Streptomyces is the largest genus of Actinomycetota, and the type genus of the family Streptomycetaceae. Over 700 species of Streptomyces bacteria have been described. As with the other Actinomycetota, streptomycetes are gram-positive, and have very large genomes with high GC content. Found predominantly in soil and decaying vegetation, most streptomycetes produce spores, and are noted for their distinct "earthy" odor that results from production of a volatile metabolite, geosmin. Different strains of the same species may colonize very diverse environments.
Pseudomonas aeruginosa is a common encapsulated, Gram-negative, aerobic–facultatively anaerobic, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, P. aeruginosa is a multidrug resistant pathogen recognized for its ubiquity, its intrinsically advanced antibiotic resistance mechanisms, and its association with serious illnesses – hospital-acquired infections such as ventilator-associated pneumonia and various sepsis syndromes. P. aeruginosa is able to selectively inhibit various antibiotics from penetrating its outer membrane - and has high resistance to several antibiotics. According to the World Health Organization P. aeruginosa poses one of the greatest threats to humans in terms of antibiotic resistance.
The gene rpoS encodes the sigma factor sigma-38, a 37.8 kD protein in Escherichia coli. Sigma factors are proteins that regulate transcription in bacteria. Sigma factors can be activated in response to different environmental conditions. rpoS is transcribed in late exponential phase, and RpoS is the primary regulator of stationary phase genes. RpoS is a central regulator of the general stress response and operates in both a retroactive and a proactive manner: it not only allows the cell to survive environmental challenges, but it also prepares the cell for subsequent stresses (cross-protection). The transcriptional regulator CsgD is central to biofilm formation, controlling the expression of the curli structural and export proteins, and the diguanylate cyclase, adrA, which indirectly activates cellulose production. The rpoS gene most likely originated in the gammaproteobacteria.
DsrA RNA is a non-coding RNA that regulates both transcription, by overcoming transcriptional silencing by the nucleoid-associated H-NS protein, and translation, by promoting efficient translation of the stress sigma factor, RpoS. These two activities of DsrA can be separated by mutation: the first of three stem-loops of the 85 nucleotide RNA is necessary for RpoS translation but not for anti-H-NS action, while the second stem-loop is essential for antisilencing and less critical for RpoS translation. The third stem-loop, which behaves as a transcription terminator, can be substituted by the trp transcription terminator without loss of either DsrA function. The sequence of the first stem-loop of DsrA is complementary with the upstream leader portion of RpoS messenger RNA, suggesting that pairing of DsrA with the RpoS message might be important for translational regulation. The structures of DsrA and DsrA/rpoS complex were studied by NMR. The study concluded that the sRNA contains a dynamic conformational equilibrium for its second stem–loop which might be an important mechanism for DsrA to regulate the translations of its multiple target mRNAs.
The CsrB RNA is a non-coding RNA that binds to approximately 9 to 10 dimers of the CsrA protein. The CsrB RNAs contain a conserved motif CAGGXXG that is found in up to 18 copies and has been suggested to bind CsrA. The Csr regulatory system has a strong negative regulatory effect on glycogen biosynthesis, glyconeogenesis and glycogen catabolism and a positive regulatory effect on glycolysis. In other bacteria such as Erwinia carotovora the RsmA protein has been shown to regulate the production of virulence determinants, such extracellular enzymes. RsmA binds to RsmB regulatory RNA which is also a member of this family.
RyhB RNA is a 90 nucleotide RNA that down-regulates a set of iron-storage and iron-using proteins when iron is limiting; it is itself negatively regulated by the ferric uptake repressor protein, Fur.
Aminocoumarin is a class of antibiotics that act by an inhibition of the DNA gyrase enzyme involved in the cell division in bacteria. They are derived from Streptomyces species, whose best-known representative – Streptomyces coelicolor – was completely sequenced in 2002. The aminocoumarin antibiotics include:
Streptomyces venezuelae is a species of soil-dwelling Gram-positive bacterium of the genus Streptomyces. S. venezuelae is filamentous. In its spore-bearing stage, hyphae perfuse both above ground as aerial hyphae and in the soil substrate. Chloramphenicol, the first antibiotic to be manufactured synthetically on a large scale, was originally derived from S. venezuelae. Other secondary metabolites produced by S. venezuelae include jadomycin and pikromycin.
mecA is a gene found in bacterial cells which allows them to be resistant to antibiotics such as methicillin, penicillin and other penicillin-like antibiotics.
The IscR stability element is a conserved secondary structure found in the intergenic regions of iscRSUA polycistronic mRNA. This secondary structure prevents the degradation of the iscR mRNA.
