Salinosporamide A, a Marine-Derived Proteasome Inhibitor, Inhibits T Cell Activation through Regulating Proliferation and the Cell Cycle

The appropriate regulation of T cell activity under inflammatory conditions is crucial for maintaining immune homeostasis. Salinosporamide A discovered as a self-resistance product from the marine bacterium Salinospora tropica, has been used as a potent proteasome inhibitor (PI). Although PIs have been developed as novel therapeutics for autoimmune diseases, due to their immunosuppressive effect, whether salinosporamide A inhibits T cell activation remains unknown. The current study finds that salinosporamide A is not cytotoxic, but controls T cell proliferation. Results from our cell cycle arrest analysis revealed that salinosporamide A leads to cell cycle arrest and regulates the expression of cyclin-dependent kinases. Under activated conditions, salinosporamide A abrogated T cell activation by T cell receptor-mediated stimulation, in which the production of cytokines was inhibited by pretreatment with salinosporamide A. Furthermore, we demonstrated that the regulation of T cell activation by salinosporamide A is mediated by suppressing the MAPK pathway. Therefore, our results suggest that salinosporamide A effectively suppresses T cell activation through regulating T cell proliferation and the cell cycle and provides great insight into the development of novel therapeutics for autoimmune diseases or graft-versus-host disease.

Extending the Salinilactone Family

Five new members of the salinilactone family, salinilactones D-H, are reported. These bicyclic lactones are produced by Salinispora bacteria and display extended or shortened alkyl side chains relative to the recently reported salinilactones A-C. They were identified by GC/MS, gas chromatographic retention index, and comparison with synthetic samples. We further investigated the occurrence of salinilactones across six newly proposed Salinispora species to gain insight into how compound production varies among taxa. The growth-inhibiting effect of this compound family on multiple biological systems including non-Salinispora actinomycetes was analyzed. Additionally, we found strong evidence for significant cytotoxicity of the title compounds.

Proximicins F and G and Diproximicin A: Aminofurans from the Marine-Derived Verrucosispora sp. SCSIO 40062 by Overexpression of PPtase Genes

Overexpression of phosphopantetheinyl transferase (PPtase)-encoding genes sfp and svp in the marine-derived Verrucosispora sp. SCSIO 40062 led to the production of two new aminofuran monomers, proximicin F (1) and proximicin G (3) and a new dimer diproximicin A (2), along with two known compounds, proximicins B (4) and C (5). Their structures were unambiguously elucidated on the basis of detailed NMR spectroscopic analysis and high-resolution electrospray ionization mass spectrometry (HRESIMS) data. Proximicin B (4) showed moderate antibacterial activities against Staphylococcus aureus, methicillin-resistant S. aureus, and Bacillus subtilis.

Cytotoxic Kendomycins Containing the Carbacylic Ansa Scaffold from the Marine-Derived Verrucosispora sp. SCSIO 07399

Three new kendomycin analogues, kendomycins B-D (1-3), were discovered from the marine-derived actinomycete Verrucosispora sp. SCSIO 07399. The structures of 1-3 were elucidated using diverse spectroscopic data analyses, X-ray crystallography, and semisynthetic derivatization. In vitro antimicrobial assays revealed that 1-3 all display good antibacterial activities against six Gram-positive bacteria with MIC values ranging from 0.5 to 8.0 μg/mL. Additionally, 1-3 were found to be moderately cytotoxic against MGC803, A549, HeLa, HepG2, MCF-7, and RKO human tumor cell lines; IC₅₀ values ranged from 2.2 to 44 μM.

Antibacterial Salinaphthoquinones from a Strain of the Bacterium Salinispora arenicola Recovered from the Marine Sediments of St. Peter and St. Paul Archipelago, Brazil

Salinaphthoquinones A-E (1-5) were isolated from a marine Salininispora arenicola strain, recovered from sediments of the St. Peter and St. Paul Archipelago, Brazil. The structures of the compounds were elucidated using a combination of spectroscopic (NMR, IR, HRESIMS) data, including single-crystal X-ray diffraction analysis. A plausible biosynthetic pathway for 1-5 is proposed. Compounds 1 to 4 displayed moderate activity against Staphylococcus aureus and Enterococcus faecalis with MIC values of 125 to 16 μg/mL.

Tiacumicin Congeners with Improved Antibacterial Activity from a Halogenase-Inactivated Mutant

Tiacumicin B (1, also known as fidaxomicin or difimicin) is a marketed drug for the treatment of Clostridium difficile infections. The biosynthetic pathway of 1 has been studied in Dactylosporangium aurantiacum subsp. hamdenensis NRRL 18085 and has enabled the identification of TiaM as a tailoring dihalogenase. Herein we report the isolation, structure elucidation, and bioactivity evaluation of 14 tiacumicin congeners (including 11 new ones) from the tiaM-inactivated mutant. A new tiacumicin congener, 3, with a propyl group at C-7‴ of the aromatic ring was found to exhibit improved antibacterial activity.

