Nano-Lab August Nano-Lab August 20032003

Nano-scale motorsNano-scale motors

Molecular MotorsMolecular Motors

Biological MotorsBiological Motors BackgroundBackground

Three types of linear stepper protein motorsThree types of linear stepper protein motors Linear stepper motor: KinesinLinear stepper motor: Kinesin Rotary propellers: bacterial flagellaRotary propellers: bacterial flagella

Laboratory made motorsLaboratory made motors UC BerkeleyUC Berkeley University of Edinburgh/BolognaUniversity of Edinburgh/Bologna Cornell/UCLACornell/UCLA

Future ProjectionsFuture Projections

BackgroundBackground Molecular motors are proteins that use ATP to carry Molecular motors are proteins that use ATP to carry

out coordinated movements within cells.out coordinated movements within cells. ATP hydrolysis is presumed to drive protein ATP hydrolysis is presumed to drive protein

conformation changes that result in sliding or conformation changes that result in sliding or walking movements.walking movements.

Molecular movement occurs along a “track”Molecular movement occurs along a “track” The “track”, either an actin filament or a micro The “track”, either an actin filament or a micro

tubule, is a helical polymer that has intrinsic polarity.tubule, is a helical polymer that has intrinsic polarity.

(-)(+)http://courses.nnu.edu/cm342jc/Term%20Projects/2001%20proj/collins.ppt

Linear Protein Motor TypesLinear Protein Motor Types

MYOSIN Moves toward

fast-growing (+) end of actin filaments.

DYNEINMoves toward slow-growing

(-) end of microtubules.

KINESINMoves generally toward

(+) end of microtubules.

http://courses.nnu.edu/cm342jc/Term%20Projects/2001%20proj/collins.ppt

Kinesin Kinesin Kinesin “walks” along the Kinesin “walks” along the

microtubule (MT) microtubule (MT) protofilament, stepping protofilament, stepping from one tubulin subunit from one tubulin subunit to the next.to the next.

Unidirectional motion is Unidirectional motion is produced by a produced by a pronounced pronounced conformational change in conformational change in kinesin’s “neck linker.”kinesin’s “neck linker.”

(Vale & Milligan, 2000)

~80Å

http://courses.nnu.edu/cm342jc/Term%20Projects/2001%20proj/collins.ppt

CATALYTIC CORE: allosteric domain containing MT and nucleotide binding regions.

NECK LINKER: motion is produced by conformational change.

COILED COlL: extends toward cargo.

1.) ATP binds to leading head, initiating docking of neck linker to tubulin.

http://courses.nnu.edu/cm342jc/Term%20Projects/2001%20proj/collins.ppt

Bacterial FlagellaBacterial Flagella

Molecular engine Molecular engine powered by the flow of powered by the flow of ions across the inner, or  ions across the inner, or  cytoplasmic, membrane cytoplasmic, membrane of a bacterial cell of a bacterial cell envelopeenvelope

Each motor drives a Each motor drives a protruding helical protruding helical filament, and the rotating filament, and the rotating filaments provide the filaments provide the propulsive force for cells propulsive force for cells to swim.  to swim. 

Artistic version of flagella motorhttp://www2.physics.ox.ac.uk/biophysics/research/flagellar.html

Bacterial FlagellaBacterial Flagella Ion flux is driven by an Ion flux is driven by an

electrochemical gradient electrochemical gradient controlled by H+ and Na+ controlled by H+ and Na+

This gradient consists of This gradient consists of a voltage component and a voltage component and a concentration a concentration componentcomponent

The inside of the cell is The inside of the cell is typically at an electrical typically at an electrical potential about 150mV potential about 150mV below the outside and below the outside and has a slightly lower has a slightly lower concentration of H+ or concentration of H+ or Na+ Na+

http://www2.physics.ox.ac.uk/biophysics/research/flagellar.htmlhttp://www.id.ucsb.edu/fscf/library/battson/stasis/4.html

Bacterial FlagellaBacterial Flagella Filaments rotate at Filaments rotate at

speeds up to 1000 Hz in speeds up to 1000 Hz in swimming cellsswimming cells

The rotating heart of the The rotating heart of the motor is a set of rings in motor is a set of rings in the cytoplasmic the cytoplasmic membranemembrane

This rotor is surrounded This rotor is surrounded by 8-16 torque by 8-16 torque generators, proteins MotA generators, proteins MotA and MotB, anchored in and MotB, anchored in the cell wall the cell wall

http://www2.physics.ox.ac.uk/biophysics/research/flagellar.html

Laboratory Nano-motorsLaboratory Nano-motors

UC Berkeley Gold Nano-motorUC Berkeley Gold Nano-motor

Gold rotor on a multilayered Gold rotor on a multilayered Carbon nano-tube shaftCarbon nano-tube shaft

The rotor, nano-tube anchors and The rotor, nano-tube anchors and stators were constructed around stators were constructed around the carbon nano-tube, using the carbon nano-tube, using electron beam lithography and electron beam lithography and silicon etching techniques, that had silicon etching techniques, that had been deposited on a silicon waferbeen deposited on a silicon wafer

http://www.berkeley.edu/news/media/releases/2003/07/23_motor.shtml

UC Berkeley Gold Nano-motorUC Berkeley Gold Nano-motor

Using an electric jolt to Using an electric jolt to jerk the rotor, the nested jerk the rotor, the nested nano-tube outer walls nano-tube outer walls were broken free were broken free allowing the rotor to spin allowing the rotor to spin on the nano-tube on the nano-tube “bearings”“bearings”

Motor is about 500 nm Motor is about 500 nm acrossacross

The rotor is between The rotor is between 100 and 300 nm long100 and 300 nm long

http://www.berkeley.edu/news/media/releases/2003/07/23_motor.shtml

UCLA/Cornell UniversityUCLA/Cornell University

Carlo MontemagnoCarlo Montemagno Nickel rotors about 700 Nickel rotors about 700

nm long are attached to nm long are attached to the shaft moleculethe shaft molecule

Shaft is rotated by the six Shaft is rotated by the six cylindrical structures and cylindrical structures and can be turned off or on by can be turned off or on by adding or removing zinc adding or removing zinc from the solutionfrom the solution

A histidine peptide allows A histidine peptide allows the molecular motor to the molecular motor to adhere to nanofabricated adhere to nanofabricated patterns of gold, copper patterns of gold, copper or nickelor nickel

Nanofabricated nickel post

http://www.news.cornell.edu/releases/sept99/bio_nano_mechanical.hrs.htmlhttp://www.sciam.com/article.cfm?articleID=000988D5-647B-1C75-9B81809EC588EF21&pageNumber=2&catID=4

University of Edinburgh/BolognaUniversity of Edinburgh/Bologna

Two smaller rings Two smaller rings move around the move around the larger “cycle” ringlarger “cycle” ring

Light, heat or Light, heat or chemical stimuli drive chemical stimuli drive the rings around the the rings around the cycle by altering the cycle by altering the properties of each properties of each chemically distinct chemically distinct sitesite

chemistry professor David A. Leigh University of Edinburghhttp://www.chem.ed.ac.uk/leigh/http://pubs.acs.org/cen/topstory/8128/8128notw9.htmlhttp://www.nanotechweb.org/articles/news/2/7/9/1

Future ProjectionsFuture Projectionshttp://bionano.rutgers.edu/Mavroidis_Final_Report.pdf