Vorlesung Biophysik I - Molekulare Biophysik Kalbitzer/Kremer/Ziegler

Transcription

1 Vorlesung Biophysik I - Molekulare Biophysik Kalbitzer/Kremer/Ziegler Zelle Biologische Makromoleküle I Biologische Makromoleküle II Nukleinsäuren-Origami (DNA, RNA) Aminosäuren-Origami (Protein-Nanotechnologie) Molekulare Motoren Methoden zur Strukturbestimmung: Magnetische Resonanzspektroskopie I - Grundlagen Magnetische Resonanzspektroskopie II - Mehrdimensionale NMR- Spektroskopie Magnetische Resonanzspektroskopie III Proteinstrukturbestimmung, Dynamik und Bewegung, ESR-Spektroskopie Röntgenstrukturanalyse I Streuung von Wellen, Faltungstheorem, Pattersonfunktion, Phasenproblem Röntgenstrukturanalyse II - Synchrotronstrahlung, zeitaufgelöste Kristallographie Röntgenkleinwinkelstreuung Elektronenmikroskopie I Elektronenoptik, Kontrastentstehung und Bildinformation Elektronenmikroskopie II Kristalline Objekte, Tomographie Klausur

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5 Scanning tunnelling microscopes (STMs) have been pivotal to studies of atomic-scale motion. a, b, At first, STMs were used to follow the diffusion of atoms (a) and molecules (b) on surfaces. Red arrows indicate movement of atoms or molecules; the atomic structure of the end of the STM tip is shown. c, d, STMs were then used to position atoms into precise structures (c) and to push molecules to study nanometre-scale interactions (d). e, Kudernac et al. 1 have now used an STM as an energy source for molecular motion the STM provided electrons (blue arrow) to drive car-like molecules with four motorized 'wheels' (purple) across a surface. Black arrows indicate the turning of the wheels.

6 Figure 1: Structure of the four-wheeled molecule.

7 Control over motion by the geometries of the four motors. T Kudernac et al. Nature 479, (2011) doi: /nature10587

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16 Neurobiology Ion channels as molecular machines Adapted from the poster: The Nobel Prize in Chemistry 2003: Peter Agre and Roderick MacKinnon.

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19 Motor proteins in the cell. (A) Representation of FOF1-ATPase (B) Representation of the bacterial flagellar motor (image courtesy of Keiichi Namba, Osaka University). Inset shows an electron microscopy image of the motor

20 (C) Conventional kinesin and dynein transport cargo in opposite directions along microtubules (D) Kinesin is a processive motor, consisting of two heads, that walks in alternate steps of 8 nm along the microtubule

21 (E) Muscle contraction is caused by the sliding of interdigitated actin and myosin filaments in a sarcomere unit. The nonprocessive myosin II motor detaches after each power stroke so as not to impede the further sliding of the actin filament caused by other mysosins (F) RNA polymerase moves along a double-stranded DNA template, transcribing a RNA copy

22 Motor proteins in nanotechnology. (A) An F1 -ATPase powered nanopropeller Fluorescence images (133-ms interval) are from the earlier experiment that first demonstrated the rotary motion of the F1-ATPase motor by using a fluorescent actin filament connected to the stalk (B) A microrotor (20-mm diameter) powered by bacteria that adhere to the rotor and glide unidirectionally through the track. Photo images show the clockwise rotation of the rotor

23 (C) Schematic of kinesin motor proteins adsorbed to a surface propelling a microtubule shuttle, which binds cargo such as a DNA molecule The fluorescence image shows kinesin-propelled microtubules moving through open polyurethane channels The velocity of microtubules is typically about 1 mm/s, whereas actin motility can reach speeds up to 10 mm/s.

24 Biomotor-driven transport. (A) Evolution in the confinement of motility. (I) On flat surfaces, the motion of filaments is in random directions (fluorescence image at bottom). (II) To confine the motion, people initially used (top) chemical patterning of motors (as indicated by red x s) or (middle) topographical structuring of the substrates. (Bottom) Scanning electron microscopy (SEM) image shows microfabricated channels in SiO2. (III) A combination of both methods proved more effective. Bottom image shows time-integrated fluorescence of actin filaments, which are mobile exclusively in the letter-shaped tracks (IV) The use of submicrometer fluidic channels offers threedimensional (3D) confinement. (Bottom) SEM image of a closed channel.

25 (B) Arrow-shaped structures rectify the motility. Initially, the amount of microtubules is equal in both reservoirs, but after 18 min most microtubules have collected in the left reservoir (C) A kinesin-propelled microtubule binds to and stretches a DNA molecule attached to a gold post (D) Thermoresponsive polymers form a clever way of switching the motility on and off (E) An electric force is used to steer individual kinesin-propelled microtubules within an enclosed fluidic channel.

26 Prospects and future directions. (A) Fictitious motor-protein powered device that performs onchip sorting of materials, assembly of different components, and concentrating another component for enhanced detection. (B) Polymer vesicles containing bacteriorhodopsin and FOF1-ATP synthase create ATP from the light-driven proton gradient established over the membrane

27 (C) Artificial molecular motors are a new development. Upon illumination with UV light, organic molecules embedded in a liquid-crystal film induce a reorganization of the film texture, driving the rotation of a glass particle. Photo images taken with 15-s intervals

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51 Vorlesung Biophysik I - Molekulare Biophysik Kalbitzer/Kremer/Ziegler Zelle Biologische Makromoleküle I Biologische Makromoleküle II Nukleinsäuren-Origami (DNA, RNA) Aminosäuren-Origami (Protein-Nanotechnologie) Molekulare Motoren Methoden zur Strukturbestimmung: Magnetische Resonanzspektroskopie I - Grundlagen Magnetische Resonanzspektroskopie II - Mehrdimensionale NMR- Spektroskopie Magnetische Resonanzspektroskopie III Proteinstrukturbestimmung, Dynamik und Bewegung, ESR-Spektroskopie Röntgenstrukturanalyse I Streuung von Wellen, Faltungstheorem, Pattersonfunktion, Phasenproblem Röntgenstrukturanalyse II - Synchrotronstrahlung, zeitaufgelöste Kristallographie Röntgenkleinwinkelstreuung Elektronenmikroskopie I Elektronenoptik, Kontrastentstehung und Bildinformation Elektronenmikroskopie II Kristalline Objekte, Tomographie Klausur