Nariman Naber

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Kinesin motors power many motile processes by converting ATP energy into unidirectional motion along microtubules. The force-generating and enzymatic properties of conventional kinesin have been extensively studied; however, the structural basis of movement is unknown. Here we have detected and visualized a large conformational change of an approximately(More)
A remarkable feature of prion biology is the strain phenomenon wherein prion particles apparently composed of the same protein lead to phenotypically distinct transmissible states. To reconcile the existence of strains with the 'protein-only' hypothesis of prion transmission, it has been proposed that a single protein can misfold into multiple distinct(More)
Crystal structures of the molecular motor kinesin show conformational variability in a structural element called the neck linker. Conformational change in the neck linker, initiated by ATP exchange, is thought to drive the movement of kinesin along the microtubule track. We use site-specific EPR measurements to show that when microtubules are absent, the(More)
Kinesin motors move on microtubules by a mechanism that involves a large, ATP-triggered conformational change in which a mechanical element called the neck linker docks onto the catalytic core, making contacts with the core throughout its length. Here, we investigate the thermodynamic properties of this conformational change using electron paramagnetic(More)
Evenly spaced nucleosomes directly correlate with condensed chromatin and gene silencing. The ATP-dependent chromatin assembly factor (ACF) forms such structures in vitro and is required for silencing in vivo. ACF generates and maintains nucleosome spacing by constantly moving a nucleosome towards the longer flanking DNA faster than the shorter flanking(More)
A hallmark of histone H3 lysine 9 (H3K9)-methylated heterochromatin, conserved from the fission yeast Schizosaccharomyces pombe to humans, is its ability to spread to adjacent genomic regions. Central to heterochromatin spread is heterochromatin protein 1 (HP1), which recognizes H3K9-methylated chromatin, oligomerizes and forms a versatile platform that(More)
The structure of glycerinated Lethocerus insect flight muscle fibers, relaxed by spin-labeled ATP and vanadate (Vi), was examined using X-ray diffraction, electron microscopy and electron paramagnetic resonance (e.p.r.) spectra. We obtained excellent relaxation of MgATP quality as determined by mechanical criteria, using vanadate trapping of 2' spin-labeled(More)
We have used spin-labeled ADP to investigate the dynamics of the nucleotide-binding pocket in a series of myosins, which have a range of velocities. Electron paramagnetic resonance spectroscopy reveals that the pocket is in equilibrium between open and closed conformations. In the absence of actin, the closed conformation is favored. When myosin binds(More)
We measured the nucleotide turnover rate of myosin in tarantula leg muscle fibers by observing single turnovers of the fluorescent nucleotide analog 2'-/3'-O-(N'-methylanthraniloyl)adenosine-5'-O-triphosphate, as monitored by the decrease in fluorescence when 2'-/3'-O-(N'-methylanthraniloyl)adenosine-5'-O-triphosphate (mantATP) is replaced by ATP in a chase(More)