Structure and Assembly of the Spliceosomal snRNPs

2001 ◽  
Vol 29 (2) ◽  
pp. 15-26 ◽  
Author(s):  
K. Nagai ◽  
Y. Muto ◽  
D. A. Pomeranz Krummel ◽  
C. Kambach ◽  
T. Ignjatovic ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Protein Complexes ◽  
Mrna Splicing ◽  
Protein Recognition ◽  
Conserved Sequences ◽  
X Ray ◽  
Rna Protein Complexes ◽  
Insight Into

The spliceosome is a macromolecular machine that carries out the excision of introns from eukaryotic pre-mRNAs and splicing together of exons. Four large RNA-protein complexes, called the U1, U2, U4/U6 and U5 small nuclear ribo-nucleoprotein particles (snRNPs), and some non-snRNP proteins assemble around three short conserved sequences within the intron in an ordered manner to form the active spliceosome. We aim to provide insight into the molecular details of the mechanism of pre-mRNA splicing through crystallographic studies of the snRNPs. We have solved the X-ray crystal structure of some snRNP proteins as part of either protein-protein complexes or RNA-protein complexes. These structures have provided an important insight into the overall architecture of the U1 and U2 snRNPs and the mechanisms of RNA-protein and protein-protein recognition.

scholarly journals Discovery of Fe7O9: a new iron oxide with a complex monoclinic structure

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Ryosuke Sinmyo ◽  
Elena Bykova ◽  
Sergey V. Ovsyannikov ◽  
Catherine McCammon ◽  
Ilya Kupenko ◽  
...  
Keyword(s):  
Applied Sciences ◽  
Crystal Structure ◽  
Iron Oxide ◽  
Iron Oxides ◽  
Industrial Applications ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Insight Into

Abstract Iron oxides are fundamentally important compounds for basic and applied sciences as well as in numerous industrial applications. In this work we report the synthesis and investigation of a new binary iron oxide with the hitherto unknown stoichiometry of Fe7O9. This new oxide was synthesized at high-pressure high-temperature (HP-HT) conditions, and its black single crystals were successfully recovered at ambient conditions. By means of single crystal X-ray diffraction we determined that Fe7O9 adopts a monoclinic C2/m lattice with the most distorted crystal structure among the binary iron oxides known to date. The synthesis of Fe7O9 opens a new portal to exotic iron-rich (M,Fe)7O9 oxides with unusual stoichiometry and distorted crystal structures. Moreover, the crystal structure and phase relations of such new iron oxide groups may provide new insight into the cycling of volatiles in the Earth’s interior.

Influence of crystal structure, ligand environment and morphology on CoL-edge XAS spectral characteristics in cobalt compounds

2015 ◽  
Vol 22 (6) ◽  
pp. 1450-1458 ◽  
Author(s):  
D. K. Bora ◽  
X. Cheng ◽  
M. Kapilashrami ◽  
P. A. Glans ◽  
Y. Luo ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electronic Structure ◽  
Metal Ion ◽  
Spectral Characteristics ◽  
Branching Ratio ◽  
Central Metal ◽  
X Ray ◽  
Cobalt Compounds ◽  
X Ray Absorption ◽  
Insight Into

The electronic structure of a material plays an important role in its functionality for different applications which can be probed using synchrotron-based spectroscopy techniques. Here, various cobalt-based compounds, differing in crystal structure, ligands surrounding the central metal ion and morphology, have been studied by soft X-ray absorption spectroscopy (XAS) at the CoL-edge in order to measure the effect of these parameters on the electronic structure. A careful qualitative analysis of the spectral branching ratio and relative intensities of theL3andL2peaks provide useful insight into the electronic properties of compounds such as CoO/Co(OH)2, CoCl2.6H2O/CoF2.4H2O, CoCl2/CoF2, Co3O4(bulk/nano/micro). For further detailed analysis of the XAS spectra, quantitative analysis has been performed by fitting the spectral profile with simulated spectra for a number of cobalt compounds using crystal field atomic multiplet calculations.

scholarly journals Azobenzene-based difunctional halogen-bond donor: towards the engineering of photoresponsive co-crystals

2013 ◽  
Vol 70 (1) ◽  
pp. 149-156 ◽  
Author(s):  
Marco Saccone ◽  
Giancarlo Terraneo ◽  
Tullio Pilati ◽  
Gabriella Cavallo ◽  
Arri Priimagi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Halogen Bond ◽  
Halogen Bonding ◽  
X Ray Diffraction ◽  
Donor Molecule ◽  
X Ray ◽  
Covalent Interaction ◽  
Material Systems ◽  
Azo Group ◽  
Insight Into

Halogen bonding is emerging as a powerful non-covalent interaction in the context of supramolecular photoresponsive materials design, particularly due to its high directionality. In order to obtain further insight into the solid-state features of halogen-bonded photoactive molecules, three halogen-bonded co-crystals containing an azobenzene-based difunctional halogen-bond donor molecule, (E)-bis(4-iodo-2,3,5,6-tetrafluorophenyl)diazene, C12F8I2N2, have been synthesized and structurally characterized by single-crystal X-ray diffraction. The crystal structure of the non-iodinated homologue (E)-bis(2,3,5,6-tetrafluorophenyl)diazene, C12H2F8N2, is also reported. It is demonstrated that the studied halogen-bond donor molecule is a reliable tecton for assembling halogen-bonded co-crystals with potential photoresponsive behaviour. The azo group is not involved in any specific intermolecular interactions in any of the co-crystals studied, which is an interesting feature in the context of enhanced photoisomerization behaviour and photoactive properties of the material systems.

