Streptomyces is the largest antibiotic-producing genus in the microbial world. Manumycin-type antibiotics are a small group of its metabolites. Their antibiotic activities are not very important but they show biological properties which can be potencially used e. g. to treat inflammation, cancer or Alzheimer's disease. The structure of manumycin compounds is formed by a central unit with connected upper and lower polyketide chain. The lower chain is mostly terminated by so called C5N unit. The substance U-62162 produced by the strain Streptomyces verdensis differs significantly from the other members of the manumycin-type metabolites in the structure of the lower chain which is fully saturated and lacking the C5N unit. The U-62162 biosynthetic gene cluster was sequenced and functions of identified open reading frames were deduced. Heterologous expressions of the cluster showed some genes reguired for the biosynthesis of the upper chain to be encoded on a different part of the chromosome. The insertional inactivation of the vrdER gene confirmed the enoylreductase to be responsible for the saturation of the lower chain. DSBA oxidoreductase, which gene is located at the edge of the cluster, is probably not involved in the biosynthesis. The insertion of genes for the biosynthesis of the C5N unit did...

1 Abstract: Secondary metabolism of Gram-positive soil bacteria from the genus Streptomyces is a inestimable source of natural products including manumycins, which belong to a polyketide group. These products possess weak antimicrobial, but important antiinflammatory, and antitumor activities. Streptomyces sp. offers broad amounts of yet undiscovered antibiotics, potentially utilizable in clinical medicine. This fact makes out of these organisms a promising solution to our present problem with rising antibiotic resistance among microorganisms. Two main ways are applied in this research: There are efforts of prepairing new derivates based on known products and creating various modifications in their structure. Next, new producers are discovered by "genome mining" methods, activation of silent gene clusters, followed by improvements of antibiotic production. One of those silent clusters was found in the Saccharothrix espanaensis DSM44229 strain. The genetic information has been transferred to a heterologous host in order to characterize its product. Cluster activation and production of novel manumycin-type metabolites occurred in the host after the transfer.

Manumycin antibiotics represent an important class of secondary metabolites produced by Streptomyces bacteria. They belong to a big class of polyketide metabolites and posses significant antimicrobial, anti-inflammatory, antitumor, and many other biological activities. They are characterized by two short polyketide chains, which are attached to a central subunit. Polyketide chains are synthesized by enzymes of the iterative type II polyketide-synthase. Mechanism of regulation of the polyketide chains length has not been known yet. Understanding mechanism can lead to biosynthesis of novel manumycin antibiotics with predetermined chain lengths what may improve their biological activities in favour of a practical use of these compounds. We prepared a mutant strain of asukamycin producer Streptomyces nodosus ssp. asukaensis with deletion of genes coding for type I/II β-ketoacylsynthase and protein AsuC14, which is a potential factor affecting lower polyketide chain length, for the identification of the chain length factor in manumycin antibiotics producers. Next, the genes for type I/II β-ketoacylsynthase and potential chain length-affecting factor C14 from strains producing manumycins with variable length of the lower polyketide chains were expressed in this mutant strain. Our results demonstrate...

Streptomyces are medically important soil-living bacteria that undergo morphological changes from spores to aerial hyphae and are important producers of bioactive compounds including antibiotics. Their gene expression is tightly regulated at the early level of transcription and translation. In the transcriptional control, sigma factors play a central role; the model organism Streptomyces coelicolor possesses astonishing 65 sigma factors. The expression of sigma factors themselves is controlled on the post-transcriptional level through the action of sRNAs that modify their mRNA level. However, only several sigma factors in Streptomyces have known regulons and also their sRNAs-mediated regulation has not been studied so far. According to previously measured gene expression data, we selected several highly expressed sigma factors. Using mutant strains with HA-tagged sigma factors, regulons of two important sigma factors, SigQ and HrdB, were analyzed by ChIP-seq procedure. Other sigma factors were further studied to see if they possess asRNAs, using 5' and 3' RACE method and northern blotting. Our data confirm the essentiality of HrdB sigma factor during the vegetative phase of growth. The other sigma factor, SigQ, has been revealed to be an important regulator of nitrogen metabolism and osmotic...

Streptomyces bacteria are well-known producents of many bioactive metabolites. Its secondary metabolism is a source of many important groups of active compounds that are recently investigated by means of many new methods based on bioinformatic analyses of genome data, modern LC-MS techniques, and metabolic modeling methods. This thesis originates from the genetic screening for a specific gene (als) for cyclizing 5-aminolevulinate synthase. Based on earlier studies, we consider this gene as a genetic tag of the producers of secondary metabolites containing the C5N unit (2-amino-3-hydroxycyklopent- 2-enon). Such metabolites include several groups with variable structures and biological activities, which include manumycins as well. Manumycins are small polyketides with a weak antibiotic aktivity, especially against gram-positive bacteria. However, its cancerostatic and anti-inflammatory effects are of greater importance. Streptomyces monomycini BCCO10 1552 and Streptomyces capoamus BCCO10 1636 strains were found positive for the presence of the als gene in the targeted genetic screening. By the als phylogeny, they cluster near the producents of manumycin compounds. This thesis aimed to determine whether these new natural isolates produce any compounds containing C5N unit, and to characterize them in...

The clinically used antibiotic lincomycin consists of an amino-sugar and an amino-acid moiety. The incorporated amino-acid 4-propyl-L-prolin (PPL) is very important for the linomycin bioactivity, as evidenced by the lower activity of the related antibiotic celesticetin, which incorporates proteinogenic L-prolin instead. Gene clusters for the biosynthesis of both lincosamides are published and reflect a common basis - biosynthesis of amino-sugar precursor and condensation reactions. Additionally, in the biosynthetic gene cluster for lincomycin there is a sub-cluster of genes encoding the biosynthesis of PPL, the alkylated proline derivative (APD). PPL has a common biosynthetic origin with other APDs that are part of the structures of antitumor pyrrolobenzodiazepines and the signal molecule hormaomycin, which is also reflected in the presence of homologous genes in their gene clusters. The acquired knowledge on PPL biosynthesis thus can be applied to a larger group of natural products. The first overall concept of APD biosynthesis was published forty years ago. The milestone was the year 1995 when the gene cluster for lincomycin biosynthesis was published and specific gene products have been proposed for individual biosynthetic steps. The functional proof of proteins has been performed so far just...

Streptomyces, filamentous Gram-positive bacteria are producers of more than 70% of antibiotics used in human therapy and agriculture. They are remarkable because of their complex life cycle (morphological differentiation) which leads to a formation of dormant spores able to survive unfavorable living conditions and allowing long-term survival of the organism. Soil represents their mostly natural living environment. In laboratory conditions they are cultivated in liquid media or on agar. We have developed in our laboratory two phase cultivation system which allows quantitative and reproducible preparation of samples for proteomic, transcriptomic and metabolomic analyses of Streptomycetes differentiation. The system is composed of inert micro- beads submerged in liquid medium. We used two types of micro-beads in our studies, glass and zirconia/silica beads. We followed the surface growth and differentiation of Streptomycetes on both types of beads using optical and electron microscopy (SEM) techniques. We observed major growth and higher antibiotic production on glass beads. Another difference we observed was in size and shape of colonies. In further research, using comparative proteomics, we attempted to identify proteins which might be responsible for recognition and adhesion of Streptomycetes to...