Structural and dynamic characterization of a freestanding acyl carrier protein involved in the biosynthesis of cyclic lipopeptide antibiotics

Friulimicin is a cyclic lipodecapeptide antibiotic that is produced by Actinoplanes friuliensis. Similar to the related lipopeptide drug daptomycin, the peptide skeleton of friulimicin is synthesized by a large multienzyme nonribosomal peptide synthetase (NRPS) system. The LipD protein plays a major role in the acylation reaction of friulimicin. The attachment of the fatty acid group promotes its antibiotic activity. Phylogenetic analysis reveals that LipD is most closely related to other freestanding acyl carrier proteins (ACPs), for which the genes are located near to NRPS gene clusters. Here, we report that the solution NMR structure of apo-LipD is very similar to other four-helix bundle forming ACPs from fatty acid synthase (FAS), polyketide synthase, and NRPS systems. By recording NMR dynamics data, we found that the backbone motions in holo-LipD are more restricted than in apo-LipD due to the attachment of phosphopantetheine moiety. This enhanced stability of holo-LipD was also observed in differential scanning calorimetry experiments. Furthermore, we demonstrate that, unlike several other ACPs, the folding of LipD does not depend on the presence of divalent cations, although the presence of Mg2+ or Ca2+ can increase the protein stability. We propose that small structural rearrangements in the tertiary structure of holo-LipD which lead to the enhanced stability are important for the cognate enzyme recognition for the acylation reaction. Our results also highlight the different surface charges of LipD and FAS-ACP from A. friuliensis that would allow the acyl-CoA ligase to interact preferentially with the LipD instead of binding to the FAS-ACP.

Plantactinosporasoyae sp. nov., an endophytic actinomycete isolated from soybean root [Glycine max (L.) Merr]

A novel actinomycete, designated strain NEAU-gxj3T, was isolated from soybean root [Glycine max (L.) Merr.] collected from Harbin, Heilongjiang Province, China, and characterized using a polyphasic approach. The 16S rRNA gene sequence of strain NEAU-gxj3T showed highest similarity to those of Micromonospora equina Y22T (98.2 %) and Plantactinospora endophytica YIM 68255T (98.0 %). Phylogenetic analysis based on the 16S rRNA gene and gyrB gene demonstrated that the isolate clustered with the members of the genus Plantactinospora. The chemotaxonomic properties of strain NEAU-gxj3Twere also consistent with those of members of the genus Plantactinospora. The cell wall contained meso-diaminopimelic acid and whole-cell sugars were xylose, glucose and galactose. The predominant menaquinones were MK-10(H6), MK-9(H8), MK-10(H2) and MK-10(H4). The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside. The major fatty acids were identified as anteiso-C17 : 0, iso-C16 : 0, iso-C15 : 0 and C15 : 0. A combination of DNA-DNA hybridization result and some phenotypic characteristics indicated that strain NEAU-gxj3Tcould be differentiated clearly from its closest phylogenetic relatives. Therefore, the strain is concluded to represent a novel species of the genus Plantactinospora, for which the name Plantactinospora soyae sp. nov. is proposed. The type strain is NEAU-gxj3T (=CGMCC 4.7221T=DSM 46832T).

[Identification of 3-demethylchuangxinmycin from Actinoplanes tsinanensis CPCC 200056]

Chuangxinmycin (CM) from Actinoplanes tsinanensis was an antibiotic discovered by Chinese scientists about 40 years ago. It contains a new heterocyclic system of indole fused with dihydrothiopyran, whose biosynthetic mechanism remains unclear. CM is used as an oral medicine in the treatment of bacterial infections in China. The simple structure makes CM as an attractive candidate of structure modification for improvement of antibacterial activity. Recently, we analyzed the secondary metabolites of Actinoplanes tsinanensis CPCC 200056, a CM producing strain, as a natural CM analogue. We discovered the first natural CM analogue 3-demethylchuangxinmycin (DCM) as a new natural product. Compared to CM, DCM exhibited a much weaker activity in the inhibition of the bacterial strains tested. The finding provides valuable information for the structure-activity relationship in the biosynthesis of CM.

Comparative analysis of rapamycin biosynthesis clusters between Actinoplanes sp. N902-109 and Streptomyces hygroscopicus ATCC29253

The present study was designed to identify the difference between two rapamycin biosynthetic gene clusters from Streptomyces hygroscopicus ATCC29253 and Actinoplanes sp. N902-109 by comparing the sequence and organization of the gene clusters. The biosynthetic gene cluster for rapamycin in Streptomyces hygroscopicus ATCC29253 was reported in 1995. The second rapamycin producer, Actinoplanes sp. N902-109, which was isolated in 1995, could produce more rapamycin than Streptomyces hygroscopicus ATCC29253. The genomic map of Actinoplanes sp. N902-109 has been elucidated in our laboratory. Two gene clusters were compared using the online software anti-SMASH, Glimmer 3.02 and Subsystem Technology (RAST). Comparative analysis revealed that the organization of the multifunctional polyketide synthases (PKS) genes: RapA, RapB, RapC, and NRPS-like RapP were identical in the two clusters. The genes responsible for precursor synthesis and macrolactone modification flanked the PKS core region in N902-109, while the homologs of those genes located downstream of the PKS core region in ATCC29253. Besides, no homolog of the gene encoding a putative type II thioesterase that may serve as a PKS "editing" enzyme accounted for over-production of rapamycin in N902-109, was found in ATCC29253. Furthermore, no homologs of genes rapQ (encoding a methyltransferase) and rapG in N902-109 were found in ATCC29253, however, an extra rapM gene encoding methyltransferase was discovered in ATCC29253. Two rapamycin biosynthetic gene clusters displayed overall high homology as well as some differences in gene organization and functions.

