Contractile injection systems facilitate sporogenic differentiation of Streptomyces davawensis through the action of a phage tapemeasure protein-related effector.

Contractile injection systems (CISs) are prokaryotic phage tail-like nanostructures loading effector proteins that mediate various biological processes. Although CIS functions have been diversified through evolution and hold the great potential as protein delivery systems, the functional characterisation of CISs and their effectors is currently limited to a few CIS lineages. Here, we show that the CISs of Streptomyces davawensis belong to a unique group of bacterial CISs distributed across distant phyla and facilitate sporogenic differentiation of this bacterium.

An Enzyme Assay Kit for GABA Quantification in Plant Tissues.

Gamma-aminobutyric acid (GABA) is an amino acid that has a role as a signaling molecule. In plants, its involvement in stress responses is widely investigated. A newly developed method of quantification of GABA is described in this chapter.

Intracellular Phage Tail-Like Nanostructures Affect Susceptibility of Streptomyces lividans to Osmotic Stress.

Contractile injection systems (CISs) are a large group of phage tail-like nanostructures conserved among bacteria. Despite their wide distribution, the biological significance of CISs in bacteria remains largely unclear except for a few unicellular bacteria. Here, we show that Streptomyces lividans-a model organism of filamentous Gram-positive bacteria with highly conserved CIS-related gene clusters-produces intracellular CIS-like nanostructures ( phage tail-like particles [SLPs]) that affect phenotypes of this bacterium under hyperosmotic conditions.

Characterization of 5'-nucleotidases secreted from Streptomyces.

To study the ability of Streptomyces to utilize environmental nucleotides, we screened for strains exhibiting extracellular 5'-inosine monophosphate (IMP)-dephosphorylating activity in our collection of soil isolates and obtained two producers: NE5-10 and Y2F8-2. The enzyme responsible for the activity was purified from the culture supernatant of each strain, and its mass spectral data were used to identify the coding sequence. The gene was successfully identified in the whole genome sequence of each strain; it was located in a conserved gene cluster of phosphate-related functions and encoded an approximately 600-amino acid long protein containing an N-terminal secretion signal.

Organocatalytic activity of granaticin and its involvement in bactericidal function.

We previously discovered that actinorhodin, a benzoisochromanequinone antibiotic produced by Streptomyces coelicolor A3(2), serves as a catalyst facilitating the oxidation of ascorbic acid and cysteine (PNAS 48:17,152, 2014). In the present study, we screened for similar ascorbic acid-oxidizing activity in the culture broth of various Streptomyces spp., and discovered marked activity in the culture broth of Streptomyces vietnamensis.

GABA enzymatic assay kit.

We developed an enzymatic assay system enabling easy quantification of 4-aminobutyric acid (GABA). The reaction of GABA aminotransferase obtained from NBRC 13977 was combined to those of the previously developed glutamate assay system using glutamate oxidase and peroxidase. The three-enzyme system allowing GABA-dependent dye formation due to the oxidative coupling between 4-aminoantipyrine and Trinder's reagent enabled accurate quantification of 0.

Extracytoplasmic diaphorase activity of Streptomyces coelicolor A3(2).

Metabolism and utilization of plant-derived aromatic substances are fundamental to the saprophytic growth of Streptomyces. Here, we studied an enzyme activity reducing 2,6-dichlorophenolindophenol and nitroblue tetrazolium in the culture supernatant of Streptomyces coelicolor A3(2). N-terminal amino acid sequencing of a nitroblue tetrazolium-reducing enzyme revealed that the enzyme corresponds to the SCO2180 product.

Developmental defect of cytochrome oxidase mutants of Streptomyces coelicolor A3(2).

To study the link between energy metabolism and secondary metabolism/morphological development in Streptomyces, knockout mutants were generated with regard to the subunits of the cytochrome oxidase supercomplex (CcO) in Streptomyces coelicolor A3(2). All mutants exhibited an identical phenotype: viable but defective in antibiotic production and cell differentiation when grown in both complex and minimal media. The growth yield of the CcO mutant was about half of that of the WT strain on glucose medium while both strains grew similarly on maltose medium.

Streptomyces metabolites in divergent microbial interactions.

Streptomyces and related bacteria produce a wide variety of secondary metabolites. Of these, many compounds have industrial applications, but the question of why this group of microorganism produces such various kinds of biologically active substances has not yet been clearly answered. Here, we overview the results from our studies on the novel function and role of Streptomyces metabolites.

Natural low-molecular mass organic compounds with oxidase activity as organocatalysts.

Organocatalysts, low-molecular mass organic compounds composed of nonmetallic elements, are often used in organic synthesis, but there have been no reports of organocatalysts of biological origin that function in vivo. Here, we report that actinorhodin (ACT), a natural product derived from Streptomyces coelicolor A3(2), acts as a biocatalyst. We purified ACT and assayed its catalytic activity in the oxidation of L-ascorbic acid and L-cysteine as substrates by analytical methods for enzymes.