Project description:Here, we report the draft genome sequence of strain NBRC 16556, deposited as Streptomyces hygroscopicus subsp. hygroscopicus into the NBRC culture collection. An average nucleotide identity analysis confirmed that the taxonomic identification is correct. The genome sequence will serve as a valuable reference for genome mining to search new secondary metabolites.
Project description:Chromomycin A3 is an antitumor drug produced by Streptomyces griseus subsp. griseus. It consists of a tricyclic aglycone with two aliphatic side chains and two O-glycosidically linked saccharide chains, a disaccharide of 4-O-acetyl-D-oliose (sugar A) and 4-O-methyl-D-oliose (sugar B), and a trisaccharide of D-olivose (sugar C), D-olivose (sugar D), and 4-O-acetyl-L-chromose B (sugar E). The chromomycin gene cluster contains four glycosyltransferase genes (cmmGI, cmmGII, cmmGIII, and cmmGIV), which were independently inactivated through gene replacement, generating mutants C60GI, C10GII, C10GIII, and C10GIV. Mutants C10GIV and C10GIII produced the known compounds premithramycinone and premithramycin A1, respectively, indicating the involvement of CmmGIV and CmmGIII in the sequential transfer of sugars C and D and possibly also of sugar E of the trisaccharide chain, to the 12a position of the tetracyclic intermediate premithramycinone. Mutant C10GII produced two new tetracyclic compounds lacking the disaccharide chain at the 8 position, named prechromomycin A3 and prechromomycin A2. All three compounds accumulated by mutant C60GI were tricyclic and lacked sugar B of the disaccharide chain, and they were named prechromomycin A4, 4A-O-deacetyl-3A-O-acetyl-prechromomycin A4, and 3A-O-acetyl-prechromomycin A4. CmmGII and CmmGI are therefore responsible for the formation of the disaccharide chain by incorporating, in a sequential manner, two D-oliosyl residues to the 8 position of the biosynthetic intermediate prechromomycin A3. A biosynthetic pathway is proposed for the glycosylation events in chromomycin A3 biosynthesis.
Project description:UV irradiation of Streptomyces griseus 2247 yielded a new chromosomal deletion mutant, MM9. Restriction and sequencing analysis revealed that homologous recombination between two similar lipoprotein-like open reading frames, which are located 450 and 250 kb from the left and right ends, respectively, caused chromosomal arm replacement. As a result, new 450-kb terminal inverted repeats (TIRs) were formed in place of the original 24-kb TIRs. Frequent homologous recombinations in Streptomyces strains suggest that telomere deletions can usually be repaired by recombinational DNA repair functioning between the intact and deleted TIR sequences on the same chromosome.
Project description:In Streptomyces griseus, A-factor (2-isocapryloyl-3R-hydroxymethyl-gamma-butyrolactone) serves as a microbial hormone that switches on many genes required for streptomycin production and morphological development. An open reading frame (Orf1) showing high sequence similarity to oligoribonucleases of various origins is present just downstream of adpA, one of the A-factor-dependent genes. Orf1 was named OrnA (oligoribonuclease A) because it showed 3'-to-5' exo-oligoribonuclease activity, releasing [(32)P]CMP from ApCpC[(32)P]pC used as a substrate. Reverse transcription-PCR and S1 nuclease mapping analyses revealed that ornA was transcribed from two promoters; one was a developmentally regulated, A-factor-dependent promoter in front of adpA, and the other was a constitutive promoter in front of the ornA coding sequence. Transcription of ornA was thus additively enhanced at the initiation stage for secondary metabolism and aerial mycelium formation. ornA-disrupted strains grew slowly and scarcely formed aerial mycelium. ornA homologues were distributed in a wide variety of Streptomyces species, including S. coelicolor A3(2), as determined by Southern hybridization analysis. Disruption of the ornA homologue in S. coelicolor A3(2) also caused phenotypes similar to those of the S. griseus DeltaornA strains. The OrnA oligoribonucleases in Streptomyces species are therefore not essential but play an important role in vegetative growth and in the initiation of differentiation.
Project description:We performed ribosome profiling which is the deep-sequencing of mRNA fragments protected by translating ribosome for two Streptomyces species through different growth phases to provide the translatome data