Characterization of an orphan diterpenoid biosynthetic operon from Salinispora arenicola

While more commonly associated with plants than microbes, diterpenoid natural products have been reported to have profound effects in marine microbe-microbe interactions. Intriguingly, the genome of the marine bacterium Salinispora arenicola CNS-205 contains a putative diterpenoid biosynthetic operon, terp1. Here recombinant expression studies are reported, indicating that this three-gene operon leads to the production of isopimara-8,15-dien-19-ol (4). Although 4 is not observed in pure cultures of S. arenicola, it is plausible that the terp1 operon is only expressed under certain physiologically relevant conditions such as in the presence of other marine organisms.

Insights into lomaiviticin biosynthesis. Isolation and structure elucidation of (-)-homoseongomycin

The dimeric diazofluorenes known as the lomaiviticins are produced by the marine bacterium Salinispora pacifica DPJ-0019. Investigation of the fermentation broth of DPJ-0019 has yielded the first monomeric benzo[b]fluorene isolated from this species, (-)-homoseongomycin (13). (-)-Homoseongomycin (13) is related to the known natural product seongomycin (10), which is co-produced with the monomeric diazofluorenes known as the kinamycins. We describe the synthesis of the isotopically labeled derivative homoseongomycin-d5 (14), via the intermediacy of the diazofluorene "prelomaiviticin-d5" (12). Our studies establish that (-)-homoseongomycin (13) may be derived from prelomaiviticin (11) and suggest that 13 and 10 are shunt or detoxification metabolites in lomaiviticin and kinamycin biosynthesis, respectively.

Crystallographic study of the interaction of the anti-HIV lectin actinohivin with the α(1-2)mannobiose moiety of gp120 HMTG

Actinohivin (AH) is a new potent anti-HIV lectin of microbial origin. In order to modify it to produce a more efficient drug, its three-dimensional structure has previously been determined with and without the target α(1-2)mannobiose moiety of the high-mannose-type glycan (HMTG) attached to HIV-1 gp120. However, ambiguity remained in the structures owing to packing disorder that was possibly associated with peptide fragments attached at the N-terminus. To resolve these problems, the duration of cultivation of the AH-producing strain was examined and it was found that in a sample obtained from a 20 d culture the heterogeneous fragments were completely removed to produce mature AH with high homogeneity. In addition, the purification procedures were simplified in order to increase the yield of AH and the addition of solvents was also examined in order to increase the solubility of AH. AH thus obtained was successfully crystallized with high reproducibility in a different form to the previously obtained crystals. The crystal diffracted well to beyond 1.90 Å resolution and the crystallographic data suggested that it contained no packing disorder.

Selective quantification by 2D HSQC0 spectroscopy of thiocoraline in an extract from a sponge-derived Verrucosispora sp

We recently developed a 2D 1H-13C HSQC0 approach to quantify individual chemicals in complex mixtures. The HSQC0 approach has been implemented in phase-cycled and gradient-selective versions. As in quantitative 1D NMR, the normalized integrated signal intensities in HSQC0 are proportional to the concentrations of individual chemicals in the mixture. We applied the HSQC0 approach to selectively quantify thiocoraline present at a level of 1% w/w in an extract from a Verrucosispora sp. isolated from the sponge Chondrilla caribensis f. caribensis. We expect that this approach can be used to quantify other natural products of interest in extracts without prior purification.

Isolation and identification of 5-hydroxyl-5-methyl-2-hexenoic acid from Actinoplanes sp. HBDN08 with antifungal activity

A bioactivity-guided approach was employed to isolate and determine the chemical identity of bioactive constituents with antifungal activity from Actinoplanes sp. HBDN08. The structure of the antifungal metabolite was elucidated as 5-hydroxyl-5-methyl-2-hexenoic acid on the basis of spectral analysis. This compound showed strong in vitro antifungal activity against Botrytis cinerea, Cladosporium cucumerinum and Corynespora cassiicola, with an IC(50) of 32.45, 27.17, and 30.66 mg/L, respectively; however, it only moderately inhibited hyphal growth of Rhizoctonia solani with an IC(50) of 61.64 mg/L. The in vivo antifungal activity under greenhouse conditions demonstrated that 5-hydroxyl-5-methyl-2-hexenoic acid could effectively control the diseases caused by B. cinerea, C. cucumerinum and C. cassiicola with 71.42%, 78.63% and 65.13% control values at 350 mg/L, respectively. This strong antifungal activity suggests that 5-hydroxyl-5-methyl-2-hexenoic acid might be a promising candidate for new antifungal agents.

