scholarly journals Three-dimensional reconstruction of a simple Z-band in fish muscle.

1991 ◽  
Vol 113 (5) ◽  
pp. 1043-1055 ◽  
Author(s):  
P K Luther
Keyword(s):  
Actin Filament ◽  
Actin Filaments ◽  
Rotational Symmetry ◽  
Three Dimensional ◽  
The Other ◽  
Dimensional Structure ◽  
Central Plane ◽  
Three Dimensional Structure ◽  
Proximal Site ◽  
Distal Site

The three-dimensional structure of the Z-band in fish white muscle has been investigated by electron microscopy. This Z-band is described as simple, since in longitudinal sections it has the appearance of a single zigzag pattern connecting the ends of actin filaments of opposite polarity from adjacent sarcomeres. The reconstruction shows two pairs of links, the Z-links, between one actin filament and the facing four actin filaments in the adjacent sarcomere. The members of each pair have nearly diametrically opposed origins. In relation to one actin filament, one pair of links appears to bind along the final 10 nm of the actin filament (proximal site) and the other pair binds along a region extending from 5 to 20 nm from the filament end (distal site). Between one pair and the other, there is a rotation of approximately 80 degrees round the filament axis. A Z-link with a proximal site at the end of one actin filament attaches at a distal site on the oppositely oriented actin filaments of the facing sarcomere and vice versa. The length of each Z-link is consistent with the length of an alpha-actinin molecule. An additional set of links located 10-15 nm from the center of the Z-band occurs between actin filaments of the same polarity. These polar links connect the actin filaments along the same direction on each side of the Z-band. The three-dimensional structure appears to have twofold screw symmetry about the central plane of the Z-band. Only approximate twofold rotational symmetry is observed in directions parallel to the actin filaments. Previous models of the Z-band in which four identical and rotationally symmetrical links emanate from the end of one actin filament and span across to the ends of four actin filaments in the adjacent sarcomere are therefore incorrect.

scholarly journals Arrangement of filaments and cross-links in the bee flight muscle Z disk by image analysis of oblique sections.

1989 ◽  
Vol 108 (5) ◽  
pp. 1775-1782 ◽  
Author(s):  
J F Deatherage ◽  
N Q Cheng ◽  
B Bullard
Keyword(s):  
Actin Filaments ◽  
Flight Muscle ◽  
Three Dimensional ◽  
Thick Filament ◽  
Opposite Polarity ◽  
Dimensional Structure ◽  
Central Plane ◽  
Thin Sections ◽  
Three Dimensional Structure ◽  
Rotation Axes

Information from oblique thin sections and from three-dimensional reconstructions of tilted, transverse thin sections (Cheng, N., and J. F. Deatherage. 1989. J. Cell Biol. 108:1761-1774) has been combined to determine the three-dimensional structure of the honeybee flight muscle Z disk at 70-A resolution. The overall symmetry and structure of the Z disk and its relationship to the rest of the myofibril have been determined by tracing filaments and connecting elements on electron images of oblique sections which have been enhanced by a local crystallographic averaging technique. In the three-dimensional structure, the connecting density between actin filaments can be described as five compact, crystallographically nonequivalent domains. Features C1 and C2 are located on the transverse twofold rotation axes in the central plane of the Z disk. They are associated with the sides of actin filaments of opposite polarity. Features C3, C4, and C5 are present in two symmetry-related sets which are located on opposite sides of the central plane. C3 and C5 are each associated with two filaments of opposite polarity, interacting with the side of one filament and the end of the other filament. C3 and C5 may be involved in stabilizing actin filament ends inside the Z disk. The location of the threefold symmetric connection C4, relative to the thick filament of the adjacent sarcomere, is determined and its possible relationship to the C filament is considered.

scholarly journals Bis(μ2-4-nitrophenolato)bis(4-nitrophenolato)di-μ3-oxido-octaphenyltetratin chloroform sesquisolvate [+ solvate]: a tetranuclear stannoxane

IUCrData ◽  
2019 ◽  
Vol 4 (8) ◽  
Author(s):  
Patrick Butler
Keyword(s):  
Hydrogen Bonds ◽  
Electron Density ◽  
Three Dimensional ◽  
The Other ◽  
Dimensional Structure ◽  
Coordination Geometry ◽  
Asymmetric Unit ◽  
Acta Cryst ◽  
Complex Molecules ◽  
Three Dimensional Structure

The title tetranuclear stannoxane, [Sn4(C6H5)8(C6H4NO3)4O2]·1.5CHCl3·solvent, crystallized with two independent complex molecules, A and B, in the asymmetric unit together with 1.5 molecules of chloroform. There is also a region of disordered electron density, which was corrected for using the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9–18]. The oxo-tin core of each complex is in a planar `ladder' arrangement and each Sn atom is fivefold SnO3C2 coordinated, with one tin centre having an almost perfect square-pyramidal coordination geometry, while the other three Sn centres have distorted shapes. In the crystal, the complex molecules are arranged in layers, composed of A or B complexes, lying parallel to the bc plane. The complex molecules are linked by a number of C—H...O hydrogen bonds within the layers and between the layers, forming a supramolecular three-dimensional structure.

scholarly journals Three-dimensional structure of actin filaments and of an actin gel made with actin-binding protein.

