The packing of α-helices: simple coiled-coils
10 Sep 1953-Acta Crystallographica (International Union of Crystallography)-Vol. 6, Iss: 8, pp 689-697
TL;DR: In this paper, the two-strand rope and three-stranded rope models were described and used to illustrate the diffraction theory already developed, and it was shown that they would give a diffuse pattern.
Abstract: It is shown in this paper by Crick that when -helices of the same sense pack together they will probably do so about 20° away from parallel. For very long chains this may lead to a coiled-coil. The two simplest models - the two-strand rope and the three-strand rope - are described, and used to illustrate the diffraction theory already developed. It is shown that they would give a diffuse -pattern. Possible examples of these models are briefly discussed.
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TL;DR: This chapter investigates the anatomy and taxonomy of protein structures, based on the results of three-dimensional X-ray crystallography of globular proteins.
Abstract: Publisher Summary This chapter investigates the anatomy and taxonomy of protein structures. A protein is a polypeptide chain made up of amino acid residues linked together in a definite sequence. Amino acids are “handed,” and naturally occurring proteins contain only L-amino acids. A simple mnemonic for that purpose is the “corncrib.” The sequence of side chains determines all that is unique about a particular protein, including its biological function and its specific three-dimensional structure. The major possible routes to knowledge of three-dimensional protein structure are prediction from the amino acid sequence and analysis of spectroscopic measurements such as circular dichroism, laser Raman spectroscopy, and nuclear magnetic resonance. The analysis and discussion of protein structure is based on the results of three-dimensional X-ray crystallography of globular proteins. The basic elements of protein structures are discussed. The most useful level at which protein structures are to be categorized is the domain, as there are many cases of multiple-domain proteins in which each separate domain resembles other entire smaller proteins. The simplest type of stable protein structure consists of polypeptide backbone wrapped more or less uniformly around the outside of a single hydrophobic core. The outline of the taxonomy is also provided in the chapter.
3,201 citations
Cites background from "The packing of α-helices: simple co..."
...[{sidebar: Analyses of Helix-Helix Packing}] ***The ways in which α-helices pack against one another were initially described by Crick (1953) as “knobs into holes” side chain packing which could work at either a shallow lefthanded crossing angle or a steeper right-handed one....
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TL;DR: This chapter considers the parameters that are required for an adequate description of a polypeptide chain and the mathematical method of utilizing these parameters for calculating the coordinates of all the atoms in a suitable frame of reference so that all the interatomic distances, and bond angles, can be calculated and their consequences worked out.
Abstract: Publisher Summary This chapter deals with the recent developments regarding the description and nature of the conformation of proteins and polypeptides with special reference to the stereochemical aspects of the problem. This chapter considers the parameters that are required for an adequate description of a polypeptide chain. This chapter focuses the attention on what may be called “internal parameters”—that is, those which can be defined in terms of the relationships among atoms or units that form the building blocks of the polypeptide chains. This chapter also provides an account of the mathematical method of utilizing these parameters for calculating the coordinates of all the atoms in a suitable frame of reference, so that all the interatomic distances, and bond angles, can be calculated and their consequences worked out. This chapter observes conformations in amino acids, peptides, polypeptides, and proteins.
2,802 citations
TL;DR: The X-ray crystal structure of a core synaptic fusion complex containing syntaxin-1A, synaptobrevin-II and SNAP-25B reveals a highly twisted and parallel four-helix bundle that differs from the bundles described for the haemagglutinin and HIV/SIV gp41 membrane-fusion proteins.
Abstract: The evolutionarily conserved SNARE proteins and their complexes are involved in the fusion of vesicles with their target membranes; however, the overall organization and structural details of these complexes are unknown. Here we report the X-ray crystal structure at 2.4 A resolution of a core synaptic fusion complex containing syntaxin-1 A, synaptobrevin-II and SNAP-25B. The structure reveals a highly twisted and parallel four-helix bundle that differs from the bundles described for the haemagglutinin and HIV/SIV gp41 membrane-fusion proteins. Conserved leucine-zipper-like layers are found at the centre of the synaptic fusion complex. Embedded within these leucine-zipper layers is an ionic layer consisting of an arginine and three glutamine residues contributed from each of the four alpha-helices. These residues are highly conserved across the entire SNARE family. The regions flanking the leucine-zipper-like layers contain a hydrophobic core similar to that of more general four-helix-bundle proteins. The surface of the synaptic fusion complex is highly grooved and possesses distinct hydrophilic, hydrophobic and charged regions. These characteristics may be important for membrane fusion and for the binding of regulatory factors affecting neurotransmission.
2,381 citations
TL;DR: The crystal structure of this complex, composed of the peptides N36 and C34, is a six-helical bundle that shows striking similarity to the low-pH-induced conformation of influenza hemagglutinin and likely represents the core of fusion-active gp41.
2,162 citations
Cites background from "The packing of α-helices: simple co..."
...(holes) between four residues of an adjacent helix (Crick, 1953; O’Shea et al., 1991)....
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TL;DR: A 7-Å resolution map of the purple membrane has been obtained by electron microscopy of tilted, unstained specimens and shows that Lipid bilayer regions fill the spaces between the protein molecules.
Abstract: A 7-A resolution map of the purple membrane has been obtained by electron microscopy of tilted, unstained specimens. The protein in the membrane contains seven, closely packed, alpha-helical segments which extend roughly perpendicular to the plane of the membrane for most of its width. Lipid bilayer regions fill the spaces between the protein molecules.
2,114 citations