Cross-sectional views of hemoglobin S fibers by electron microscopy and computer modeling.

Garrell, Robin L.; Crepeau, Richard H.; Edelstein, Stuart J.

doi:10.1073/pnas.76.3.1140

Cited by 12 publications

(6 citation statements)

References 8 publications

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“…Repeat lengths are known to vary for adhesion-prepared fibers (1,5,8), and both the adhesion and embedding methods used in these studies produced fibers with repeat distances that were within the previously observed range. The widths of the fibers were consistent with earlier measurements from adhesion-prepared fibers and with measured center-to-center spacings of fibers in cross sections of embedded bundles (11,13). The edges of adjacent fibers in the bundle are visible at the top and bottom of the lower image.…”

Section: Fiber Preparation and Image Analysissupporting

confidence: 76%

“…This embedding method has proven particularly successful when applied to bundles of HbS fibers produced by stirring concentrated solutions during polymerization (9). Cross-linking and stabilization of the fiber bundles was achieved by infiltration with-a glutaraldehyde/tannic acid mixture (10,11) and subsequent exposure to osmium tetroxide in solution. Thus stabilized, the specimens were dehydrated and embedded in an epoxytype resin.…”

Section: Fiber Preparation and Image Analysismentioning

confidence: 99%

See 1 more Smart Citation

Pairings and polarities of the 14 strands in sickle cell hemoglobin fibers.

Rodgers¹,

Crepeau²,

Edelstein³

1987

Proc. Natl. Acad. Sci. U.S.A.

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Sickle cell anemia results from the formation of hemoglobin S fibers in erythrocytes, and a greater understanding of the structure of these fibers should provide insights into the basis of the disease and aid in the development of effective antisickling agents. Improved reconstructions from electron micrographs of negatively stained single hemoglobin S fibers or embedded fiber bundles reveal that the 14 strands of the fiber are organized into pairs. The strands in each of the seven pairs are half-staggered, and from longitudinal views the polarity of each pair can be determined. The positions of the pairs and their polarities (three in one orientation; four in the opposite orientation) suggest a close relationship with the crystals ofdeoxyhemoglobin S composed of antiparallel pairs of half-staggered strands.The dramatic transformation of erythrocytes caused by the sickle mutation of hemoglobin is due to the association of the hemoglobin S (HbS) molecules into long fibers that align to distort the cell shape. Understanding the self-association of HbS molecules has been the goal of extensive research activity, with studies of the fiber structure by electron microscopy (1) and crystallographic investigations of HbS (2) both providing considerable information. The fiber structure is a complex helical assembly of 14 strands of HbS molecules with a core of 4 strands surrounded by 10 outer strands in a roughly hexagonal packing. The crystals of HbS appear to be related to the fibers, since the valine-,36 residue and other residues implicated in intermolecular contacts of the fibers lie at contacts in the crystals (see refs. 3 and 4). However, the exact relationship between the strands of the fibers and those present in the crystals has remained elusive. Defining this relationship would permit the detailed structural information available for the crystal to be applied to analysis of the complex molecular interactions in the fiber. A study of rare incomplete fibers has demonstrated that the absence of strands occurs in pairs (5), implying the existence of tightly associated double strands. The strands of each pair are staggered by half of a molecular diameter with respect to each other, and hence are possibly related to half-staggered strands also present in the crystal. In the absence of direct information on pairing and strand-pair polarity in the reconstructed images, however, it has not been possible to relate the crystal and fiber structures definitively. A tentative model was proposed that includes the introduction of the transformations necessary to convert linear to helical strands (4).While this model clarified certain aspects of the problem, particularly the role of a-chain mutations that influence fiber formation, additional information on strand pairing and polarity was needed. Such information would serve also to resolve questions raised by other laboratories concerning the possibility of 16-strand structures (6) or a 14-strand structure with other pairing arrangements (7). Improved images of negativ...

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Section: Fiber Preparation and Image Analysissupporting

confidence: 76%

Section: Fiber Preparation and Image Analysismentioning

confidence: 99%

Pairings and polarities of the 14 strands in sickle cell hemoglobin fibers.

Rodgers¹,

Crepeau²,

Edelstein³

1987

Proc. Natl. Acad. Sci. U.S.A.

