scholarly journals Transposase-DNA Complex Structures Reveal Mechanisms for Conjugative Transposition of Antibiotic Resistance

Cell ◽  
2018 ◽  
Vol 173 (1) ◽  
pp. 208-220.e20 ◽  
Author(s):  
Anna Rubio-Cosials ◽  
Eike C. Schulz ◽  
Lotte Lambertsen ◽  
Georgy Smyshlyaev ◽  
Carlos Rojas-Cordova ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Complex Structures ◽  
Conjugative Transposition ◽  
Dna Complex

scholarly journals Quinolones: Mechanism, Lethality and Their Contributions to Antibiotic Resistance

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5662
Author(s):  
Natassja G. Bush ◽  
Isabel Diez-Santos ◽  
Lauren R. Abbott ◽  
Anthony Maxwell
Keyword(s):  
Cell Death ◽  
Antibiotic Resistance ◽  
Dna Gyrase ◽  
Mechanisms Of Action ◽  
Quinolone Resistance ◽  
Topoisomerase Iv ◽  
Bacterial Enzymes ◽  
Dna Topoisomerase ◽  
Quinolone Antibiotics ◽  
Dna Complex

Fluoroquinolones (FQs) are arguably among the most successful antibiotics of recent times. They have enjoyed over 30 years of clinical usage and become essential tools in the armoury of clinical treatments. FQs target the bacterial enzymes DNA gyrase and DNA topoisomerase IV, where they stabilise a covalent enzyme-DNA complex in which the DNA is cleaved in both strands. This leads to cell death and turns out to be a very effective way of killing bacteria. However, resistance to FQs is increasingly problematic, and alternative compounds are urgently needed. Here, we review the mechanisms of action of FQs and discuss the potential pathways leading to cell death. We also discuss quinolone resistance and how quinolone treatment can lead to resistance to non-quinolone antibiotics.

scholarly journals Structure of catabolite activator protein with cobalt(II) and sulfate

2014 ◽  
Vol 70 (5) ◽  
pp. 560-563 ◽  
Author(s):  
Ramya R. Rao ◽  
Catherine L. Lawson
Keyword(s):  
Transcription Activation ◽  
Complex Structures ◽  
Catabolite Activator Protein ◽  
Activator Protein ◽  
Terminal Domain ◽  
Dna Backbone ◽  
Cobalt Binding ◽  
Binding Residues ◽  
Dna Complex ◽  
Crystal Contact

The crystal structure of cyclic AMP–catabolite activator protein (CAP) fromEscherichia colicontaining cobalt(II) chloride and ammonium sulfate is reported at 1.97 Å resolution. Each of the two CAP subunits in the asymmetric unit binds one cobalt(II) ion, in each case coordinated by N-terminal domain residues His19, His21 and Glu96 plus an additional acidic residue contributedviaa crystal contact. The three identified N-terminal domain cobalt-binding residues are part of a region of CAP that is important for transcription activation at class II CAP-dependent promoters. Sulfate anions mediate additional crystal lattice contacts and occupy sites corresponding to DNA backbone phosphate positions in CAP–DNA complex structures.

Differential Effects of Phosphorylation on DNA Binding Properties of N Oct-3 Are Dictated by Protein/DNA Complex Structures

2007 ◽  
Vol 370 (4) ◽  
pp. 687-700 ◽  
Author(s):  
Laurence Nieto ◽  
Gérard Joseph ◽  
Alexandre Stella ◽  
Pauline Henri ◽  
Odile Burlet-Schiltz ◽  
...  
Keyword(s):  
Dna Binding ◽  
Complex Structures ◽  
Binding Properties ◽  
Differential Effects ◽  
Dna Complex ◽  
Dna Binding Properties

Quaternary-ammonium-bearing Aromatic Surfactants: Effect of the Alkyl Chain Positions on Their Micelle and DNA-complex Structures

2011 ◽  
Vol 40 (12) ◽  
pp. 1340-1342 ◽  
Author(s):  
Takuma Matsuo ◽  
Shota Fujii ◽  
Yumi Kamikawa ◽  
Tomoki Nishimura ◽  
Yusuke Sanada ◽  
...  
Keyword(s):  
Quaternary Ammonium ◽  
Alkyl Chain ◽  
Complex Structures ◽  
Dna Complex

scholarly journals Structural basis for topological regulation of Tn3 resolvase

2021 ◽  
Author(s):  
Sherwin P Montaño ◽  
Sally-J Rowland ◽  
James R. Fuller ◽  
Mary E. Burke ◽  
Alasdair I. MacDonald ◽  
...  
Keyword(s):  
Experimental Data ◽  
Antibiotic Resistance ◽  
Synthetic Biology ◽  
Enzymatic Activity ◽  
Dna Topology ◽  
Structural Basis ◽  
Detailed Model ◽  
Site Specific ◽  
Site Specific Recombination ◽  
Dna Complex

Site-specific DNA recombinases play a variety of biological roles, often related to the dissemination of antibiotic resistance, and are also useful synthetic biology tools. The simplest site-specific recombination systems will recombine any two cognate sites regardless of context. Other systems have evolved elaborate mechanisms, often sensing DNA topology, to ensure that only one of multiple possible recombination products is produced. The closely-related resolvases from the Tn3 and γδ transposons have historically served as paradigms for the regulation of recombinase activity by DNA topology. However, despite many proposals, models of the multi-subunit protein-DNA complex (termed the synaptosome) that enforces this regulation have been unsatisfying due to a lack of experimental constraints and incomplete concordance with experimental data. Here we present new structural and biochemical data that lead to a new, detailed model of the Tn3 synaptosome, and discuss how it harnesses DNA topology to regulate the enzymatic activity of the recombinase.

