on genome-mining, a new thiopeptide globimycin was discovered from the extract of Streptomyces globisporus subsp. globisporus, along with known one radamycin. The structure of globimycin was established by a combination of 2D NMR and ESI-MS experiments, and globimycin was identified to be a structural isomer of a known thiopeptide methylsulfomycin. The proposed biosynthetic gene cluster for globimycin and radamycin was found in the genome of S. globisporus subsp. globisporus.

A new antibacterial cyclic peptide, named curacomycin (1), and its analogue dechlorocuracomycin (2) were isolated from Streptomyces curacoi (NBRC 12761T) and Streptomyces noursei (NBRC 15452T), respectively, by using genome mining. The chemical structures of these two peptides were determined by using a combination of MS (ESI) and NMR spectroscopy. The structure of compound 1 was determined to be a cyclic peptide that consisted of six amino acids, including: valine (Val), leucine (Leu), isoleucine (Ile), ornithine (Orn), β-hydroxyasparagine (OHAsn), and 5-chlorotryptophan (ClTrp). The NMR data of compound 2 were very similar to that of compound 1, which indicated that the structure of compound 2 was a dechlorinated analogue of compound 1. A comparison of the antimicrobial activities of these two peptides indicated that the presence of chlorine in compound 1 was critical for its antimicrobial activity. The proposed biosynthetic gene clusters for compounds 1 and 2 were found in the genome data of S. curacoi and S. noursei, respectively. The functions of the biosynthetic genes were considered by comparison of the two gene clusters.

A new lasso peptide named subterisin was isolated from the culture broth of Sphingomonas subterranea NBRC 16086 T . The molecular formula of subterisin was established as C 78 H 121 O 22 N 21 based on accurate mass analysis. The chemical structure of subterisin was determined by 2D NMR experiments. The presence of macrolactam ring of Gly1–Glu8 was indicated by NOESY experiment and MS/MS analysis. The three-dimensional structure of subterisin in solution was established by calculation based on NMR data. The proposed biosynthetic gene cluster of subterisin was found on the genome of S. subterranea .

Lasso peptides are ribosomally synthesized and posttranslationally modified peptides with diverse biological functions. Recent genome mining has revealed that many species of actinomycetes possibly contain biosynthetic gene clusters of lasso peptides. With genome mining for lasso peptide biosynthesis, we screened several actinomycetes for lasso peptide production using high-performance liquid chromatography and electrospray ionization–mass spectrometry. Consequently, Streptomyces cattleya was identified as a producer of a new lasso peptide named cattlecin. Analysis of amino acid content on cattlecin indicated the presence of four moles each of Asp and His, three moles each of Gly and Tyr, and one mole of Ser. Tandem mass spectrometry (MS/MS) analysis of cattlecin revealed C-terminal sequence of WHHGWYGWWDD. The peptide sequence (SYHWGDYHDWHHGWYGWWDD) was the expected amino acid sequence of cattlecin based on genome mining. As a result of MS/MS analysis, the amine residue of the first Ser was proposed to form a macrolactam ring with the β-carboxyl residue of the ninth Asp. The biosynthetic gene cluster of cattlecin comprised four genes: catA, catC, catB1, and catB2, which is typical of a lasso peptide biosynthetic gene cluster in actinomycetes.

Microviridins are a class of ribosomally synthesized and post-translationally modified peptides (RiPPs) that have been isolated from a wide variety of cyanobacterial strains. There are similar gene clusters of RiPPs distributed in the genomes of bacteria belonging to the phyla Proteobacteria and Bacteroidetes. A cryptic gene cluster for the production of microviridin-type peptide was found in the genome of the marine γ-Proteobacterium Grimontia marina. Heterologous production of new microviridin-type peptide named grimoviridin was accomplished in Escherichia coli using the biosynthetic gene cluster of G. marina. The structure of grimoviridin was determined by analysis of MS and NMR data. Grimoviridin contained one isopeptide and two ester bonds, which had exactly the same bridging pattern as other microviridin-type peptides. The absolute stereochemistries of constituent amino acids were determined to be all L-forms by modified Marfey’s method. Grimoviridin showed potent inhibitory activity against trypsin with an IC50 value of 238 nM. This is the first report of heterologous production of microviridin-type peptide using a biosynthetic gene cluster from a Proteobacterium. Key points • Heterologous production afforded new microviridin-type peptide named grimoviridin. • This is the first report of microviridin-type peptide from proteobacterial origin. • Grimoviridin showed potent inhibitory activity against trypsin.