Isolation and identification of chlorinated genistein from Actinoplanes sp. HBDN08 with antioxidant and antitumor activities

A strain Actinoplanes sp. HBDN08 was screened by PCR-guided method using primers derived from conserved regions of halogenase genes. A new chlorinated isoflavone, 3',8-dichlorogenistein (1), along with 8-chlorogenistein (2) were isolated from the fermentation broth of Actinoplanes sp. HBDN08. Their structures were elucidated on the basis of extensive 1D and 2D NMR as well as HRESI-MS, ESI-MS, UV, and IR spectroscopic analyses. The origin of the two compounds was also investigated by high-performance liquid chromatography (HPLC) analysis. The results demonstrated that they were not biosynthesized but derived from the biotransformation of genistein by Actinoplanes sp. HBDN08. The antioxidant activities of the isolated compounds 1 and 2 were evaluated by using the lipid peroxidation assay. Their antitumor activities were calculated according to the inhibitory rate of cell proliferation against the human breast cancer cell line MDA-MB-231. The results indicated that compounds 1 (IC(50) = 5.2 microM) and 2 (IC(50) = 7.5 microM) showed stronger antioxidant activities than genistein (IC(50) = 13.6 microM). In comparison with the antitumor activities of genistein, those of compounds 1 and 2 increased 7.7- and 2.6-fold, respectively. These results suggest that the PCR-guided screening strategy is a rapid method for obtaining halometabolite-producing strains. Moreover, these results reveal that chlorination has significant effects on the bioactivities of genistein. This could be important information for studying the structure-activity relationships of genistein.

Glycerol affects the acyl moieties of teicoplanin components produced by Actinoplanes teichomyceticus MSl2210

Teicoplanin, a glycopeptide antibiotic, is composed of five main components, denoted T-A2-1 to T-A2-5. We investigated the use of glycerol as a carbon source affecting the teicoplanin components and its acyl moieties. As a result, we show the change of teicoplanin components, as well as an increase of total teicoplanin yields, caused by the addition of glycerol to the production medium. Analysis of the total cell lipids upon the addition of glycerol also showed a corresponding change in the proportion of teicoplanin, suggesting that glycerol strongly affects a change of teicoplanin branched acyl moieties.

Tryptamine derived amides with thiazole ring system from Thermoactinomyces strain TA66-2

A moderately thermophilic actinomycete strain, which was identified as Thermoactinomyces strain TA66-2, was isolated from hot-spring water. Fermentation, followed by solvent partition and chromatographic separations, resulted in the isolation of two new and two known molecules. The structures of the new compounds were elucidated as 2-(1-Propionylaminoethyl)thiazole-4-carboxylic acid [2-(1H-indol-3-yl)ethyl]amide and 2-(1-Acetylaminoethyl)thiazole-4-carboxylic acid [2-(1H-indol-3-yl)-ethyl]amide by using spectral methods (1D-, 2D-NMR and LC-ESI-MS).

Structural basis for cyclodextrin recognition by Thermoactinomyces vulgaris cyclo/maltodextrin-binding protein

The crystal structure of a Thermoactinomyces vulgaris cyclo/maltodextrin-binding protein (TvuCMBP) complexed with gamma-cyclodextrin has been determined. Like Escherichia coli maltodextrin-binding protein (EcoMBP) and other bacterial sugar-binding proteins, TvuCMBP consists of two domains, an N- and a C-domain, both of which are composed of a central beta-sheet surrounded by alpha-helices; the domains are joined by a hinge region containing three segments. gamma-Cyclodextrin is located at a cleft formed by the two domains. A common functional conformational change has been reported in this protein family, which involves switching from an open form to a sugar-transporter bindable form, designated a closed form. The TvuCMBP-gamma-cyclodextrin complex structurally resembles the closed form of EcoMBP, indicating that TvuCMBP complexed with gamma-cyclodextrin adopts the closed form. The fluorescence measurements also showed that the affinities of TvuCMBP for cyclodextrins were almost equal to those for maltooligosaccharides. Despite having similar folds, the sugar-binding site of the N-domain part of TvuCMBP and other bacterial sugar-binding proteins are strikingly different. In TvuCMBP, the side-chain of Leu59 protrudes from the N-domain part into the sugar-binding cleft and orients toward the central cavity of gamma-cyclodextrin, thus Leu59 appears to play the key role in binding. The cleft of the sugar-binding site of TvuCMBP is also wider than that of EcoMBP. These findings suggest that the sugar-binding site of the N-domain part and the wide cleft are critical in determining the specificity of TvuCMBP for gamma-cyclodextrin.

Biosynthetic convergence of salinosporamides A and B in the marine actinomycete Salinispora tropica

[structure: see text] Feeding experiments with stable isotopes established that the potent 20S-proteasome inhibitors salinosporamide A and B are biosynthesized in the marine bacterium Salinispora tropica from three biosynthetic building blocks, namely, acetate, beta-hydroxy-2'-cyclohexenylalanine, and either butyrate or a tetrose-derived chlorinated molecule. The unexpected observation that the chlorinated four-carbon residue in salinosporamide A is derived from a different metabolic origin than the non-chlorinated four-carbon unit in salinosporamide B is suggestive of a convergent biosynthesis to these two anticancer natural products.

