Authors: Thomas A Richards, Nicholas J Talbot

What do you do when your food is too big to chew, or worse, when you don't have a stomach at all? Richards and Talbot explain how osmotrophs get around the problem by digesting on the outside.

Topics: Eating; Feeding Behavior; Fungi; Microbial Interactions; Oomycetes; Streptomycetaceae

PubMed: 30352181
DOI: 10.1016/j.cub.2018.07.069

Authors: Qinqin Zhao, Savannah Bertolli, Young-Jun Park...

Streptomyces are a genus of ubiquitous soil bacteria from which the majority of clinically utilized antibiotics derive. The production of these antibacterial molecules reflects the relentless competition Streptomyces engage in with other bacteria, including other Streptomyces species. Here we show that in addition to small-molecule antibiotics, Streptomyces produce and secrete antibacterial protein complexes that feature a large, degenerate repeat-containing polymorphic toxin protein. A cryo-electron microscopy structure of these particles reveals an extended stalk topped by a ringed crown comprising the toxin repeats scaffolding five lectin-tipped spokes, which led us to name them umbrella particles. Streptomyces coelicolor encodes three umbrella particles with distinct toxin and lectin composition. Notably, supernatant containing these toxins specifically and potently inhibits the growth of select Streptomyces species from among a diverse collection of bacteria screened. For one target, Streptomyces griseus, inhibition relies on a single toxin and that intoxication manifests as rapid cessation of vegetative hyphal growth. Our data show that Streptomyces umbrella particles mediate competition among vegetative mycelia of related species, a function distinct from small-molecule antibiotics, which are produced at the onset of reproductive growth and act broadly. Sequence analyses suggest that this role of umbrella particles extends beyond Streptomyces, as we identified umbrella loci in nearly 1,000 species across Actinobacteria.

Topics: Anti-Bacterial Agents; Antibiosis; Bacterial Proteins; Bacterial Toxins; Cryoelectron Microscopy; Lectins; Microbial Sensitivity Tests; Models, Molecular; Streptomyces; Streptomyces coelicolor; Streptomyces griseus

PubMed: 38632398
DOI: 10.1038/s41586-024-07298-z

Authors: Vineetha M Zacharia, Matthew F Traxler

bacteria employ a newly-discovered cell type, the "explorer" cell, to rapidly colonize new areas in the face of competition.

Topics: Fungi; Streptomyces

PubMed: 28051767
DOI: 10.7554/eLife.23624

Authors: Elaine-Jinfeng Chin, Kuan-Chieh Ching, Zann Y Tan...

Natural products have long been used as a source of antimicrobial agents against various microorganisms. Actinobacteria are a group of bacteria best known to produce a wide variety of bioactive secondary metabolites, including many antimicrobial agents. In this study, four actinobacterial strains found in Singapore terrestrial soil were investigated as potential sources of new antimicrobial compounds. Large-scale cultivation, chemical, and biological investigation led to the isolation of a previously undescribed tetronomycin A () that demonstrated inhibitory activities against both Gram-positive bacteria (SA) and methicillin-resistant (MRSA) (i.e., MIC of 2-4 μM and MBC of 9-12 μM), and several known antimicrobial compounds, namely nonactin, monactin, dinactin, 4E-deacetylchromomycin A3, chromomycin A2, soyasaponin II, lysolipin I, tetronomycin, and naphthomevalin. Tetronomycin showed a two- to six-fold increase in antibacterial activity (i.e., MIC and MBC of 1-2 μM) as compared to tetronomycin A (), indicating the presence of an oxy-methyl group at the C-27 position is important for antibacterial activity.

Topics: Methicillin-Resistant Staphylococcus aureus; Streptomycetaceae; Biological Products; Singapore; Microbial Sensitivity Tests; Anti-Bacterial Agents; Anti-Infective Agents; Bacteria

PubMed: 37570802
DOI: 10.3390/molecules28155832

Review

Authors: Ricardo Sánchez de la Nieta, Ramón I Santamaría, Margarita Díaz...