New chymotrypsin inhibitory peptides named streptopeptolins B and C were isolated from Streptomyces olivochromogenes. Structures of streptopeptolins B and C were determined to be cyclic depsipeptides possessing 3-amino-6-hydroxy-2-piperidone unit by interpretation of NMR spectra and ESI-MS. Streptopeptolins B and C showed inhibitory activities to chymotrypsin with IC50 of 8.0 and 12.0 μg/mL, respectively.

A new lasso peptide named sphaericin was isolated from the ISP2 agar medium culture of a rare actinomycete species Planomonospora sphaerica. Amino acid composition analysis on sphaericin gave totally 15 mole of amino acids (3 mole each of Gly, Ile, Pro, and 1 mole each of Arg, Glu, Leu, Phe, Ser, Tyr). In addition to the 15 mole of amino acids, NMR experiments indicated the presence of 3 mole of Trp. The structure of sphaericin was determined to be a peptide comprising 18 amino acids, with an additional peptide bond between the amino group of Gly-1 and the gamma-carboxyl group of Glu-9 forming a macrolactam ring, as demonstrated by analyses of TOF-MS/MS and NMR spectra. The solution three-dimensional structural analysis based on NOE experiments revealed that sphaericin possessed a typical lasso structure. Based on the genome data, a biosynthetic gene cluster of sphaericin was determined to consist of four genes including sphA, sphB1, sphB2, and sphC. Sphaericin showed a specific antibacterial activity against Micrococcus luteus at the dosage of 50 micro g /disk.

Based on genome mining, a new antibacterial peptide named actinokineosin was isolated from a rare actinomycete Actinokineospora spheciospongiae. The amino acid sequence of the C-terminus of actinokineosin was established by TOF-MS/MS experiments. The amino acid sequence in the macrolactam ring was determined by TOF-MS/MS analyses after cleavage with BNPS-skatole and successive trypsin treatment. As a result of an antibacterial assay using a paper disk, actinokineosin showed antibacterial activity against Micrococcus luteus at a dosage of 50 μg per disk. From the genome sequence data of A. spheciospongiae, the biosynthetic gene cluster of actinokineosin was found and was indicated to consist of 10 genes. Among the genes, the gene aknA encoded the precursor of actinokineosin and the genes including aknC, aknB1 and aknB2 were proposed as modification enzymes to give mature actinokineosin.Genome mining is a powerful tool to find new bioactive compounds from the genome database. In this report, we succeeded in isolation and structure determination of a new antibacterial peptide named actinokineosin based on genome mining.

Isolation of a new antibacterial peptide achromosin from Streptomyces achromogenes subsp. achromogenes based on genome mining

New lantibiotic cinnamycin B was isolated from the extract of Actinomadura atramentaria NBRC 14695T, based on genome mining and chemical investigation. The partial structure of cinnamycin B was established by 2D NMR experiments, which indicated that cinnamycin B had same methyl lanthionine bridging pattern with cinnamycin. The reduction with NaBH4-NiCl2 afforded the reduced cinnamycin B, and MS/MS experiment indicated the presence of hydroxy asparatic acid in the molecule. Cinnamycin B showed an antibacterial activity against Streptomyces antibioticus with dosage of 5 μg (0.5μL, 10 mg/mL solution) at spot-on-lawn testing method. The gene cluster of cinnamycin B on the genome of A. atramentaria was identified and discussed in comparison with that of cinnamycin.

Isolation and structural determination of a new antibacterial compound demethyl-L-681,217 from Streptomyces cattleya

Streptomyces spongiicola strain 531S (NBRC 113560) was isolated from marine sediment on a beach on Sesoko Island (Okinawa, Japan). We report here the draft genome sequence of S. spongiicola 531S, in which 24 potential secondary metabolite gene clusters were predicted with antiSMASH.

Based on genome mining, a new lasso peptide specialicin was isolated from the extract of Streptomyces specialis. The structure of specialicin was established by ESI-MS and NMR analyses to be a lasso peptide with the length of 21 amino acids, containing an isopeptide bond and two disulfide bonds in the molecule. The stereochemistries of the constituent amino acids except for Trp were determined to be L and the stereochemistry of Trp at C-terminus was determined to be D. Three dimensional structure of specialicin was determined based on NOE experimental data, which indicated that specialicin possessed the similar conformational structure with siamycin I. Specialicin showed the antibacterial activity against Micrococcus luteus and the moderate anti-HIV activity against HIV-1 NL4-3. The biosynthetic gene cluster of specialicin was proposed from the genome sequence data of S. specialis.