Actinocatenispora thailandica gen. nov., sp. nov., a new member of the family Micromonosporaceae

Two actinomycete strains, TT2-10T and TT2-3, which produced long spore chains (more than 10 spores per chain), were isolated from peat swamp forest soil in Pattaloong Province, Thailand. Their taxonomic positions were determined using a polyphasic approach. The chemotaxonomic characteristics of these strains coincided with those of the family Micromonosporaceae, i.e. cell-wall chemotype II, muramic acid of the N-glycolyl type, whole-cell sugar pattern D and type II phospholipids. Analysis of the 16S rRNA gene sequences also indicated that these strains constitute a distinct lineage within the family Micromonosporaceae, sharing 91.3–93.8 % sequence similarity with members of this family. On the basis of their phenotypic and genotypic characteristics and their phylogenetic position, these strains represent a novel genus and species, for which the name Actinocatenispora thailandica gen. nov., sp. nov. is proposed. The type strain of Actinocatenispora thailandica is strain TT2-10T (=JCM 12343T=PCU 235T=DSM 44816T).

Three novel species of the genus Catellatospora, Catellatospora chokoriensis sp. nov., Catellatospora coxensis sp. nov. and Catellatospora bangladeshensis sp. nov., and transfer of Catellatospora citrea subsp. methionotrophica Asano and Kawamoto 1988 to Catellatospora methionotrophica sp. nov., comb. nov

Three Gram-positive, aerobic, non-motile, mesophilic strains, designated 2-25(1)T, 2-29(17)T and 2-70(23)T, were isolated from sandy soil from Chokoria, Cox's Bazar, Bangladesh. The organisms produce short chains of non-motile spores that emerge singly or in tufts from vegetative hyphae on the surface of agar media. A comparative phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolates formed a distinct clade within the evolutionary radiation of the family Micromonosporaceae and clustered with members of the genus Catellatospora. The nearest neighbours were Catellatospora citrea subsp. citrea and C. citrea subsp. methionotrophica. Chemotaxonomic data, such as the presence of meso- and 3-hydroxy-diaminopimelic acids, N-glycolyl type muramic acid, arabinose and xylose and glucose in whole-cell hydrolysates, phosphatidylethanolamine as a diagnostic phospholipid, a tetrahydrogenated menaquinone with 9 isoprene units as a major menaquinone and fatty acid profiles predominated by iso-branched hexadecanoic acid and iso-branched pentadecanoic acid, supported the affiliation of the novel isolates to the genus Catellatospora. The results of DNA–DNA hybridization and physiological and biochemical tests allowed the novel isolates to be differentiated genotypically and phenotypically from the three recognized Catellatospora species. The three isolates therefore represent novel species for which the names Catellatospora chokoriensis sp. nov. [type strain 2-25(1)T=JCM 12950T=DSM 44900T], Catellatospora coxensis sp. nov. [type strain 2-29(17)T=JCM 12951T=DSM 44901T] and Catellatospora bangladeshensis sp. nov. [type strain 2-70(23)T=JCM 12949T=DSM 44899T], are proposed. DNA–DNA hybridization tests with C. citrea subsp. citrea and C. citrea subsp. methionotrophica, in combination with chemotaxonomic and physiological data, demonstrated that C. citrea subsp. methionotrophica should be elevated to a separate species for which the name Catellatospora methionotrophica sp. nov., comb. nov. is proposed (type strain JCM 7543T=DSM 44098T).

Complexes of Thermoactinomyces vulgaris R-47 alpha-amylase 1 and pullulan model oligossacharides provide new insight into the mechanism for recognizing substrates with alpha-(1,6) glycosidic linkages

Thermoactinomyces vulgaris R-47 alpha-amylase 1 (TVAI) has unique hydrolyzing activities for pullulan with sequence repeats of alpha-(1,4), alpha-(1,4), and alpha-(1,6) glycosidic linkages, as well as for starch. TVAI mainly hydrolyzes alpha-(1,4) glycosidic linkages to produce a panose, but it also hydrolyzes alpha-(1,6) glycosidic linkages with a lesser efficiency. X-ray structures of three complexes comprising an inactive mutant TVAI (D356N or D356N/E396Q) and a pullulan model oligosaccharide (P2; [Glc-alpha-(1,6)-Glc-alpha-(1,4)-Glc-alpha-(1,4)]2 or P5; [Glc-alpha-(1,6)-Glc-alpha-(1,4)-Glc-alpha-(1,4)]5) were determined. The complex D356N/P2 is a mimic of the enzyme/product complex in the main catalytic reaction of TVAI, and a structural comparison with Aspergillus oryzaealpha-amylase showed that the (-) subsites of TVAI are responsible for recognizing both starch and pullulan. D356N/E396Q/P2 and D356N/E396Q/P5 provided models of the enzyme/substrate complex recognizing the alpha-(1,6) glycosidic linkage at the hydrolyzing site. They showed that only subsites -1 and -2 at the nonreducing end of TVAI are effective in the hydrolysis of alpha-(1,6) glycosidic linkages, leading to weak interactions between substrates and the enzyme. Domain N of TVAI is a starch-binding domain acting as an anchor in the catalytic reaction of the enzyme. In this study, additional substrates were also found to bind to domain N, suggesting that domain N also functions as a pullulan-binding domain.

