Structure of a left-handed DNA G-quadruplex

Aside from the well-known double helix, DNA can also adopt an alternative four-stranded structure known as G-quadruplex. Implications of such a structure in cellular processes, as well as its therapeutic and diagnostic applications, have been reported. The G-quadruplex structure is highly polymorphic, but so far, only right-handed helical forms have been observed. Here we present the NMR solution and X-ray crystal structures of a left-handed DNA G-quadruplex. The structure displays unprecedented features that can be exploited as unique recognition elements.

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NMR solution and X-ray crystal structures of a DNA molecule containing both right- and left-handed parallel-stranded G-quadruplexes

Nucleic Acids Research ◽

10.1093/nar/gkz349 ◽

2019 ◽

Vol 47 (15) ◽

pp. 8272-8281 ◽

Cited By ~ 5

Author(s):

Fernaldo Richtia Winnerdy ◽

Blaž Bakalar ◽

Arijit Maity ◽

J Jeya Vandana ◽

Yves Mechulam ◽

...

Keyword(s):

Crystal Structures ◽

Double Helix ◽

Quadruple Helix ◽

Single Nucleotide ◽

Quadruplex Dna ◽

Dna Structures ◽

X Ray ◽

Left Handed ◽

G Quadruplex ◽

Quadruplex Formation

AbstractAnalogous to the B- and Z-DNA structures in double-helix DNA, there exist both right- and left-handed quadruple-helix (G-quadruplex) DNA. Numerous conformations of right-handed and a few left-handed G-quadruplexes were previously observed, yet they were always identified separately. Here, we present the NMR solution and X-ray crystal structures of a right- and left-handed hybrid G-quadruplex. The structure reveals a stacking interaction between two G-quadruplex blocks with different helical orientations and displays features of both right- and left-handed G-quadruplexes. An analysis of loop mutations suggests that single-nucleotide loops are preferred or even required for the left-handed G-quadruplex formation. The discovery of a right- and left-handed hybrid G-quadruplex further expands the polymorphism of G-quadruplexes and is potentially useful in designing a left-to-right junction in G-quadruplex engineering.

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Piecing together the ryanodine receptor with crystal structures and cryo-EM

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314085052 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C1494-C1494

Author(s):

Kelvin Lau ◽

Filip Van Petegem

Keyword(s):

Crystal Structures ◽

Ryanodine Receptor ◽

Calcium Ions ◽

Cardiac Tissue ◽

Loss Of Function ◽

Wild Type ◽

Calcium Signals ◽

X Ray ◽

Cellular Processes ◽

Wide Assortment

The ryanodine receptor is the largest ion channel known. It is responsible for the release of calcium ions from the intracellular stores of the sarcoplasmic/endoplasmic reticulum. The release of calcium signals for a wide assortment of cellular processes, most importantly, muscle contraction in skeletal and cardiac tissue. Only two regions of this receptor have been described by high-resolution crystal structures. In addition these two domains have been docked into low-resolution cryo-EM structures. Here, I will present a x-ray crystal structure of a novel domain from the ryanodine receptor of both skeletal and cardiac isoforms. Stability of the wild-type versus those of mutants will be discussed as well as the implications of the structure of a mutant linked to cardiac hypertrophy and a loss of function phenotype. The docked location of the domain within the whole channel may suggest its functional properties.

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Transmission electron microscope studies in special ceramics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108489 ◽

1978 ◽

Vol 36 (1) ◽

pp. 268-269

Author(s):

A. Zangvil ◽

L.J. Gauckler ◽

G. Schneider ◽

M. Rühle

Keyword(s):

Phase Diagrams ◽

Crystal Structures ◽

Thin Foil ◽

Limited Extent ◽

Complex Materials ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Electron Microscopes ◽

Lattice Resolution

The use of high temperature special ceramics which are usually complex materials based on oxides, nitrides, carbides and borides of silicon and aluminum, is critically dependent on their thermomechanical and other physical properties. The investigations of the phase diagrams, crystal structures and microstructural features are essential for better understanding of the macro-properties. Phase diagrams and crystal structures have been studied mainly by X-ray diffraction (XRD). Transmission electron microscopy (TEM) has contributed to this field to a very limited extent; it has been used more extensively in the study of microstructure, phase transformations and lattice defects. Often only TEM can give solutions to numerous problems in the above fields, since the various phases exist in extremely fine grains and subgrain structures; single crystals of appreciable size are often not available. Examples with some of our experimental results from two multicomponent systems are presented here. The standard ion thinning technique was used for the preparation of thin foil samples, which were then investigated with JEOL 200A and Siemens ELMISKOP 102 (for the lattice resolution work) electron microscopes.

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Crystal Structures of Fragments D and Double-D from Fibrinogen and Fibrin

Thrombosis and Haemostasis ◽

10.1055/s-0037-1615842 ◽

1999 ◽

Vol 82 (08) ◽

pp. 271-276 ◽

Cited By ~ 8

Author(s):

Glen Spraggon ◽

Stephen Everse ◽

Russell Doolittle

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Crystal Structures ◽

Structure And Function ◽

X Ray ◽

Long Period ◽

And Function

IntroductionAfter a long period of anticipation,1 the last two years have witnessed the first high-resolution x-ray structures of fragments from fibrinogen and fibrin.2-7 The results confirmed many aspects of fibrinogen structure and function that had previously been inferred from electron microscopy and biochemistry and revealed some unexpected features. Several matters have remained stubbornly unsettled, however, and much more work remains to be done. Here, we review several of the most significant findings that have accompanied the new x-ray structures and discuss some of the problems of the fibrinogen-fibrin conversion that remain unresolved. * Abbreviations: GPR—Gly-Pro-Arg-derivatives; GPRPam—Gly-Pro-Arg-Pro-amide; GHRPam—Gly-His-Arg-Pro-amide

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Synthesis of Sulfoquinovose and Sulfoquinovosyl Diacylglycerides, and a Fluorogenic Substrate for Sulfoquinovosidases

10.26434/chemrxiv.10566101.v1 ◽

2019 ◽

Author(s):

Yunyang Zhang ◽

Janice Mui ◽

Thimali Arumaperuma ◽

James P. Lingford ◽

ETHAN GODDARD-BORGER ◽

...

Keyword(s):

Crystal Structures ◽

Fluorogenic Substrate ◽

Potassium Salts ◽

X Ray ◽

Sulfoquinovosyl Diacylglycerol ◽

Sodium And Potassium

The sulfolipid sulfoquinovosyl diacylglycerol (SQDG) and its headgroup, the sulfosugar sulfoquinovose (SQ), are estimated to harbour up to half of all organosulfur in the biosphere. SQ is liberated from SQDG and related glycosides by the action of sulfoquinovosidases (SQases). We report a 10-step synthesis of SQDG that we apply to the preparation of saturated and unsaturated lipoforms. We also report an expeditious synthesis of SQ and (13C6)SQ, and X-ray crystal structures of sodium and potassium salts of SQ. Finally, we report the synthesis of a fluorogenic SQase substrate, methylumbelliferyl a-D-sulfoquinovoside, and examination of its cleavage kinetics by two recombinant SQases.

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