A new siderophore named albachelin was isolated from iron deficient culture of Amycolatopsis alba. The planar structure of albachelin was elucidated by the combination of ESI-MS/MS experiment and NMR spectroscopic analyses of the gallium (III) complex. The structure of albachelin was determined to be a linear peptide consisting of 6 mol of amino acids including 3 mol of serine, one mol each of N-α-acethyl-N-δ-hydroxy-N-δ-formylornithine, N-α-methyl-N-δ-hydroxyornithine, and cyclic N-hydroxyornithine. The stereochemistries of amino acids constituting albachelin were analyzed by applying modified Marfey method to the hydrolysate of albachelin. Based on bioinformatics, we deduced and discussed the possible biosynthetic gene cluster involved in albachelin biosynthesis from the genome sequence of A. alba. By prediction of substrates for adenylation domains, a non-ribosomal peptide biosynthetase gene (AMYAL_RS0130210) was proposed to be the main biosynthetic gene for albachelin biosynthesis. The related genes including transporter for siderophore were found near the NRPS gene as a gene cluster.

Recently, we found that Streptomyces olivochromogenes NBRC 3561 produced a bioactive peptide, so we sequenced its genome to clarify its biosynthesis. We report here the draft genome sequence of S. olivochromogenes NBRC 3561, in which 40 potential secondary metabolite gene clusters were predicted by antiSMASH.

Isolation and structural determination of a new hydrophobic peptide venepeptide from Streptomyces venezuelae

A new polyacetylene carboxylic acid named montiporic acid D (1) was isolated along with a known polyacetylene alcohol, (Z)-13,15-hexadecadien-2,4-diyn-1-ol (2) from scleractinian coral Montipora digitata. The structures of compounds were determined by analyses of NMR and MS spectra.

Planomonospora sphaerica is a rare actinomycete that is a potential antibiotic producer. Here, we report the draft genome sequence of P. sphaerica strain JCM9374. This is the first genome report of a bacterium belonging to the genus Planomonospora . The genome information of P. sphaerica will contribute to studies on the structure and function of antibiotics.

Isolation and structural determination of a new macrolide, makinolide, from the newly isolated Streptomyces sp. MK-30

A new siderophore named tsukubachelin was isolated from an iron-deficient culture medium of newly isolated strain Streptomyces sp. TM-34. The chemical structure of tsukubachelin was established by the interpretation of 2D NMR and TOF-Mass spectroscopic data. The structure of tsukubachelin consists of six amino acid residues, including three serine, and one each of N-α-methyl-N-δ-hydroxy-N-δ-formylornithine, N-α-methyl-N-δ-hydroxyornithine, and cyclic N-hydroxyornithine. Because the structurally related siderophore, desferri-foroximithine, was reported to have potent angiotensin-converting enzyme inhibition activity, the inhibitory activity of desferri-tsukubachelin and desferri-foroximithine were tested for structure–activity comparison. Desferri-tsukubachelin showed 14 times more potent inhibitory activity than desferri-foroximithine. This result indicates that desferri-tsukubachelin may become a promising agent for angiotensin-converting enzyme inhibition.

Fundamental research on the mechanisms of plasma–protein interactions is performed. The possibility of controlling the modification processes of peptides is investigated by changing gas species and treatment time. Changes of the peptide composition are analyzed by X-ray photoelectron spectroscopy using [Arg8]-Vasotocin as peptide, under different discharge conditions. The XPS results show that the modifications depend on the discharging gas (such as argon, oxygen and nitrogen). Ultraviolet radiation emitted by the plasma contributes to the alteration of disulfide (S―S) bond in [Arg8]-Vasotocin, which might be responsible for the loss of biological function.

Four steroids were isolated as osteoclast-forming suppressing compounds from the medicinal mushroom Agrocybe chaxingu. Their structures were identified by spectroscopic analysis.

Two novel compounds, 3-(hydroxymethyl)-4-methylfuran-2(5 H )-one ( 1 ) and (3 R ,4 S ,1′ R )-3-(1′-hydroxyethyl)-4-methyldihydrofuran-2(3 H )-one ( 2 ), were isolated along with two known ones ( 3 and 4 ) from an edible mushroom Mycoleptodonoides aitchisonii . The structures of 1 – 4 were determined by the interpretation of spectroscopic data. Compounds 1 – 4 showed protective activity against endoplasmic reticulum (ER) stress-dependent cell death.

