Cloning and identification of saprolmycin biosynthetic gene cluster from Streptomyces sp. TK08046.

Saprolmycins A-E are anti-Saprolegnia parasitica antibiotics. To identify the gene cluster for saprolmycin biosynthesis in Streptomyces sp. TK08046, polymerase chain reaction using aromatase and cyclase gene-specific primers was performed; the spr gene cluster, which codes for angucycline biosynthesis, was obtained from the strain. The cluster consists of 36 open reading frames, including minimal polyketide synthase, ketoreductase, aromatase, cyclase, oxygenase, and deoxy sugar biosynthetic genes, as defined by homology to the corresponding genes of the urdamycin, Sch-47554, and grincamycin biosynthetic gene clusters in Streptomyces fradiae, Streptomyces sp. SCC-2136, and Streptomyces lusitanus, respectively. To establish the function of the gene cluster, an expression cosmid vector containing all 36 open reading frames was introduced into Streptomyces lividans TK23. The transformant was confirmed to express the biosynthetic genes and produce saprolmycins by liquid chromatography-mass spectrometry analysis of the extract.

Borrelidin Isolated from Streptomyces sp. Inhibited Adipocyte Differentiation in 3T3-L1 Cells via Several Factors Including GATA-Binding Protein 3.

An inhibitor of 3T3-L1 adipocyte differentiation was isolated from Streptomyces sp. TK08330 and identified by spectroscopy as the 18-membered macrolide borrelidin. Treatment with 1.0 µM borrelidin suppressed intracellular lipid accumulation by 80% and inhibited the expression of adipocyte-specific genes. Borrelidin suppressed the mRNA expression of two master regulators of adipocyte differentiation, peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer binding protein (C/EBPα). Studies on well-known upstream regulators of PPARγ revealed that borrelidin down-regulated C/EBPδ mRNA expression but did not affect expression of C/EBPß. Borrelidin increased mRNA expression of negative regulators of differentiation such as GATA-binding protein (GATA) 3, Krüppel-like factor (KLF) 3 and KLF7, as well as positive regulators, KLF4, KLF6 and KLF15, at early stages of differentiation. To elucidate a primary mediator of borrelidin differentiation inhibitory activity, small interfering RNA (siRNA) transfection experiments were performed. The mRNA expression of PPARγ, which was down-regulated by borrelidin, was not changed by KLF3 and KLF7 siRNA treatment. In contrast, expression of PPARγ in GATA-3 siRNA-treated cells was not significantly different from that of control siRNA-treated cells. Borrelidin significantly inhibited lipid accumulation in control siRNA-treated cells, and treatment with GATA-3 siRNA slightly reduced the inhibitory effect of borrelidin. These results indicate that borrelidin inhibited adipocyte differentiation partially via GATA-3.

A Compound Inhibits Biofilm Formation of Staphylococcus aureus from Streptomyces.

Biofilm is one virulence factor of bacteria. It contributes not only to bacterial adherence to many kinds of infection-establishing surfaces, but also to bacterial resistance against antimicrobial agents and antiseptic agents. Thus, inhibitors of bacterial biofilm formation should be useful in the prevention of infections. We found that a culture of Streptomyces sp. strain MC11024 showed inhibitory activity on biofilm formation by Staphylococcus aureus and isolated streptorubin B as an inhibitor of this formation in S. aureus. The biofilm formation of methicillin resistant S. aureus (MRSA) N315 was reduced to less than 30% at 1 µg/mL of streptorubin B, and at this concentration cell growth was not affected. Our study suggests that streptorubin B has the potential to be a leading compound of anti-infectious agents of S. aureus.

Probable novel MEP pathway inhibitor and its binding protein, IspG.

A second isoprene unit biosynthetic pathway, via 2-C-methyl-D-erythritol 4-phosphate (MEP), was discovered in the 1990s. We screened and isolated the cyclic dipeptide, maculosin, which is a probable novel MEP pathway inhibitor, from the culture broth of Bacillus subtilis strain KN07. To identify the target enzyme of maculosin, we applied an avidin-biotin complex method using biotinylated maculosin and the lysates of seven Escherichia coli strains, each overexpressing one enzyme of the MEP pathway, and performed quartz crystal microbalance (QCM) experiments using maculosin and each enzyme. The results indicate that IspG, the sixth enzyme on the MEP pathway, was bound to maculosin.