Cell morphology, volume, and surface area determinations from multilevel contouring within HVEM micrographs of serial sections and whole-cell mounts

1987 ◽  
Vol 45 ◽  
pp. 588-589
Author(s):  
M. Marko ◽  
A. Leith ◽  
D. Parsons
Keyword(s):  
Surface Area ◽  
Electron Micrographs ◽  
Cell Morphology ◽  
Individual Variation ◽  
Serial Section ◽  
Stereo Pair ◽  
Complex Structures ◽  
Serial Sections ◽  
Surface Areas ◽  
Computer Based

The use of serial sections and computer-based 3-D reconstruction techniques affords an opportunity not only to visualize the shape and distribution of the structures being studied, but also to determine their volumes and surface areas. Up until now, this has been done using serial ultrathin sections.The serial-section approach differs from the stereo logical methods of Weibel in that it is based on the Information from a set of single, complete cells (or organelles) rather than on a random 2-dimensional sampling of a population of cells. Because of this, it can more easily provide absolute values of volume and surface area, especially for highly-complex structures. It also allows study of individual variation among the cells, and study of structures which occur only infrequently.We have developed a system for 3-D reconstruction of objects from stereo-pair electron micrographs of thick specimens.

Stereo modeling of HVEM specimens by serial tilting and computer graphics

1986 ◽  
Vol 44 ◽  
pp. 34-35
Author(s):  
J.R. McIntosh ◽  
D.L. Stemple ◽  
William Bishop ◽  
G.W. Hannaway
Keyword(s):  
Computer Graphics ◽  
Analytical Methods ◽  
Photographic Film ◽  
Complex Structures ◽  
Multiple Objects ◽  
Multiple Images ◽  
3 Dimensional

EM specimens often contain 3-dimensional information that is lost during micrography on a single photographic film. Two images of one specimen at appropriate orientations give a stereo view, but complex structures composed of multiple objects of graded density that superimpose in each projection are often difficult to decipher in stereo. Several analytical methods for 3-D reconstruction from multiple images of a serially tilted specimen are available, but they are all time-consuming and computationally intense.

EXELFS Studies of Carbon Fibers

1990 ◽  
Vol 48 (2) ◽  
pp. 72-73
Author(s):  
V. Serin ◽  
K. Hssein ◽  
G. Zanchi ◽  
J. Sévely
Keyword(s):  
Carbon Fibers ◽  
Energy Analysis ◽  
Electron Excitation ◽  
Complex Structures ◽  
High Modulus ◽  
Promising Technique ◽  
X Ray ◽  
Fine Structures ◽  
X Ray Absorption

The present developments of electron energy analysis in the microscopes by E.E.L.S. allow an accurate recording of the spectra and of their different complex structures associated with the inner shell electron excitation by the incident electrons (1). Among these structures, the Extended Energy Loss Fine Structures (EXELFS) are of particular interest. They are equivalent to the well known EXAFS oscillations in X-ray absorption spectroscopy. Due to the EELS characteristic, the Fourier analysis of EXELFS oscillations appears as a promising technique for the characterization of composite materials, the major constituents of which are low Z elements. Using EXELFS, we have developed a microstructural study of carbon fibers. This analysis concerns the carbon K edge, which appears in the spectra at 285 eV. The purpose of the paper is to compare the local short range order, determined by this way in the case of Courtauld HTS and P100 ex-polyacrylonitrile carbon fibers, which are high tensile strength (HTS) and high modulus (HM) fibers respectively.

Silicification of wood-cell walls

1994 ◽  
Vol 52 ◽  
pp. 428-429
Author(s):  
S. E. Keckler ◽  
D. M. Dabbs ◽  
N. Yao ◽  
I. A. Aksay
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Cell Walls ◽  
Lignin Content ◽  
Resin Composite ◽  
Middle Lamella ◽  
Cellulose Fibers ◽  
Complex Structures ◽  
Rich Region ◽  
Inorganic Precursors

Cellular organic structures such as wood can be used as scaffolds for the synthesis of complex structures of organic/ceramic nanocomposites. The wood cell is a fiber-reinforced resin composite of cellulose fibers in a lignin matrix. A single cell wall, containing several layers of different fiber orientations and lignin content, is separated from its neighboring wall by the middle lamella, a lignin-rich region. In order to achieve total mineralization, deposition on and in the cell wall must be achieved. Geological fossilization of wood occurs as permineralization (filling the void spaces with mineral) and petrifaction (mineralizing the cell wall as the organic component decays) through infiltration of wood with inorganics after growth. Conversely, living plants can incorporate inorganics into their cells and in some cases into the cell walls during growth. In a recent study, we mimicked geological fossilization by infiltrating inorganic precursors into wood cells in order to enhance the properties of wood. In the current work, we use electron microscopy to examine the structure of silica formed in the cell walls after infiltration of tetraethoxysilane (TEOS).

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