Bacteria of the genus constitute an authentic biotech gold mine thanks to their ability to produce a myriad of compounds and enzymes of great interest at various clinical, agricultural, and industrial levels. Understanding the physiology of these organisms and revealing their regulatory mechanisms is essential for their manipulation and application. Two-component systems (TCSs) constitute the predominant signal transduction mechanism in prokaryotes, and can detect a multitude of external and internal stimuli and trigger the appropriate cellular responses for adapting to diverse environmental conditions. These global regulatory systems usually coordinate various biological processes for the maintenance of homeostasis and proper cell function. Here, we review the multiple TCSs described and characterized in , one of the most studied and important model species within this bacterial group. TCSs are involved in all cellular processes; hence, unravelling the complex regulatory network they form is essential for their potential biotechnological application.

Topics: Streptomyces coelicolor; Bacterial Proteins; Streptomyces; Signal Transduction; Gene Expression Regulation, Bacterial

PubMed: 36499414
DOI: 10.3390/ijms232315085

Review

Authors: Márió Gajdács

The emergence and spread of antibiotic-resistant pathogens is a major public health issue, which requires global action of an intersectoral nature. Multidrug-resistant (MDR) pathogens-especially "ESKAPE" bacteria-can withstand lethal doses of antibiotics with various chemical structures and mechanisms of action. Pharmaceutical companies are increasingly turning away from participating in the development of new antibiotics, due to the regulatory environment and the financial risks. There is an urgent need for innovation in antibiotic research, as classical discovery platforms (e.g., mining soil ) are no longer viable options. In addition to discovery platforms, a concept of an ideal antibiotic should be postulated, to act as a blueprint for future drugs, and to aid researchers, pharmaceutical companies, and relevant stakeholders in selecting lead compounds. Based on 150 references, the aim of this review is to summarize current advances regarding the challenges of antibiotic drug discovery and the specific attributes of an ideal antibacterial drug (a prodrug or generally reactive compound with no specific target, broad-spectrum antibacterial activity, adequate penetration through the Gram-negative cell wall, activity in biofilms and in hard-to-treat infections, accumulation in macrophages, availability for oral administration, and for use in sensitive patient groups).

Topics: Anti-Bacterial Agents; Biofilms; Drug Design; Drug Discovery; Drug Resistance, Multiple, Bacterial; Humans; Streptomycetaceae

PubMed: 30832456
DOI: 10.3390/molecules24050892

Authors: Hoda Jaffal, Mounia Kortebi, Pauline Misson...

Streptomyces are renowned for their prolific production of specialized metabolites with applications in medicine and agriculture. These multicellular bacteria present a sophisticated developmental cycle and play a key role in soil ecology. Little is known about the impact of Streptomyces phage on bacterial physiology. In this study, we investigated the conditions governing the expression and production of "Samy", a prophage found in Streptomyces ambofaciens ATCC 23877. This siphoprophage is produced simultaneously with the activation of other mobile genetic elements. Remarkably, the presence and production of Samy increases bacterial dispersal under in vitro stress conditions. Altogether, this study unveiled a new property of a bacteriophage infection in the context of multicellular aggregate dynamics.

Topics: Streptomyces; Prophages; Virus Activation

PubMed: 39052683
DOI: 10.1371/journal.pbio.3002725

Authors: David P Labeda, Christopher A Dunlap, Xiaoying Rong...