Occurrence and characterization of actinobacteria and thermoactinomycetes isolated from pulp and board samples containing recycled fibres

The aim of this study was to characterize the actinobacterial population present in pulps and boards containing recycled fibres. A total of 107 isolates was identified on the basis of their pigmentation, morphological properties, fatty acid profiles and growth temperature. Of the wet pulp and water sample isolates (n=87), 74.7% belonged to the genus Streptomyces, 17.2% to Nocardiopsis and 8.0% to thermoactinomycetes, whereas all the board sample isolates (n=20) were thermoactinomycetes. The identification of 53 isolates was continued by molecular methods. Partial 16S rDNA sequencing and automated ribotyping divided the Streptomyces isolates (n=31) into 14 different taxa. The most common streptomycetes were the mesophilic S. albidoflavus and moderately thermophilic S. thermocarboxydus. The Nocardiopsis isolates (n=11) belonged to six different taxa, whereas the thermoactinomycetes were mainly members of the species Laceyella sacchari (formerly Thermoactinomyces sacchari). The results indicated the probable presence of one or more new species within each of these genera. Obviously, the drying stage used in the board making processes had eliminated all members of the species Streptomyces and Nocardiopsis present in the wet recycled fibre pulp samples. Only the thermotolerant endospores of L. sacchari were still present in the final products. The potential of automated ribotyping for identifying actinobacteria was indicated, as soon as comprehensive identification libraries became available.

New Cytotoxic Salinosporamides from the Marine ActinomyceteSalinisporatropica

An extensive study of the secondary metabolites produced by the obligate marine actinomycete Salinispora tropica (strain CNB-392), the producing microbe of the potent proteasome inhibitor salinosporamide A (1), has led to the isolation of seven related gamma-lactams. The most important of these compounds were salinosporamide B (3), which is the deschloro-analogue of 1, and salinosporamide C (4), which is a decarboxylated pyrrole analogue. New SAR data for all eight compounds, derived from extensive testing against the human colon carcinoma HCT-116 and the 60-cell-line panel at the NCI, indicate that the chloroethyl moiety plays a major role in the enhanced activity of 1.

Mechercharmycins A and B, cytotoxic substances from marine-derived Thermoactinomyces sp. YM3-251

A new cytotoxic substance named mechercharmycin A was isolated from marine-derived Thermoactinomyces sp. YM3-251. The structure of mechercharmycin A was determined by an X-ray crystallographic analysis to be cyclic peptide-like and bearing four oxazoles and a thiazole. Mechercharmycin B, a linear congener of mechercharmycin A, was also isolated from the same bacterium. Mechercharmycin A exhibited relatively strong antitumor activity, whereas mechercharmycin B exhibited almost no such activity.

Asanoa iriomotensis sp. nov., isolated from mangrove soil

During a study of the distribution of actinomycetes in a mangrove zone, a strain forming spore chains borne on the tip of short sporophores arising directly from the agar surface was isolated from soil. The isolate contained glutamic acid, glycine, alanine and meso-diaminopimelic acid as cell-wall amino acids, menaquinone MK-10(H(6), H(8)), fatty acid type 2d and xylose in the whole-cell hydrolysate. The 16S rRNA gene sequence of the isolate formed a monophyletic cluster with the members of the genus Asanoa in the family Micromonosporaceae. On the basis of morphological and chemotaxonomic characteristics, phylogenetic analysis and DNA-DNA hybridization, a novel species of the genus Asanoa is proposed for strain TT 97-02(T) (=NBRC 100142(T)=DSM 44745(T)), Asanoa iriomotensis sp. nov.

Proposal of the genus Thermoactinomyces sensu stricto and three new genera, Laceyella, Thermoflavimicrobium and Seinonella, on the basis of phenotypic, phylogenetic and chemotaxonomic analyses

Phylogenetic analysis based on 16S rRNA gene sequences revealed that Thermoactinomyces species with validly published names can be assigned to four clusters or lineages. The type strains of Thermoactinomyces sacchari and Thermoactinomyces putidus were differentiated from the type strains of Thermoactinomyces vulgaris and Thermoactinomyces intermedius by the predominant menaquinone and fatty acid profiles. The type strains of Thermoactinomyces dichotomicus and Thermoactinomyces peptonophilus formed lines of descent distinct from other Thermoactinomyces species. Thermoactinomyces dichotomicus KCTC 3667T was distinguishable from the type strains of Thermoactinomyces vulgaris and Thermoactinomyces intermedius by the contents of two fatty acids, iso-C16 : 0 and iso-C17 : 0. Thermoactinomyces dichotomicus could be distinguished from other Thermoactinomyces species by DNA G+C content and some phenotypic properties, particularly its property of forming a yellow colour. The type strain of Thermoactinomyces peptonophilus was distinguishable from other Thermoactinomyces species by differences in menaquinone profile, major fatty acids, DNA G+C content and some physiological properties including optimal growth temperature. On the basis of these data, the creation of three new genera, Laceyella, Thermoflavimicrobium and Seinonella, is proposed in addition to the genus Thermoactinomyces sensu stricto. The genus Laceyella gen. nov. is proposed to accommodate Thermoactinomyces sacchari and Thermoactinomyces putidus as Laceyella sacchari comb. nov. and Laceyella putida comb. nov., the genus Thermoflavimicrobium gen. nov. is proposed for Thermoactinomyces dichotomicus as Thermoflavimicrobium dichotomicum comb. nov. and the genus Seinonella gen. nov. is proposed for Thermoactinomyces peptonophilus as Seinonella peptonophila comb. nov.