1983 ◽  
Vol 96 (5) ◽  
pp. 1400-1413 ◽  
Author(s):  
R Niederman ◽  
P C Amrein ◽  
J Hartwig
Keyword(s):  
Actin Filaments ◽  
Binding Protein ◽  
Three Dimensional ◽  
Actin Binding ◽  
Dimensional Structure ◽  
Molar Ratio ◽  
Computer Assisted ◽  
Three Dimensional Structure ◽  
Actin Binding Protein ◽  
Critical Point Drying

Purified muscle actin and mixtures of actin and actin-binding protein were examined in the transmission electron microscope after fixation, critical point drying, and rotary shadowing. The three-dimensional structure of the protein assemblies was analyzed by a computer-assisted graphic analysis applicable to generalized filament networks. This analysis yielded information concerning the frequency of filament intersections, the filament length between these intersections, the angle at which filaments branch at these intersections, and the concentration of filaments within a defined volume. Purified actin at a concentration of 1 mg/ml assembled into a uniform mass of long filaments which overlap at random angles between 0 degrees and 90 degrees. Actin in the presence of macrophage actin-binding protein assembled into short, straight filaments, organized in a perpendicular branching network. The distance between branch points was inversely related to the molar ratio of actin-binding protein to actin. This distance was what would be predicted if actin filaments grew at right angles off of nucleation sites on the two ends of actin-binding protein dimers, and then annealed. The results suggest that actin in combination with actin-binding protein self-assembles to form a three-dimensional network resembling the peripheral cytoskeleton of motile cells.

scholarly journals Three-dimensional structure of a single filament in the Limulus acrosomal bundle: scruin binds to homologous helix-loop-beta motifs in actin

1994 ◽  
Vol 124 (3) ◽  
pp. 341-350 ◽  
Author(s):  
MF Schmid ◽  
JM Agris ◽  
J Jakana ◽  
P Matsudaira ◽  
W Chiu
Keyword(s):  
Actin Filament ◽  
Three Dimensional ◽  
Computational Procedure ◽  
Unit Cell ◽  
Dimensional Structure ◽  
Single Filament ◽  
Three Dimensional Structure ◽  
Helical Reconstruction

Frozen, hydrated acrosomal bundles from Limulus sperm were imaged with a 400 kV electron cryomicroscope. Segments of this long bundle can be studied as a P1 crystal with a unit cell containing an acrosomal filament with 28 actin and 28 scruin molecules in 13 helical turns. A novel computational procedure was developed to extract single columns of superimposed acrosomal filaments from the distinctive crystallographic view. Helical reconstruction was used to generate a three-dimensional structure of this computationally isolated acrosomal filament. The scruin molecule is organized into two domains which contact two actin subunits in different strands of the same actin filament. A correlation of Holmes' actin filament model to the density in our acrosomal filament map shows that actin subdomains 1, 2, and 3 match the model density closely. However, actin subdomain 4 matches rather poorly, suggesting that interactions with scruin may have altered actin conformation. Scruin makes extensive interactions with helix-loop-beta motifs in subdomain 3 of one actin subunit and in subdomain 1 of a consecutive actin subunit along the genetic filament helix. These two actin subdomains are structurally homologous and are closely spaced along the actin filament. Our model suggests that scruin, which is derived from a tandemly duplicated gene, has evolved to bind structurally homologous but non-identical positions across two consecutive actin subunits.

scholarly journals Three-Dimensional Structure of Vinculin Bound to Actin Filaments

2006 ◽  
Vol 21 (2) ◽  
pp. 271-281 ◽  
Author(s):  
Mandy E.W. Janssen ◽  
Eldar Kim ◽  
Hongjun Liu ◽  
L. Miya Fujimoto ◽  
Andrey Bobkov ◽  
...  
Keyword(s):  
Actin Filaments ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Three Dimensional Structure

scholarly journals Three-Dimensional Structure of the Neisseria meningitidis Secretin PilQ Determined from Negative-Stain Transmission Electron Microscopy