scholarly journals Functional organization of box C/D RNA-guided RNA methyltransferase

2020 ◽  
Vol 48 (9) ◽  
pp. 5094-5105
Author(s):  
Zuxiao Yang ◽  
Jiayin Wang ◽  
Lin Huang ◽  
David M J Lilley ◽  
Keqiong Ye
Keyword(s):  
Recombinant Proteins ◽  
Mechanism Of Action ◽  
Functional Organization ◽  
Protein Complexes ◽  
Site Specific ◽  
Guide Rnas ◽  
Chaetomium Thermophilum ◽  
Rna Protein Complexes ◽  
Insight Into

Abstract Box C/D RNA protein complexes (RNPs) catalyze site-specific 2′-O-methylation of RNA with specificity determined by guide RNAs. In eukaryotic C/D RNP, the paralogous Nop58 and Nop56 proteins specifically associate with terminal C/D and internal C'/D' motifs of guide RNAs, respectively. We have reconstituted active C/D RNPs with recombinant proteins of the thermophilic yeast Chaetomium thermophilum. Nop58 and Nop56 could not distinguish between the two C/D motifs in the reconstituted enzyme, suggesting that the assembly specificity is imposed by trans-acting factors in vivo. The two C/D motifs are functionally independent and halfmer C/D RNAs can also guide site-specific methylation. Extensive pairing between C/D RNA and substrate is inhibitory to modification for both yeast and archaeal C/D RNPs. N6-methylated adenine at box D/D' interferes with the function of the coupled guide. Our data show that all C/D RNPs share the same functional organization and mechanism of action and provide insight into the assembly specificity of eukaryotic C/D RNPs.

scholarly journals Understanding the Solid-State Assembly of Pharmaceutically-Relevant N,N-Dimethyl-O-Thiocarbamates in the Absence of Labile Hydrogen Bonds

2020 ◽  
Author(s):  
Davin Tan ◽  
Zi xuan Ng ◽  
Rakesh Ganguly ◽  
yongxin Li ◽  
Han Sen Soo ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Molecular Geometry ◽  
Pharmaceutical Compounds ◽  
Labile Hydrogen ◽  
X Ray Diffraction ◽  
Hydrogen Bond Donor ◽  
X Ray ◽  
Medicinal Properties ◽  
Insight Into

There are many pharmaceutical compounds that do not contain N-H, O-H, and S-H hydrogen-bond donor functional groups. Some of these compounds are N,N-disubstituted O-thiocarbamates which exhibit desirable medicinal properties, yet the study of these important molecules in the solid-state has been relatively unexplored. Herein, we report the synthesis and analysis of a series of N,N-dimethyl-O-thiocarbamates, and use X-ray diffraction techniques to gain insight into how these molecules self-assemble in the solid-state and discern certain packing patterns. It was observed that the aryl-thiocarbamate C-O bonds are twisted such that the planar aryl and carbamate moieties are orthogonal. Such a non-planar molecular geometry affects the way the molecules pack and crystal structure analyses revealed four general modes in which the molecules can associate in the solid-state, with some members of the series displaying isostructural relationships. The crystal structure of a well-known yet unreported O-thiocarbamate drug, Tolnaftate, is also reported. Additionally, Hirshfeld surface analysis was also performed on these compounds as well as several related O-thiocarbamates in the literature.<br>

scholarly journals Understanding the Solid-State Assembly of Pharmaceutically-Relevant N,N-Dimethyl-O-Thiocarbamates in the Absence of Labile Hydrogen Bonds

2020 ◽  
Author(s):  
Davin Tan ◽  
Zi xuan Ng ◽  
Rakesh Ganguly ◽  
yongxin Li ◽  
Han Sen Soo ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Molecular Geometry ◽  
Pharmaceutical Compounds ◽  
Labile Hydrogen ◽  
X Ray Diffraction ◽  
Hydrogen Bond Donor ◽  
X Ray ◽  
Medicinal Properties ◽  
Insight Into

There are many pharmaceutical compounds that do not contain N-H, O-H, and S-H hydrogen-bond donor functional groups. Some of these compounds are N,N-disubstituted O-thiocarbamates which exhibit desirable medicinal properties, yet the study of these important molecules in the solid-state has been relatively unexplored. Herein, we report the synthesis and analysis of a series of N,N-dimethyl-O-thiocarbamates, and use X-ray diffraction techniques to gain insight into how these molecules self-assemble in the solid-state and discern certain packing patterns. It was observed that the aryl-thiocarbamate C-O bonds are twisted such that the planar aryl and carbamate moieties are orthogonal. Such a non-planar molecular geometry affects the way the molecules pack and crystal structure analyses revealed four general modes in which the molecules can associate in the solid-state, with some members of the series displaying isostructural relationships. The crystal structure of a well-known yet unreported O-thiocarbamate drug, Tolnaftate, is also reported. Additionally, Hirshfeld surface analysis was also performed on these compounds as well as several related O-thiocarbamates in the literature.<br>

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