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The bacterial flagellar filament is a helical propeller for bacterial locomotion. It is a helical assembly of a single protein, flagellin, and its tubular structure is formed by 11 protofilaments in two distinct conformations, L- and R-type, for supercoiling. The X-ray crystal structure of a flagellin fragment lacking about 100 terminal residues revealed(More)
BACKGROUND KaiA, KaiB and KaiC are cyanobacterial circadian clock proteins. KaiC contains two ATP/GTP-binding Walker's motif As, and mutations in these regions affect the clock oscillations. RESULTS ATP induced the hexamerization of KaiC. The Km value for the ATP for the hexamerization was 1.9 micro m. Triphosphate nucleotides bound to the two Walker's(More)
The bacterial flagellar filament is a helical propeller rotated by the flagellar motor for bacterial locomotion. The filament is a supercoiled assembly of a single protein, flagellin, and is formed by 11 protofilaments. For bacterial taxis, the reversal of motor rotation switches the supercoil between left- and right-handed, both of which arise from(More)
Efficiency of interspecies prion transmission decreases as the primary structures of the infectious proteins diverge. Yet, a single prion protein can misfold into multiple infectious conformations, and such differences in "strain conformation" also alter infection specificity. Here, we explored the relationship between prion strains and species barriers by(More)
The FliF ring is the base for self-assembly of the bacterial flagellum and the FliF/FliG ring complex is the core of the rotor of the flagellar motor. We report the structures of these two ring complexes obtained by electron cryomicroscopy and single-particle image analysis at 22A and 25A resolution, respectively. Direct comparison of these structures with(More)
The amplitude contrast of frozen-hydrated biological samples was measured using the bacterial flagellar filament embedded in vitreous ice at an accelerating voltage of 300kV. From the mean radial amplitude spectra of overfocused images, amplitude contrast was estimated to be 6.9+/-1.9% and 2.7+/-1.0% of the whole contrast at the low spatial frequency range(More)
Although many people have expressed alarm that we are witnessing a mass extinction, few projections have been quantified, owing to limited availability of time-series data on threatened organisms, especially plants. To quantify the risk of extinction, we need to monitor changes in population size over time for as many species as possible. Here, we present(More)
Sweet and umami tastes are perceived by T1r taste receptors in oral cavity. T1rs are class C G-protein coupled receptors (GPCRs), and the extracellular ligand binding domains (LBDs) of T1r1/T1r3 and T1r2/T1r3 heterodimers are responsible for binding of chemical substances eliciting umami or sweet taste. However, molecular analyses of T1r have been hampered(More)
We report a crystal structure of Hfq and catalase HPII from Escherichia coli. The post-transcriptional regulator Hfq plays a key role in the survival of bacteria under stress. A small non-coding RNA (sRNA) DsrA is required for translation of the stationary phase sigma factor RpoS, which is the central regulator of the general stress response. Hfq(More)
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