Identification of an algal carbon fixation-enhancing factor extracted from Paramecium bursaria.

The green ciliate Paramecium bursaria contains several hundred symbiotic Chlorella species. We previously reported that symbiotic algal carbon fixation is enhanced by P. bursaria extracts and that the enhancing factor is a heat-stable, low-molecular-weight, water-soluble compound. To identify the factor, further experiments were carried out. The enhancing activity remained even when organic compounds in the extract were completely combusted at 700 degrees C, suggesting that the factor is an inorganic substance. Measurement of the major cations, K+, Ca2+, and Mg2+, by an electrode and titration of the extract resulted in concentrations of 0.90 mM, 0.55 mM, and 0.21 mM, respectively. To evaluate the effect of these cations, a mixture of the cations at the measured concentrations was prepared, and symbiotic algal carbon fixation was measured in the solution. The results demonstrated that the fixation was enhanced to the same extent as with the P. bursaria extract, and thus this mixture of K+, Ca2+, and Mg2+ was concluded to be the carbon fixation-enhancing factor. There was no effect of the cation mixture on free-living C. vulgaris. Comparison of the cation concentrations of nonsymbiotic and symbiotic Paramecium extracts revealed that the concentrations of K+ and Mg2+ in nonsymbiotic Paramecium extracts were too low to enhance symbiotic algal carbon fixation, suggesting that symbiotic P. bursaria provide suitable cation conditions for photosynthesis to its symbiotic Chlorella.

Phylogenetically close group I introns with different positions among Paramecium bursaria photobionts imply a primitive stage of intron diversification.

Group I introns are a distinct RNA group that catalyze their excision from precursor RNA transcripts and ligate the exons. Group I introns have a sporadic and highly biased distribution due to the two intron transfer mechanisms of homing and reverse splicing. These transfer pathways recognize assigned sequences even when introns are transferred beyond the species level. Consequently, introns at homologous gene sites between different host organisms are more related than those at heterologous sites within an organism. We describe the subgroup IE introns of two Chlorella species that are symbiotic green algae (photobionts) of a ciliate, Paramecium bursaria. One strain Chlorella sp. SW1-ZK (Csw.) had two IE introns at S651 and L2449, and the other strain Chlorella sp. OK1-ZK (Cok.) had four IE introns at S943, L1688, L1926, and L2184 (numbering reflects their homologous position in Escherichia coli rRNA gene: S = small subunit rRNA, L = large subunit rRNA). Despite locating on six heterologous sites, the introns formed a monophyletic clade independent of other groups. Phylogenetic and structural analyses of the introns indicated that Csw.L2449 has an archaic state, and the other introns are assumed to be originated from this intron. Some of the introns shared common internal guide sequences, which are necessary for misdirected transfer (i.e., transposition) via reverse splicing. Other introns, however, shared similar sequence fragments further upstream, after the insertions. We propose a hypothetical model to explain how these intron transpositions may have occurred in these photobionts; they transposed by a combination of homing-like event requiring relaxed sequence homology of recognition sequences and reverse splicing. This case study may represent a key to describe how group I intron explores new insertion sites.

Isolation and characterization of a virus (CvV-BW1) that infects symbiotic algae of Paramecium bursaria in Lake Biwa, Japan.

BACKGROUND: We performed an environmental study of viruses infecting the symbiotic single-celled algae of Paramecium bursaria (Paramecium bursaria Chlorella virus, PBCV) in Lake Biwa, the largest lake in Japan. The viruses detected were all Chlorella variabilis virus (CvV = NC64A virus). One of them, designated CvV-BW1, was subjected to further characterization. RESULTS: CvV-BW1 formed small plaques and had a linear DNA genome of 370 kb, as judged by pulsed-field gel electrophoresis. Restriction analysis indicated that CvV-BW1 DNA belongs to group H, one of the most resistant groups among CvV DNAs. Based on a phylogenetic tree constructed using the dnapol gene, CvV was classified into two clades, A and B. CvV-BW1 belonged to clade B, in contrast to all previously identified virus strains of group H that belonged to clade A. CONCLUSIONS: We conclude that CvV-BW1 composes a distinct species within C. variabilis virus.

Synthesis and structure-activity relationship of botryllamides that block the ABCG2 multidrug transporter.