Proposal to transfer Catellatospora ferruginea and 'Catellatospora ishikariense' to Asanoa gen. nov. as Asanoa ferruginea comb. nov. and Asanoa ishikariensis sp. nov., with emended description of the genus Catellatospora

The taxonomic position of Catellatospora ferruginea and 'Catellatospora ishikariense' was investigated by phylogenetic, chemotaxonomic and physiological characterization. The 16S rDNA sequences of the organisms were compared with those of members of the genus Catellatospora and other genera of the Micromonosporaceae and phylogenetic trees were inferred by using distance-matrix and parsimony methods. The organisms formed a distinct cluster within the radiation of this family that was supported by a high bootstrap value, of 100%. The nearest neighbours were members of the genera Catenuloplanes and Verrucosispora. The organisms were readily differentiated from all of the validly described genera of the family Micromonosporaceae by using a battery of chemical and morphological characters, and the name Asanoa gen. nov. is proposed. On the basis of phenotypic and DNA-DNA hybridization data, Asanoa ferruginea comb. nov. (type strain IMSNU 22009T = IFO 14496T DSM 44099T) and Asanoa ishikariensis sp. nov. (type strain IMSNU 22004T = IFO 14551T) are described.

Structure, stereochemistry, and biological activity of integramycin, a novel hexacyclic natural product produced by Actinoplanes sp. that inhibits HIV-1 integrase

[structure: see text] HIV-1 integrase is a critical enzyme for viral replication, and its inhibition is an emerging target for potential antiviral chemotherapy. We have discovered a novel inhibitor, integramycin, from screening of fermentation extracts using an in vitro assay. Integramycin possesses a hexacyclic ring system and exhibited an IC50 value of 4 microM against HIV-1 integrase (strand transfer). The isolation, structure elucidation, stereochemistry, conformation, and biological activity has been described.

NMR-based identification of cell wall anionic polymers of Spirilliplanes yamanashiensis VKM Ac-1993(T)

The cell wall of Spirilliplanes yamanashiensis VKM Ac-1993(T) contains four anionic polymers, viz., three teichoic acids and a sugar-1-phosphate polymer. The following are the structures of the teichoic acids: poly[-6-beta-D-glucopyranosyl-(1-->2)-glycerol phosphate] (PI), 1,3-poly(glycerol phosphate) bearing N-acetyl-alpha-D-glucosamine residues at O-2 (70%) (PII), and poly[-6-N-acetyl-alpha-D-glucosaminyl-(1-->2)-glycerol phosphate] (PIII). The repeating unit of the fourth polymer (PIV) has the structure of -6-alpha-D-GlcpNAc-(1-->6)-alpha-D-GlcpNAc-1-P- with a 3-O-methyl-alpha-D-mannopyranosyl residues at position 3 of some 6-phosphorylated N-acetylglucosamine residues (50%). Polymers PI, PIII and PIV have not hitherto been found in prokaryotic cell walls.

Phylogenetic analysis of the genus Actinoplanes and transfer of Actinoplanes minutisporangius Ruan et al. 1986 and 'Actinoplanes aurantiacus' to Cryptosporangium minutisporangium comb. nov. and Cryptosporangium aurantiacum sp. nov

The phylogenetic structure of the genus Actinoplanes was determined by comparative 16S rDNA sequence analysis of the type strains of all validly described Actinoplanes species and other strains of Actinoplanes. Actinoplanes minutisporangius IFO 15962T and 'Actinoplanes aurantiacus' IFO 13967 were placed outside the family Micromonosporaceae and appeared to be closely related to the genus Cryptosporangium. On the basis of their morphological and chemotaxonomic characteristics and phylogenetic analysis, these strains were reclassified into the genus Cryptosporangium. DNA-DNA hybridization revealed that these strains differed from the species previously described in this genus. Therefore, the transfer is proposed of Actinoplanes minutisporangius Ruan et al. 1986 and 'Actinoplanes aurantiacus' IFO 13967 to the genus Cryptosporangium as Cryptosporangium minutisporangium comb. nov. and Cryptosporangium aurantiacum sp. nov.

A new genus of the order Actinomycetales, Virgosporangium gen. nov., with descriptions of Virgosporangium ochraceum sp. nov. and Virgosporangium aurantiacum sp. nov

Four motile spored strains were isolated from soil samples collected in Japan. The cultures formed long, narrow sporangia on short sporangiophores directly on the substrate mycelium. The sporangia develop singly or in clusters above the surface of the substrate. Each sporangium contains a single row of six or more motile spores. Glutamic acid, glucosamine, glycine, alanine and 3-OH-diaminopimelic acid are present in the cell wall; the whole-cell sugars are 3-O-methylmannose, rhamnose, mannose, arabinose, galactose, xylose and glucose; and the predominant menaquinones are 10(H4), 10(H6) and 10(H8). The diagnostic phospholipid is phosphatidylethanolamine. The acyl type of the muramic acid is glycolyl. The G+C content is 71 mol%. Mycolic acids are absent. The chemotaxonomic data indicate that these strains belong to the family Micromonosporaceae. Analysis of 165 rDNA sequences suggested that these organisms fall into a distinct clade within the family Micromonosporaceae for which a new genus, Virgosporangium gen. nov., is proposed containing the species Virgosporangium ochraceum sp. nov. (strains YU655-43T, YU793-41 and YU794-41) and Virgosporangium aurantiacum sp. nov. (strain YU438-5T).