Actinorhodin is a benzoisochromanequinone dimer polyketide antibiotic produced by Streptomyces coelicolor. The gene cluster responsible for actinorhodin production contains the biosynthetic enzymes and genes responsible for export of the antibiotic. The antibiotic also has the effect of being a pH indicator due to its pH-dependent color change.
Methylenomycin A is a cyclopentanone derived antibiotic produced by Streptomyces coelicolor A3(2) that is effective against both Gram-negative and Gram-positive bacteria. Methylenomycins are naturally produced in two variants: A and B.
Bacterial small RNAs are small RNAs produced by bacteria; they are 50- to 500-nucleotide non-coding RNA molecules, highly structured and containing several stem-loops. Numerous sRNAs have been identified using both computational analysis and laboratory-based techniques such as Northern blotting, microarrays and RNA-Seq in a number of bacterial species including Escherichia coli, the model pathogen Salmonella, the nitrogen-fixing alphaproteobacterium Sinorhizobium meliloti, marine cyanobacteria, Francisella tularensis, Streptococcus pyogenes, the pathogen Staphylococcus aureus, and the plant pathogen Xanthomonas oryzae pathovar oryzae. Bacterial sRNAs affect how genes are expressed within bacterial cells via interaction with mRNA or protein, and thus can affect a variety of bacterial functions like metabolism, virulence, environmental stress response, and structure.
Rsa RNAs are non-coding RNAs found in the bacterium Staphylococcus aureus. The shared name comes from their discovery, and does not imply homology. Bioinformatics scans identified the 16 Rsa RNA families named RsaA-K and RsaOA-OG. Others, RsaOH-OX, were found thanks to an RNomic approach. Although the RNAs showed varying expression patterns, many of the newly discovered RNAs were shown to be Hfq-independent and most carried a C-rich motif (UCCC).
In molecular biology, the ferric uptake regulator family is a family of bacterial proteins involved in regulating metal ion uptake and in metal homeostasis. The family is named for its founding member, known as the ferric uptake regulator or ferric uptake regulatory protein (Fur). Fur proteins are responsible for controlling the intracellular concentration of iron in many bacteria. Iron is essential for most organisms, but its concentration must be carefully managed over a wide range of environmental conditions; high concentrations can be toxic due to the formation of reactive oxygen species.
Geosmin synthase or germacradienol-geosmin synthase designates a class of bifunctional enzymes that catalyze the conversion of farnesyl diphosphate (FPP) to geosmin, a volatile organic compound known for its earthy smell. The N-terminal half of the protein catalyzes the conversion of farnesyl diphosphate to germacradienol and germacrene D, followed by the C-terminal-mediated conversion of germacradienol to geosmin. The conversion of FPP to geosmin was previously thought to involve multiple enzymes in a biosynthetic pathway.
Streptomyces isolates have yielded the majority of human, animal, and agricultural antibiotics, as well as a number of fundamental chemotherapy medicines. Streptomyces is the largest antibiotic-producing genus of Actinomycetota, producing chemotherapy, antibacterial, antifungal, antiparasitic drugs, and immunosuppressants. Streptomyces isolates are typically initiated with the aerial hyphal formation from the mycelium.
Streptomyces antibioticus is a gram-positive bacterium discovered in 1941 by Nobel-prize-winner Selman Waksman and H. Boyd Woodruff. Its name is derived from the Greek "strepto-" meaning "twisted", alluding to this genus' chain-like spore production, and "antibioticus", referring to this species' extensive antibiotic production. Upon its first characterization, it was noted that S. antibioticus produces a distinct soil odor.
s-SodF RNA is a non-coding RNA (ncRNA) molecule identified in Streptomyces coelicolor. It is produced from sodF mRNA by cleavage of about 90 nucleotides from its 3′UTR. However it does not affect the function of sodF mRNA, but It acts on another mRNA called sodN. s-SodF RNA has a sequence complementary to sodN mRNA from the 5′-end up to the ribosome binding site. It pairs with sodN mRNA, blocks its translation and facilitates sodN mRNA decay. In Streptomyces sodF and sodN genes produce FeSOD and NiSOD superoxide dismutases containing Fe and Ni respectively. Their expression is inversely regulated by nickel-specific Fur-family regulator called Nur. When Ni is present Nur directly represses sodF transcription, and indirectly induces sodN.
Cytochrome P450, family 105, also known as CYP105, is a cytochrome P450 monooxygenase family in bacteria, predominantly found in the phylum Actinomycetota and the order Actinomycetales. The first three genes and subfamilies identified in this family is the herbicide-inducible P-450SU1 and P-450SU2 from Streptomyces griseolus and choP from Streptomyces sp's cholesterol oxidase promoter region.