2003 ◽  
Vol 185 (8) ◽  
pp. 2611-2617 ◽  
Author(s):  
Richard F. Collins ◽  
Robert C. Ford ◽  
Ashraf Kitmitto ◽  
Ranveig O. Olsen ◽  
Tone Tønjum ◽  
...  
Keyword(s):  
Neisseria Meningitidis ◽  
Outer Membrane ◽  
Protein Complex ◽  
Rotational Symmetry ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Three Dimensional Structure ◽  
Type Iv ◽  
Negative Stain ◽  
Dominant Feature

ABSTRACT The PilQ secretin from the pathogenic bacterium Neisseria meningitidis is an integral outer membrane protein complex which plays a crucial role in the biogenesis of type IV pili. We present here the first three-dimensional structure of this type of secretin at 2.5-nm resolution, obtained by single-particle averaging methods applied to the purified protein complex visualized in a negative stain. In projection, the PilQ complex is circular, with a donut-like appearance. When viewed from the side it has a rounded, conical profile. The complex was demonstrated to have 12-fold rotational symmetry, and this property was used to improve the quality of the density map by symmetry averaging. The dominant feature of the structure is a cavity, 10 nm deep, within the center of the molecule. The cavity is funnel-shaped in cross section, measures 6.5 nm in diameter at the top of the complex, and tapers to a closed point, effectively blocking formation of a continuous pore through the PilQ complex. These results suggest that the complex would have to undergo a conformational change in order to accommodate an assembled pilus fiber of diameter 6.5 nm running through the outer membrane.

scholarly journals Three-dimensional Structure of Acanthamoeba castellanii Myosin-IB (MIB) Determined by Cryoelectron Microscopy of Decorated Actin Filaments

1998 ◽  
Vol 141 (1) ◽  
pp. 155-162 ◽  
Author(s):  
James D. Jontes ◽  
E. Michael Ostap ◽  
Thomas D. Pollard ◽  
Ronald A. Milligan
Keyword(s):  
Actin Filaments ◽  
Catalytic Domain ◽  
Three Dimensional ◽  
Acanthamoeba Castellanii ◽  
Dimensional Structure ◽  
Cryoelectron Microscopy ◽  
Tail Domain ◽  
Three Dimensional Structure ◽  
Myosin I ◽  
Carboxy Terminal

The Acanthamoeba castellanii myosin-Is were the first unconventional myosins to be discovered, and the myosin-I class has since been found to be one of the more diverse and abundant classes of the myosin superfamily. We used two-dimensional (2D) crystallization on phospholipid monolayers and negative stain electron microscopy to calculate a projection map of a “classical” myosin-I, Acanthamoeba myosin-IB (MIB), at ∼18 Å resolution. Interpretation of the projection map suggests that the MIB molecules sit upright on the membrane. We also used cryoelectron microscopy and helical image analysis to determine the three-dimensional structure of actin filaments decorated with unphosphorylated (inactive) MIB. The catalytic domain is similar to that of other myosins, whereas the large carboxy-terminal tail domain differs greatly from brush border myosin-I (BBM-I), another member of the myosin-I class. These differences may be relevant to the distinct cellular functions of these two types of myosin-I. The catalytic domain of MIB also attaches to F-actin at a significantly different angle, ∼10°, than BBM-I. Finally, there is evidence that the tails of adjacent MIB molecules interact in both the 2D crystal and in the decorated actin filaments.

scholarly journals Structure-function relationships in the cysteine proteinases actinidin, papain and papaya proteinase Ω. Three-dimensional structure of papaya proteinase Ω deduced by knowledge-based modelling and active-centre characteristics determined by two-hydronic-state reactivity probe kinetics and kinetics of catalysis

1991 ◽  
Vol 280 (1) ◽  
pp. 79-92 ◽  
Author(s):  
C M Topham ◽  
E Salih ◽  
C Frazao ◽  
D Kowlessur ◽  
J P Overington ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Catalytic Site ◽  
The Other ◽  
Dimensional Structure ◽  
Cysteine Proteinases ◽  
Three Dimensional Structure ◽  
Knowledge Based ◽  
Thiol Reactivity ◽  
Ph Dependent ◽  
Kinetics Of