Polyether antibiotic CP44,161

The crystal structure of antibiotic CP44,161, 6-(7-(2-ethyl-2-[5-(1-hydroxymethyl)-5-methyl-2,3,4,5-tetrahydro-2-furyl]-4,10,-12-trimethyl-1,6,8-trioxadispiro[4.1.5.3]pentadec-13-en-9-yl)-4-hydroxy-3,5-dimethyl-6-oxononyl)-2-hydroxy-3-methylbenzoic acid monohydrate, C43H66O10.H2O, has been determined by X-ray crystallography. The molecule adopts a cyclic conformation, with a centrally located water molecule contributing to the stability of the conformation through hydrogen-bonding interactions.

Catenuloplanes crispus (Petrolini et al. 1993) comb. nov.: incorporation of the genus Planopolyspora Petrolini 1993 into the genus Catenuloplanes Yokota et al. 1993 with an amended description of the genus Catenuloplanes

The taxonomic position of the genus Planopolyspora comprising a single species, Planopolyspora crispa, was reviewed. This genus was originally characterized by formation of long, curly and sometimes branching sporangia containing numerous zoospores arranged in a single row and by the presence of meso-diaminopimelic acid and madurose (3-O-methyl-D-galactose) in whole-cell hydrolysates. However, our chemotaxonomic analyses of the type strain of P. crispa did not agree with the original description. The peptidoglycan contained L-lysine but not meso-diaminopimelic acid, and the whole-cell hydrolysate contained xylose as the characteristic sugar but not madurose. These characteristics and other chemotaxonomic profiles (e.g. menaquinone, phospholipid and cellular fatty acid compositions) of the genus Planopolyspora coincided with those of the genus Catenuloplanes. These two genera also had very similar morphological characteristics, but in the original description of the genus Catenuloplanes the presence of sporangia was not referred to. This difference is considered to originate from a divergence of views owing to the ambiguity of the definition of the term 'sporangium' in actinomycete morphology. Phylogenetic analysis based on 16S rDNA sequences also supported the proposal that the genera Planopolyspora and Catenuloplanes should be combined into one genus. Levels of DNA relatedness among the type strains of P. crispa and six Catenuloplanes species and their cultural, physiological and biochemical characteristics indicated that P. crispa should be classified as an independent species of the genus Catenuloplanes, which has priority over the genus Planopolyspora. Therefore, it is proposed that Planopolyspora crispa be transferred to the genus Catenuloplanes as Catenuloplanes crispus comb. nov.

Novel rhodococci and other mycolate actinomycetes from the deep sea

A large number of mycolate actinomycetes have been recovered from deep-sea sediments in the NW Pacific Ocean using selective isolation methods. The isolates were putatively assigned to the genus Rhodococcus on the basis of colony characteristics and mycolic acid profiles. The diversity among these isolates and their relationship to type strains of Rhodococcus and other mycolate taxa were assessed by Curie point pyrolysis mass spectrometry (PyMS). Three major (A, C, D) and two minor (B, E) groups were defined by PyMS. Cluster A was a large group of isolates recovered from sediment in the Izu Bonin Trench (2679 m); Cluster C comprised isolates from both the Izu Bonin Trench (6390 and 6499 m) and from the Japan Trench (4418, 6048 and 6455 m). These Cluster C isolates showed close similarity to Dietzia maris and this was subsequently confirmed using molecular methods. Cluster D contained isolates recovered from a sediment taken from a depth of 1168 m in Sagami Bay and were identified as members of the terrestrial species Rhodococcus luteus. Clusters B and E had close affinities with members of the genera Gordonia and Mycobacterium. The presence of Thermoactinomyces in certain of the deep-sea sediments studied was indicative of the movement of terrestrial material into the ocean depths. 16S ribosomal RNA gene sequence analyses produced excellent definition of most genera of the mycolata, and indicated that the among the deep sea isolates (1) were novel species of Corynebacterium, Gordonia and Mycobacterium, and (2) a Sea of Japan isolate the phylogenetic depth of which suggests the possibility of a new genus. Polyphasic taxonomic analysis revealed considerable diversity among the deep sea rhodococci and evidence for recently diverged species or DNA groups.

A taxonomic review of the genus Microbispora by analysis of ribosomal protein AT-L30

We analyzed the ribosomal AT-L30 proteins from 13 type strains of species belonging to the genera Microbispora and Actinomadura. The electrophoretic mobilities of the AT-L30 preparations from Microbispora strains, as determined by two-dimensional polyacrylamide gel electrophoresis, revealed that the members of the genus Microbispora are phylogenetically homogeneous. The results of partial amino acid sequencing of AT-L30 preparations from several representative Microbispora strains supported the separation of the genus Microbispora from other related genera. The amino acid sequences of the AT-L30 proteins from strains of species belonging to the genus Actinomadura sensu stricto displayed a diversity that exemplified the low levels of amino acid sequence homology within the genus. This diversity was considered to be a characteristic typical of the genus Actinomadura.