Cellular location and activity of Escherichia coli RecG proteins shed light on the function of its structurally unresolved C-terminus

RecG is a DNA translocase encoded by most species of bacteria. The Escherichia coli protein targets branched DNA substrates and drives the unwinding and rewinding of DNA strands. Its ability to remodel replication forks and to genetically interact with PriA protein have led to the idea that it plays an important role in securing faithful genome duplication. Here we report that RecG co-localises with sites of DNA replication and identify conserved arginine and tryptophan residues near its C-terminus that are needed for this localisation. We establish that the extreme C-terminus, which is not resolved in the crystal structure, is vital for DNA unwinding but not for DNA binding. Substituting an alanine for a highly conserved tyrosine near the very end results in a substantial reduction in the ability to unwind replication fork and Holliday junction structures but has no effect on substrate affinity. Deleting or substituting the terminal alanine causes an even greater reduction in unwinding activity, which is somewhat surprising as this residue is not uniformly present in closely related RecG proteins. More significantly, the extreme C-terminal mutations have little effect on localisation. Mutations that do prevent localisation result in only a slight reduction in the capacity for DNA repair. © 2014 The Author(s)

The RdgC protein employs a novel mechanism involving a finger domain to bind to circular DNA

The DNA-binding protein RdgC has been identified as an inhibitor of RecA-mediated homologous recombination in Escherichia coli. In Neisseria species, RdgC also has a role in virulence-associated antigenic variation. We have previously solved the crystal structure of the E. coli RdgC protein and shown it to form a toroidal dimer. In this study, we have conducted a mutational analysis of residues proposed to mediate interactions at the dimer interfaces. We demonstrate that destabilizing either interface has a serious effect on in vivo function, even though a stable complex with circular DNA was still observed. We conclude that tight binding is required for inhibition of RecA activity. We also investigated the role of the RdgC finger domain, and demonstrate that it plays a crucial role in the binding of circular DNA. Together, these data allow us to propose a model for how RdgC loads onto DNA. We discuss how RdgC might inhibit RecA-mediated strand exchange, and how RdgC might be displaced by other DNA metabolism enzymes such as polymerases and helicases

Current controlled driver for a Dielectric Barrier Discharge lamp

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Efficacy and safety of percutaneous microwave ablation and cementoplasty in the treatment of painful spinal metastases and myeloma

© 2018 American Society of Neuroradiology. All Rights Reserved. BACKGROUND AND PURPOSE: Painful spinal metastases are a common cause of cancer-related morbidity. Percutaneous ablation presents an attractive minimally invasive alternative to conventional therapies. We performed a retrospective review of 69 patients with 102 painful spinal metastases undergoing microwave ablation and cementoplasty to determine the efficacy and safety of this treatment. MATERIALS AND METHODS: Procedures were performed between January 2015 and October 2016 with the patient under general anesthesia using image guidance for 102 spinal metastases in 69 patients in the following areas: cervical (n 2), thoracic (n 50), lumbar (n 34), and sacral (n 16) spine. Tumor pathologies included the following: multiple myeloma (n 10), breast (n 27), lung (n 12), thyroid (n 6), prostate (n 5), colon (n 4), renal cell (n 3), oral squamous cell (n 1), and adenocarcinoma of unknown origin (n 1). Procedural efficacy was determined using the visual analog scale measured preprocedurally and at 2- 4 weeks and 20 -24 weeks postprocedure. Tumor locoregional control was assessed on follow-up cross-sectional imaging. Procedural complications were recorded to establish the safety profile. RESULTS: The median ablation time was 4 minutes 30 seconds 7 seconds, and energy dose, 4.1 1.6 kJ. Median visual analog scale scores were the following: 7.0 1.8 preprocedurally, 2 1.6 at 2- 4 weeks, and 2 2.1 at 20 -24 weeks. Eight patients died within 6 months following the procedure. Follow-up imaging in the surviving patients at 20 -24 weeks demonstrated no locoregional progression in 59/61 patients. Two complications were documented (S1 nerve thermal injury and skin burn). CONCLUSIONS: Microwave ablation is an effective and safe treatment technique for painful spinal metastases. Further studies may be helpful in determining the role of microwave ablation in locoregional control of metastases

Genetic data for D1S1677, D2S441, D4S2364, D10S1248, D14S1434 and D22S1045 miniSTR loci from Libya

2 p. : il.We determined the allelic frequencies for six miniSTR loci D1S1677, D2S441, D4S2364 (miniplex NC02) and D10S1248, D14S1434, D22S1045 (miniplex NC01) in a sample of 124 unrelated Libyans. Libya, a Northern African country, was first inhabited by Berbers, followed by Phoenicians, Greeks, Romans, Arabs and Ottomans. Libya became independent in 1951 after a brief period as Italian colony

Unique features of myogenesis in Egyptian cobra (Naja haje) (Squamata: Serpentes: Elapidae)

During early stages of myotomal myogenesis, the myotome of Egyptian cobra (Naja haje) is composed of homogenous populations of mononucleated primary myotubes. At later developmental phase, primary myotubes are accompanied by closely adhering mononucleated cells. Based on localization and morphology, we assume that mononucleated cells share features with satellite cells involved in muscle growth. An indirect morphological evidence of the fusion of mononucleated cells with myotubes is the presence of numerous vesicles in the subsarcolemmal region of myotubes adjacent to mononucleated cell. As differentiation proceeded, secondary muscle fibres appeared with considerably smaller diameter as compared to primary muscle fibre. Studies on N. haje myotomal myogenesis revealed some unique features of muscle differentiation. TEM analysis showed in the N. haje myotomes two classes of muscle fibres. The first class was characterized by typical for fast muscle fibres regular distribution of myofibrils which fill the whole volume of muscle fibre sarcoplasm. White muscle fibres in studied species were a prominent group of muscles in the myotome. The second class showed tightly paced myofibrils surrounding the centrally located nucleus accompanied by numerous vesicles of different diameter. The sarcoplasm of these cells was characterized by numerous lipid droplets. Based on morphological features, we believe that muscle capable of lipid storage belong to slow muscle fibres and the presence of lipid droplets in the sarcoplasm of these muscles during myogenesis might be a crucial adaptive mechanisms for subsequent hibernation in adults. This phenomenon was, for the first time, described in studies on N. haje myogenesis