![]() ![]() For both types of gamma-ray bursts, "most of their energy comes in the form of pulses," or blips, Hakkila said. Supernovas, or star explosions, produce longer gamma-ray bursts as the dying stars collapse into black holes. ![]() ![]() When two neutron stars collide, they send out short gamma-ray bursts as they form a black hole. They produce more energy output than anything else that emits light, " said study lead author Jon Hakkila, an astrophysicist and associate dean of the Graduate School at the College of Charleston in South Carolina. 2011 77:7586–7594." Gamma-ray bursts are the most luminous sources known in nature. The RNA polymerase omega factor RpoZ is regulated by PhoP and has an important role in antibiotic biosynthesis and morphological differentiation in Streptomyces coelicolor. Santos-Beneit F, Barriuso-Iglesias M, Fernández-Martínez LT, Martínez-Castro M, Sola-Landa A, Rodríguez-García A, Martín JF. The rpoZ gene, encoding the RNA polymerase omega subunit, is required for antibiotic production and morphological differentiation in Streptomyces kasugaensis. Kojima I, Kasuga K, Kobayashi M, Fukasawa A, Mizuno S, Arisawa A, Akagawa H. rpoZ, encoding the omega subunit of Escherichia coli RNA polymerase, is in the same operon as spoT. Escherichia coli RNA polymerase subunit ω and its N-terminal domain bind full-length β' to facilitate incorporation into the α2β subassembly. Crystal structure of a bacterial RNA polymerase holoenzyme at 2.6 Å resolution. Vassylyev DG, Sekine S, Laptenko O, Lee J, Vassylyeva MN, Borukhov S, Yokoyama S. The predicted PCR product sizes are 130 bp (P3 + P4), 78 bp (P5 + P6) and 795 bp (P5 + P4). The –RT1 and –RT2 denotes control reactions for primers P3 and P5, respectively, where no reverse transcriptase was added. ( D) RNA was isolated from CS, and reverse transcription was performed using the primer P3 or P5, and then complementary DNA was amplified by PCR. Expected fragment sizes are 5 bp for the control and ΔrpoZ strains, respectively. Genomic DNA was isolated from the control (CS) and ΔrpoZ strains, and the rpoZ gene was amplified. Primers P3, P4, P5 and P6 were used in the reverse transcription and subsequent PCR analysis. Primers P1 and P2 were used for construction and PCR verification of the mutant strain, the kanamycin cassette (Kn) was inserted in the middle of the rpoZ gene in antisense orientation. The rpoZ gene region of the genome and construction of the ΔrpoZ strain ( A) A schematic drawing of the rpoZ region of the genome and a ΔrpoZ strain. The results indicate that the ω subunit facilitates the association of the primary σ factor with the RNAP core, thereby allowing efficient transcription of highly expressed genes. Especially, genes encoding proteins of photosynthetic carbon concentrating and carbon fixing complexes were down, and the ΔrpoZ mutant showed low light-saturated photosynthetic activity and accumulated photoprotective carotenoids and α-tocopherol. In ΔrpoZ strain, recruitment of the primary σ factor into the RNAP holoenzyme is inefficient, which causes downregulation of highly expressed genes and upregulation of many low-expression genes. We found that although ω is non-essential in cyanobacteria, it has a major impact on the overall gene expression pattern. The physiological roles of the small ω subunit of RNAP, encoded by the rpoZ gene, are not yet completely understood in any bacteria. Cyanobacteria, a group of eubacteria characterized by oxygenic photosynthesis, have a unique composition of the RNA polymerase (RNAP) core due to splitting of the β' subunit to N-terminal γ and C-terminal β' subunits. An additional σ subunit is recruited for promoter recognition and transcription initiation. The eubacterial RNA polymerase core, a transcription machinery performing DNA-dependent RNA polymerization, consists of two α subunits and β, β' and ω subunits. ![]()
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