1. A model of the three-dimensional structure of papaya proteinase omega, the most basic cysteine proteinase component of the latex of papaya (Carica papaya), was built from its amino acid sequence and the two currently known high-resolution crystal structures of the homologous enzymes papain (EC 3.4.22.2) and actinidin (EC 3.4.22.14). The method used a knowledge-based approach incorporated in the COMPOSER suite of programs and refinement by using the interactive graphics program FRODO on an Evans and Sutherland PS 390 and by energy minimization using the GROMOS program library. 2. Functional similarities and differences between the three cysteine proteinases revealed by analysis of pH-dependent kinetics of the acylation process of the catalytic act and of the reactions of the enzyme catalytic sites with substrate-derived 2-pyridyl disulphides as two-hydronic-state reactivity probes are reported and discussed in terms of the knowledge-based model. 3. To facilitate analysis of complex pH-dependent kinetic data, a multitasking application program (SKETCHER) for parameter estimation by interactive manipulation of calculated curves and a simple method of writing down pH-dependent kinetic equations for reactions involving any number of reactive hydronic states by using information matrices were developed. 4. Papaya proteinase omega differs from the other two enzymes in the ionization characteristics of the common (Cys)-SH/(His)-Im+H catalytic-site system and of the other acid/base groups that modulate thiol reactivity towards substrate-derived inhibitors and the acylation process of the catalytic act. The most marked difference in the Cys/His system is that the pKa for the loss of the ion-pair state to form -S-/-Im is 8.1-8.3 for papaya proteinase omega, whereas it is 9.5 for both actinidin and papain. Papaya proteinase omega is similar to actinidin in that it lacks the second catalytically influential group with pKa approx. 4 present in papain and possesses a catalytically influential group with pKa 5.5-6.0. 5. Papaya proteinase omega occupies an intermediate position between actinidin and papain in the sensitivity with which hydrophobic interaction in the S2 subsite is transmitted to produce changes in transition-state geometry in the catalytic site, a fact that may be linked with differences in specificity in P2-S2 interaction exhibited by the three enzymes.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Synthesis and crystallographic characterization of a mononuclear cobalt(III) complex possessing both thiolate and thioether donors: reactivity of an thiolate-bridged pentanuclear Co2Ag3complex with iodomethane

2017 ◽  
Vol 73 (5) ◽  
pp. 678-681
Author(s):  
Yosuke Fukuda ◽  
Nobuto Yoshinari ◽  
Takumi Konno
Keyword(s):  
Hydrogen Bonds ◽  
Title Compound ◽  
Three Dimensional ◽  
Mononuclear Complex ◽  
The Other ◽  
Dimensional Structure ◽  
Cationic Complex ◽  
Three Dimensional Structure ◽  
Mononuclear Cobalt

Treatment of an S-bridged pentanuclear AgI3CoIII2complex, [Ag3{Co(L)}2]3+[L3–= N(CH2NHCH2CH2S−)3], in which two tris(thiolate)-type mononuclear CoIIIunits ([Co(L)]) are bridged by three AgIions through S atoms, with iodomethane (CH3I) gave a new CoIIImononuclear complex, [Co(LMe2)]2+[LMe2−= N(CH2NHCH2CH2S−)(CH2NHCH2CH2SCH3)2], systematic name: {2-[(bis{[2-(methylsulfanyl)ethyl]aminomethyl}aminomethyl)amino]ethanethiolato}cobalt(III) bis(hexafluoridophosphate). This cationic complex was crystallized with PF6−anions to form the title compound, [Co(LMe2)](PF6)2. In the [Co(LMe2)]2+cation, two of three thiolate groups in [Co(L)] are methylated while one thiolate group remains unreacted. Although a total of eight stereoisomers are possible for [Co(LMe2)]2+, only a pair of enantiomers {ΛRR- and ΔSS-[Co(LMe2)]2+} are selectively formed. In the crystal, the complex cations and the PF6−anions are connected through weak N—H...F, C—H...F and C—H...S hydrogen bonds into a three-dimensional structure. Two F atoms in one PF6anion are disordered over two sets of sites with refined occupancies of 0.61 (4) and 0.39 (4) and two F atoms in the other PF6−anion are disordered over two sets of sites with occupancies of 0.5.

scholarly journals Structural Study of the Serratia entomophila Antifeeding Prophage: Three-Dimensional Structure of the Helical Sheath

2010 ◽  
Vol 192 (17) ◽  
pp. 4522-4525 ◽  
Author(s):  
Anindito Sen ◽  
Daria Rybakova ◽  
Mark R. H. Hurst ◽  
Alok K. Mitra
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
New Zealand ◽  
Structural Study ◽  
Three Dimensional ◽  
The Other ◽  
Dimensional Structure ◽  
Three Dimensional Structure ◽  
Costelytra Zealandica

ABSTRACT The sheath of the Serratia entomophila antifeeding prophage, which is pathogenic to the New Zealand grass grub Costelytra zealandica, is a 3-fold helix formed by a 4-fold symmetric repeating motif disposed around a helical inner tube. This structure, determined by electron microscopy and image processing, is distinct from that of the other known morphologically similar bacteriophage sheaths.

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