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The dimerization domain of Escherichia coli ATP synthase b subunit forms an atypical parallel two-stranded coiled coil. Sequence analysis reveals an 11-residue abcdefghijk repeat characteristic of right-handed coiled coils, but no other naturally occurring parallel dimeric structure of this class has been identified. The arrangement of the helices was studied by their propensity to form interhelix disulfide linkages and analysis of the stability and shape of disulfide-linked dimers. Disulfides formed preferentially between cysteine residues in an a position of one helix and either of the adjacent h positions of the partner. Such heterodimers were far more stable to thermal denaturation than homodimers and, on the basis of gel-filtration chromatography studies, were similar in shape to both non-covalent dimers and dimers linked through flexible Gly(1-3)Cys C-terminal extensions. The results indicate a right-handed coiled-coil structure with intrinsic asymmetry, the two helices being offset rather than in register. A function for the right-handed coiled coil in rotational catalysis is proposed.
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http://dx.doi.org/10.1016/j.jmb.2006.09.028 | DOI Listing |
Clin Neurophysiol
September 2025
Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland.
Objective: The exact part of the motor cortex activated by transcranial magnetic stimulation (TMS) remains debatable. This study investigates the electric field (EF) distribution induced by TMS coils in personalized head models, focusing on group-level evaluation considering motor-evoked potential (MEP) latency differences.
Methods: Thirteen healthy right-handed men (mean age 22.
Acta Crystallogr D Struct Biol
May 2025
Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland.
Common bean (Phaseolus vulgaris) encodes three class 2 L-asparaginase enzymes: two potassium-dependent enzymes [PvAIII(K)-1 and PvAIII(K)-2] and a potassium-independent enzyme (PvAIII). Here, we present the crystal structure of PvAIII, which displays a rare P2 space-group symmetry and a unique pseudosymmetric 4-like double-helical packing. The asymmetric unit contains 32 protein chains (16 αβ units labeled A-P) organized into two right-handed coiled arrangements, each consisting of four PvAIII (αβ) dimers.
View Article and Find Full Text PDFChem Commun (Camb)
February 2025
Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune, Dr Homi Bhabha Road, Pune-411008, India.
A superhelix is a three-dimensional arrangement of a helix in which the helix is coiled around a common axis. Here, we are reporting a short 12-helix of α,γ-hybrid peptides terminated by metal binding ligands, self-assembled into a right-handed superhelix around a common axis in the presence of Cd(II) ions. Furthermore, these superhelices are assembled into hierarchical superhelical β-sheet-type structural motifs in single crystals.
View Article and Find Full Text PDFScience
July 2024
Universität Konstanz, Fachbereich Physik, 78464 Konstanz, Germany.
Chirality is a phenomenon with widespread relevance in fundamental physics, material science, chemistry, optics, and spectroscopy. In this work, we show that a free electron can be converted by the field cycles of laser light into a right-handed or left-handed coil of mass and charge. In contrast to phase-vortex beams, our electrons maintained a flat de Broglie wave but obtained their chirality from the shape of their expectation value in space and time.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
July 2024
Laboratory of Molecular Neurobiology and Biophysics, The Rockefeller University, New York, NY 10065.
In this study, we used cryoelectron microscopy to determine the structures of the Flotillin protein complex, part of the Stomatin, Prohibitin, Flotillin, and HflK/C (SPFH) superfamily, from cell-derived vesicles without detergents. It forms a right-handed helical barrel consisting of 22 pairs of Flotillin1 and Flotillin2 subunits, with a diameter of 32 nm at its wider end and 19 nm at its narrower end. Oligomerization is stabilized by the C terminus, which forms two helical layers linked by a β-strand, and coiled-coil domains that enable strong charge-charge intersubunit interactions.
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