In previous work, botryllamides discovered from the marine ascidian Botryllus tyreus were characterized as selective inhibitors of the ABCG2 multidrug transporter. However, the structural basis for this activity could not be established. In this study, botryllamide F, the core botryllamide structure, and botryllamide G, the most potent botryllamide ABCG2 inhibitor, were synthesized along with a series of structural variants for evaluation of structure-activity relationships. The biological activity of synthetic botryllamide analogs implied that the 2-methoxy-p-coumaric acid portion, and the degree of double bond conjugation within this group, were critical for inhibition of ABCG2. However, variations in the substituents on the two aryl groups did not appear to significantly impact the potency or degree of inhibition.

Oridamycins A and B, anti-Saprolegnia parasitica indolosesquiterpenes isolated from Streptomyces sp. KS84.

Oridamycins A (1) and B (2) were isolated from the fermentation broth of Streptomyces sp. strain KS84 as selective anti-Saprolegnia parasitica antibiotics. Their structures were elucidated as pentacyclic indolosesquiterpenes by the combination of NMR and spectroscopic analyses. The absolute configuration of 1 was determined by ROESY analyses after the advanced Mosher analysis. Compound 1 exhibited anti-S. parasitica activity with an MIC value of 3.0 microg/mL, but was much less active against the phytopathogenic fungus Phoma sp. and the yeast Saccharomyces cerevisiae.

Multiple origins of the symbioses in Paramecium bursaria.

Many organisms have symbioses with photosynthetic algae as typified by corals, clams, lichens, and some protozoa. Paramecium bursaria contains green algal symbionts and this unicellular ciliate is a textbook example used for microscopic observation in junior high school science projects. We have determined molecular phylogenies for the green algal symbionts. The symbiotic algae are the main constituent of the Paramecium cytoplasm, and we have recognized a total of four species, of which two were newly discovered in the present study. One should be regarded genetically as Chlorella vulgaris, and it belongs phylogenetically to the Chlorella clade (Chlorellaceae, Trebouxiophyceae) as well as "American" and "European" groups, which we previously introduced. Their genetic dissimilarities are 0.50-0.83% in 18S rDNA comparisons, but those of the internal transcribed spacer 2 (ITS2) reach an unambiguous level (22.6-26.6%). These dissimilarities suggest that they are equivalent to discrete species derived from multiple origins as paramecian symbionts. Another newcomer was clearly separated from the Chlorellaceae, and this alga clustered with Coccomyxa spp. in ITS2 analyses. These symbiotic relations indicate multiple origins of symbionts.

Effect of sugars on amino acid transport by symbiotic Chlorella.

Symbiotic Chlorella F36-ZK isolated from Paramecium bursaria F36 has constitutive amino acid transport systems, whereas free-living Chlorella does not. We found that in symbiotic algae, the rate of serine (Ser) uptake increased in the presence of glucose (Glc) and non-metabolisable analogues, whilst incorporation of Ser into protein was not affected. The activation did not involve new protein synthesis and was enhanced under alkaline conditions. An increase in the rate of Ser transport resulted from Glc treatment even when pulsed for only 1 min at low concentrations (EC(50)=3 microM). No uptake of Glc itself was observed in F36-ZK. Thus, the transport signal appears to be transmitted via a glucose sensing and signalling pathway. Many Glc-related compounds also increased the rate of Ser uptake without an additive effect, suggesting recognition of these sugars by the same receptor and providing some insight into features of the structure-activity relationship. Ser uptake by F36-ZK is inhibited by Ca(2+), which is typically considered to be a positive modulator of amino acid uptake. Given that Glc restored Ser uptake from inhibition by Ca(2+), we propose that this compound is possibly involved in regulation of amino acid transport in this symbiotic relationship.

Induction of Maltose Release by Light in the Endosymbiont Chlorella variabilis of Paramecium bursaria.