The family Streptomycetaceae, notably species in the genus Streptomyces, have long been the subject of investigation due to their well-known ability to produce secondary metabolites. The emergence of drug resistant pathogens and the relative ease of producing genome sequences has renewed the importance of Streptomyces as producers of new natural products and resulted in revived efforts in isolating and describing strains from novel environments. A previous large study of the phylogeny in the Streptomycetaceae based on 16S rRNA gene sequences provided a useful framework for the relationships among species, but did not always have sufficient resolution to provide definitive identification. Multi-locus sequence analysis of 5 house-keeping genes has been shown to provide improved taxonomic resolution of Streptomyces species in a number of previous reports so a comprehensive study was undertaken to evaluate evolutionary relationships among species within the family Streptomycetaceae where type strains are available in the ARS Culture Collection or genome sequences are available in GenBank. The results of the analysis supported the distinctiveness of Kitasatospora and Streptacidiphilus as validly named genera since they cluster outside of the phylogenetic radiation of the genus Streptomyces. There is also support for the transfer of a number of Streptomyces species to the genus Kitasatospora as well for reducing at least 31 species clusters to a single taxon. The multi-locus sequence database resulting from the study is a useful tool for identification of new isolates and the phylogenetic analysis presented also provides a road map for planning future genome sequencing efforts in the Streptomycetaceae.

Topics: Base Sequence; DNA, Bacterial; DNA, Ribosomal; Genes, Essential; Multilocus Sequence Typing; Phylogeny; Sequence Analysis, DNA; Streptomyces

PubMed: 28039547
DOI: 10.1007/s10482-016-0824-0

Review

Authors: Corrie V Vincent, Dawn R D Bignell

have a uniquely complex developmental life cycle that involves the coordination of morphological differentiation with the production of numerous bioactive specialized metabolites. The majority of spp. are soil-dwelling saprophytes, while plant pathogenicity is a rare attribute among members of this genus Phytopathogenic are responsible for economically important diseases such as common scab, which affects potato and other root crops. Following the acquisition of genes encoding virulence factors, pathogens are expected to have specifically adapted their regulatory pathways to enable transition from a primarily saprophytic to a pathogenic lifestyle. Investigations of the regulation of pathogenesis have primarily focused on and the principal pathogenicity determinant thaxtomin A. The coordination of growth and thaxtomin A production in this species is controlled in a hierarchical manner by cluster-situated regulators, pleiotropic regulators, signalling and plant-derived molecules, and nutrients. Although the majority of phytopathogenic produce thaxtomins, many also produce additional virulence factors, and there are scab-causing pathogens that do not produce thaxtomins. The development of effective control strategies for common scab and other plant diseases requires a more in-depth understanding of the genetic and environmental factors that modulate the plant pathogenic lifestyle of these organisms.

Topics: Streptomyces; Plant Diseases; Virulence; Virulence Factors; Gene Expression Regulation, Bacterial; Bacterial Proteins; Plants; Solanum tuberosum; Indoles; Piperazines

PubMed: 38190652
DOI: 10.1139/cjm-2023-0171

Review

Authors: Joseph R McCormick, Klas Flärdh

Streptomyces coelicolor is the genetically best characterized species of a populous genus belonging to the gram-positive Actinobacteria. Streptomycetes are filamentous soil organisms, well known for the production of a plethora of biologically active secondary metabolic compounds. The Streptomyces developmental life cycle is uniquely complex and involves coordinated multicellular development with both physiological and morphological differentiation of several cell types, culminating in the production of secondary metabolites and dispersal of mature spores. This review presents a current appreciation of the signaling mechanisms used to orchestrate the decision to undergo morphological differentiation, and the regulators and regulatory networks that direct the intriguing development of multigenomic hyphae first to form specialized aerial hyphae and then to convert them into chains of dormant spores. This current view of S. coelicolor development is destined for rapid evolution as data from '-omics' studies shed light on gene regulatory networks, new genetic screens identify hitherto unknown players, and the resolution of our insights into the underlying cell biological processes steadily improve.

Topics: Gene Expression Regulation, Bacterial; Hyphae; Signal Transduction; Spores, Bacterial; Streptomyces coelicolor

PubMed: 22092088
DOI: 10.1111/j.1574-6976.2011.00317.x