Previously, Park et al. isolated a new siderophore from Streptomyces peucetius ATCC 27952 based on information of the genome sequence and the structure of the siderophore was deduced to be a cyclic peptide based on MS/MS analysis. To clarify the structure of the siderophore, we cultured S. peucetius with iron deficient medium. Through several chromatographic procedures, the siderophore named peucechelin was isolated with the yield enough to perform NMR experiments. The planar structure of peucechelin was elucidated by the combination of ESI-MS experiment and NMR spectroscopic analyses of the gallium (III) complex. Unlike the previously deduced cyclic structure, the structure was determined to be a linear peptide which was similar to a known siderophore foroxymithine. The stereochemistries of amino acids constituting peucechelin were determined by applying modified Marfey method to the hydrolysate. Since the biosynthetic gene of peucechelin was formerly determined by Park et al. the similar genes were searched using genome data of other streptomycetes. As a result, the similar genes were found in the genome data of S. venezuelae and S. purpureus. Isolation and identification of siderophore was performed from the iron deficient culture of S. venezuelae. The siderophore of S. venezuelae was identified to be known compound foroxymithine by analysis ESI-MS and NMR spectra in the similar manner with peucechelin. Production of foroxymithine was also observed in the iron deficient culture of S. purpureus. Based on the genome data, comparison of the biosynthetic genes of structurally related siderophores peucechelin and foroxymithine was accomplished in discussion.

The developmentally complex soil microbe Streptomyces tendae secretes a hydrophobic peptide that restored to developmental mutants of S. coelicolor the ability to raise aerial hyphae. The S. tendae peptide, SapT, has a lantibiotic structure and molecular modelling predicts that it is amphiphilic, making it structurally and functionally similar to the SapB peptide produced by S. coelicolor. However, SapT, which bears three β-methyl lanthionine bridges and one lanthionine bridge and demonstrated limited antibiotic activity, is distinct from SapB. The amphiphilic nature of both SapT and SapB is required for their ability to serve as biosurfactants facilitating the emergence of newly formed aerial hyphae. Remarkably, SapB and SapT, and the fungal hydrophobin SC3 were shown to restore to a SapB-deficient S. coelicolor mutant the capacity to undergo complete morphogenesis, such that the extracellular addition of protein resulted in sporulation. This suggests that the initiation of aerial growth may also indirectly trigger the signal transduction events needed for differentiation. These data imply that the production of morphogenetic peptides may be common among the streptomycetes, but that while their ability to function as biosurfactants is conserved, their specific lantibiotic structure is not. Finally, the identification of a second lanthionine-containing morphogenetic peptide suggests that lantibiotic structure and function may be more diverse than previously thought.

SapB is a morphogenetic peptide that is important for aerial mycelium formation by the filamentous bacterium Streptomyces coelicolor . Production of SapB commences during aerial mycelium formation and depends on most of the genes known to be required for the morphogenesis of aerial hyphae. Furthermore, the application of purified SapB to mutants blocked in morphogenesis restores their capacity to form aerial hyphae. Here, we present evidence that SapB is a lantibiotic-like peptide that is derived by posttranslational modification from the product of a gene ( ramS ) in the four-gene ram operon, which is under the control of the regulatory gene ramR . We show that the product of another gene in the operon ( ramC ) contains a region that is similar to enzymes involved in the biosynthesis of lantibiotics, suggesting that it might be involved in the posttranslational processing of RamS. We conclude that SapB is derived from RamS through proteolytic cleavage and the introduction of four dehydroalanine residues and two lanthionine bridges. We provide an example of a morphogenetic role for an antibiotic-like molecule.

Twelve strains of algicidal bacteria were isolated from the surfacewater of the pond Shinobazu and the moat Ote-bori (Tokyo, Japan). Nine of thesestrains were considered to be in the Pseudomonas group byanalyses of 16S rDNA sequences. The methanol extract ofPseudomonas sp. K44-1 showed marked antialgal activity bythe paper disk method. Harmane (1-methyl-β-carboline) was isolated fromtheethyl acetate extract of the whole culture broth ofPseudomonas sp. K44-1 by using silica gel columnchromatography and high performance liquid chromatography (HPLC). Harmaneshowedantagonistic activities against several cyanobacterial strains at aconcentration of 30 μg disk−1.

Recently, we found that Streptomyces olivochromogenes NBRC 3561 produced a bioactive peptide, so we sequenced its genome to clarify its biosynthesis. We report here the draft genome sequence of S. olivochromogenes NBRC 3561, in which 40 potential secondary metabolite gene clusters were predicted by antiSMASH.

Four compounds were isolated from scrap cultivation beds of the mushroom, Hericium erinaceum. Compounds 1–4 were identified as methyl 4-hydroxy-3-(3-methylbutanoyl) benzoate, 2-chloro-1,3-dimethoxy-5-methylbenzene, methyl 4-chloro-3,5-dimethoxybenzoate, and 4-chloro-3,5-dimethoxybenzaldehyde by an interpretation of the NMR and MS data, respectively. This is the first reported isolation of 1 from a natural source. All the compounds showed protective activity against endoplasmic reticulum stress-dependent cell death.