The endosymbiotic green algae of Paramecium bursaria are known to release a photosynthate to the host cells. The endosymbiont Chlorella variabilis F36-ZK isolated in Japan releases maltose under acidic conditions, and such release requires both light and low pH. However, whether photosynthate release is due to light sensing by photoreceptors or is merely a consequence of active photosynthesis is unclear. Herein, we studied the effect of light on maltose release from C. variabilis F36-ZK; we measured maltose release using a combination of 1-phenyl-3-methyl-5-pyrazolone derivative and 14C-tracer methods. Blue (450nm) or red (around 600nm) light was most effective to stimulate maltose release. This suggests that the photosynthetic pathway probably participates in maltose release, because the effective wavelength corresponds to the absorption spectrum of chlorophyll. Furthermore, maltose release was slightly affected by addition of a photosynthetic inhibitor, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, but was abolished by another inhibitor of photosynthesis, 2,5-dibromo-6-isopropyl-3-methyl-1,4-benzoquinone, suggesting that electron flow through photosystem I may be more involved in maltose release. Interestingly, starving F36-ZK cells cultured under prolonged dark conditions did not release maltose but retained their photosynthetic capacity. Our results thus show that maltose release is regulated by light and cellular conditions in endosymbiotic Chlorella.

Malignant diseases of hematopoietic and lymphoid tissues in Chernobyl clean-up workers.

INTRODUCTION: The question as to whether the incidence of leukemias and malignant lymphomas among the clean-up workers increased in 18 years after the catastrophe is still a point of much controversy. Precise diagnosis of the main forms of hematopoietic malignancies and comparison of these data with those in the general population will be helpful in estimating thr relative contribution of the radiation factor to the overall incidence of such pathologies. MATERIALS AND METHODS: In all, 187 consecutive cases of malignant diseases of hematopoietic and lymphoid tissues in Chernobyl clean-up workers were analyzed in Ukrainian Reference Laboratory in 1996-2003. A total of 1942 consecutive patients of general population, mainly the residents of Kyiv city and district, diagnosed in References Laboratory at the same period comprised the group of comparison. The morphology and cytochemistry of bone marrow and peripheral blood cells were studied. Immunocytochemical techniques (PAP, APAAP, ABC) and the panel of monoclonal antibodies to differentiation antigens of leukocytes were employed for immunophenotyping leukemic cells. RESULTS: Various types of malignant disease of hematopoietic and lymphoid tissues were registered in Chernobyl clean-up workers under study including myelodysplastic syndromes (nine patients), acute lymphoblastic leukemia (eight) and acute myeloblastic leukemia (31), chromic myeloid leukemia (17), multiple myeloma (17) and other forms of chromic myeloproliferative and lymphoproliferative disease including B-cell chromic lymphocytic leukemia (49 patients). CONCLUSION: The verified diagnosis of tumors of hematopoietic malignancies according to modern classification (EGIL, WHO) could be the prerequisite for further analytical epidemiology study of leukemias that may be related to the Chernobyl accident.

Cineromycin B isolated from Streptomyces cinerochromogenes inhibits adipocyte differentiation of 3T3-L1 cells via Krüppel-like factors 2 and 3.

AIMS: 3T3-L1 cells are preadipocytes and often used as a model for cellular differentiation to adipocytes; however, the mechanism of this differentiation is not completely understood even in these model cells. In this study, we sought to identify a unique anti-adipogenesis agent from microorganisms and to examine its mechanism of action to gain knowledge and create a tool and/or seed compound for anti-obesity drug discovery research. MAIN METHOD: Screening for anti-adipogenesis agents from microorganisms was performed using a 3T3-L1 cell differentiation system, and an active compound was isolated. The inhibitory mechanism of the compound was investigated by measuring the expression of key regulators using quantitative real-time PCR and Western blot analysis. KEY FINDINGS: The compound with anti-adipogenic activity in 3T3-L1 cells was identified as cineromycin B. Cineromycin B at 50 µg/mL suppressed intracellular lipid accumulation and the expression of peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer binding protein alpha (C/EBPα), which are master regulators of adipocyte differentiation. Further investigations showed that cineromycin B increased significantly the mRNA expression of two negative regulators of adipocyte differentiation, Krüppel-like factor (KLF) 2 and KLF3, at an early stage of the differentiation. The results of siRNA transfection experiments indicated that cineromycin B is a unique adipocyte differentiation inhibitor, acting mainly via upregulation of KLF2 and KLF3, and these KLFs may play a role in the early stage of differentiation. SIGNIFICANCE: Cineromycin B inhibited adipocyte differentiation in 3T3-L1 cells mainly via upregulation of KLF2 and KLF3 mRNA expression at an early stage of the differentiation.

Action mechanism of a selective anti-cyanobacterial compound, argimicin A.