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“…in the literature are complicated by differing criteria for estimating diameters (see discussion in Crepeau et al, 1 978b). Through use of a tannic acid embedding procedure it has also been possible to observe details in the cross-sectional images of embedded and sectioned fibers that are consistent with the cross-sectional projection predicted by the 14-fi1lament structural model (Garrell et al, 1979). Thus the weight of the available evidence is strongly in favor of the identity of the 14-filament quinary structure as the major fiber of interest in sickle cell disease.…”

Section: Sickle Cell Hemoglobinmentioning

confidence: 52%

Patterns in the quinary structures of proteins. Plasticity and inequivalence of individual molecules in helical arrays of sickle cell hemoglobin and tubulin

Edelstein¹

1980

Biophysical Journal

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The four recognized levels of organization of protein structure (primary through quaternary) are extended to add the designation quinary structure for the interactions within helical arrays, such as found for sickle cell hemoglobin fibers or tubulin units in microtubules. For sickle cell hemoglobin the main quinary structure is a 14-filament fiber, with a number of other minor forms also encountered. Degenerate forms of the 14-filament fibers can be characterized that lack specific pairs of filaments; evidence is presented which suggests an overall organization of the 14 filaments in pairs, with particular pairs aligned in an antiparallel orientation. For tubulin, a range of quinary structures can be detected depending on the number of protofilaments and whether adjacent protofilaments composed of alternating alpha- and beta-subunits are aligned with contacts between like or unlike subunits and with parallel or antiparallel polarity. Thus, in contrast to quarternary structure, which generally involves a fixed number of subunits, the quinary structures of proteins can exhibit marked plasticity and inequivalence in the juxtaposition of constituent molecules.

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“…A rather open and flexible helical structure, which seems to be based on two filaments winding around each other, is the sort of paired helical filament seen in Alz-heimer's disease (Wischik et al, 1985) and in aggregates of X protein from skeletal muscle (Bennett et al, 1985). Reconstructions have also been obtained of the complex helical filaments formed from sickle-cell hemoglobin (Carragher et al, 1988;Garrell et al, 1979). Electron microscopy and image processing have also given insights into aggregates of helical molecules such as actin in acrosomal processes (DeRosier et al, 19771, paramyosin in the core of some molluscan muscle thick filaments (Elliott and Bennett, 19841, crystalline tubes of myosin subfragment-2 (Quinlan and Stewart, 1987), and recA protein-DNA complexes (Egelman and Stasiak, 1986).…”

Section: Other Helical Objectsmentioning

confidence: 99%

Computer image processing of electron micrographs of biological structures with helical symmetry

Stewart

1988

J. Elec. Microsc. Tech.

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Methods are described for the analysis of electron micrographs of biological objects with helical symmetry and for the production of three-dimensional models of these structures using computer image reconstruction methods. Fourier-based processing of one- and two-dimensionally ordered planar arrays is described by way of introduction, before analysing the special properties of helices and their transforms. Conceiving helical objects as a sum of helical waves (analogous to the sum of planar waves used to describe a planar crystal) is shown to facilitate analysis and enable three-dimensional models to be produced, often from a single view of the object. The corresponding Fourier transform of such a sum of helical waves consists of a sum of Bessel function terms along layer lines. Special problems deriving from the overlapping along layer lines of terms of different Bessel order are discussed, and methods to separate these terms, based on analysing a number of different azimuthal views of the object by least squares, are described. Corrections to alleviate many technical and specimen-related problems are discussed in conjunction with a consideration of the computer methods used to actually process an image. A range of examples of helical objects, including viruses, microtubules, flagella, actin, and myosin filaments, are discussed to illustrate the range of problems that can be addressed by computer reconstruction methods.

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Cross-sectional views of hemoglobin S fibers by electron microscopy and computer modeling.

Cited by 12 publications

References 8 publications

Pairings and polarities of the 14 strands in sickle cell hemoglobin fibers.

Pairings and polarities of the 14 strands in sickle cell hemoglobin fibers.

Patterns in the quinary structures of proteins. Plasticity and inequivalence of individual molecules in helical arrays of sickle cell hemoglobin and tubulin

Computer image processing of electron micrographs of biological structures with helical symmetry

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