Argimicin A is a potent anti-cyanobacterial compound produced by one of algae-lysing bacteria, Sphingomonas sp. M-17. Since the compound seemed to exhibit selective activities against cyanobacteria and such selectivity were considered to be quite rare, the mode of action of argimicin A was investigated. Argimicin A showed a unique delayed action, i.e., the cyanobacterial cell division continued until at least 36 hours treatment even though the decrement of oxygen evolution has been observed at 24 hours treatment. The compound is concluded to be a photosynthetic inhibitor which interrupts electron transport chain prior to photosystem II. From the preliminary fluorescent spectrum of argimicin A treated cyanobacterial cells, the site of action was speculated to be photo energy transfer from a cyanobacterial specific complex of accessory protein pigments, phycobilisome, to photosystem II.

[Drug-resistant B cell chronic lymphocytic leukemia safely treated with rituximab to control leukemic cell increment and platelet transfusion dependence].

A 61-year-old man was found to have mild lymphocytosis during a medical checkup and was referred to our hospital in 1993. Physical examination showed a mild hepatomegaly, and bone marrow examination revealed the proliferation of monoclonal mature B cells. He was diagnosed with B-CLL. Chlorambucil and then fludarabine were effective initially. However, large transformed cells started to increase in 2000, and the increment became uncontrollable and platelet transfusion dependence developed. He was admitted to our hospital in October 2001. He intermittently received a total of 32 administrations of rituximab. The total dose was 15, 500 mg. The toxicity was tolerable and he became transfusion independent for 6 months. However, systemic lymphoadenopathy and hepatomegaly did not respond to the drug. We conclude that rituximab treatment is useful for refractory B-CLL because of its excellent safety.

Saprolmycins A-E, new angucycline antibiotics active against Saprolegnia parasitica.

Saprolmycins A-E, five new anti-Saprolegnia parasitica antibiotics were isolated from the culture broth of Streptomyces sp. strain TK08046. As determined using a combination of NMR and spectroscopic analyses, the structures of these compounds were elucidated as a new group of angucycline compounds closely related to saquayamycin. Saprolmycin A and E exhibited potent anti-S. parasitica selective activities, with MIC values of 3.9 and 7.8 ng ml(-1), respectively, but weak or no activity against fungi, gram-positive or -negative bacteria, and microalgae or zooplankton. Our results suggest these two compounds as highly effective and environmentally safe anti-saprolegniasis candidates.

Microbulbifer variabilis sp. nov. and Microbulbifer epialgicus sp. nov., isolated from Pacific marine algae, possess a rod-coccus cell cycle in association with the growth phase.

Phylogenetic and taxonomic characterization was performed for 14 strains of bacteria that produce anticancer antibiotics (pelagiomicins) (represented by strain Ni-2088(T)) and one strain that produces UV-absorbing substances (strain F-104(T)), isolated from marine algae and seagrass collected from coastal areas of tropical Pacific islands and a subtropical island of Japan. All 15 isolates were Gram-negative, strictly aerobic, non-motile and non-spore-forming. Sequence analysis of the 16S rRNA gene showed that the isolates occupied positions in the phylogenetic radiation of the genus Microbulbifer, with similarities of 93.6-97.6 %. The cells possessed a clearly discernible rod-coccus cell cycle in association with the growth phase; cells were rods during the growth phase and all converted to coccoid-ovoid cells when proliferation ceased. The coccoid-ovoid cells were optically denser than the rod cells and were viable for extended periods. They were considered to constitute a resting form. The type strains of described species of Microbulbifer were also found to possess identical rod-coccus cell cycles. The G+C content of the DNA was 48.1-49.7 mol%. The major respiratory quinone system was ubiquinone-8. The major fatty acids were C(18 : 1)omega7c and C(16 : 0), and the hydroxy acids comprised C(10 : 0) 3-OH, C(12 : 0) 3-OH and iso-C(11 : 0) 3-OH. The polar lipids comprised phosphatidylethanolamine, phosphatidylglycerol and phosphatidylserine. The group of 14 pelagiomicin-producing strains and strain F-104(T) each constituted a single genomic species. Based on phylogenetic affiliation, phenotypic characteristics and genomic distinctness, the isolates represent two novel species in the genus Microbulbifer, for which the names Microbulbifer variabilis sp. nov. (type strain Ni-2088(T) =MBIC01082(T) =ATCC 700307(T)) and Microbulbifer epialgicus sp. nov. (type strain F-104(T) =MBIC03330(T) =DSM 18651(T)) are proposed.