APh161 - Lecture 15: APh161 - Lecture 15: Molecular Motors Molecular Motors Rob Phillips California Institute of Technology
Jan 20, 2016
APh161 - Lecture 15: Molecular APh161 - Lecture 15: Molecular MotorsMotors
Rob PhillipsCalifornia Institute of Technology
Mitotic Spindle Organization
Cilia and Flagella Assembly and Dynamics
Formation of Golgi and ER
Networks
Vesicle Transport
Molecular MotorsMolecular Motors
Rogues Gallery of Motor Action: Rotary Rogues Gallery of Motor Action: Rotary
MotorsMotors
Show Berg movie Show Yasuda et al. movie
Rogues Gallery of Motor Action: Rogues Gallery of Motor Action:
TranslocationTranslocation
Rogues Gallery of Motor Action: Rogues Gallery of Motor Action:
Translational Motor 1Translational Motor 1
Rogues Gallery of Motor Action: Rogues Gallery of Motor Action:
Translational Motor 2 - MusclesTranslational Motor 2 - Muscles
See Hugh Huxley review on website
Rogues Gallery of Motor Action: Rogues Gallery of Motor Action:
Translational Motor 2 - MusclesTranslational Motor 2 - Muscles
Heuser lab – Washington University
Organellar Transport Organellar Transport
(Hirokawa, Science 1998)
Rogues Gallery of Motor Action: Rogues Gallery of Motor Action:
Translational Motor 2Translational Motor 2
Myosin V
Speed: 350 nm/s ATPase: 5.0 1/s
Kinesin
Speed: 850 nm/s ATPase: 44.0 1/s
Dynein
Speed: -1250 nm/s ATPase: 2.0 1/s
**ALL INVOLVED IN VESICLE TRANSPORT**
Translational MotorsTranslational Motors
How We Know: Gliding Motility AssaysHow We Know: Gliding Motility Assays
Show Vale movie
Dynamics of Molecular MotorsDynamics of Molecular Motors
Science, Vol 300, Issue 5628, 2061-2065, 27 June 2003 - Yildiz et al.
Show Gelles, Selvin movie
Stepping KineticsStepping Kinetics
Spudich et al., PNAS 2000
Kinesin DataKinesin Data
Fig. 3. Kinesin velocity as a function of [ATP] under external loads, F, fixed by a force clamp. The plots, from the top down, are for F = 0, 1.05, 3.59, 4.60, and 5.63 pN, respectively. Data from Block and colleagues (9): solid curves, N = 2 fits; dashed curves, N = 2 predictions (see text)
(Fisher and Kolomeisky, PNAS)
Kinesin Data continuedKinesin Data continued
Fig. 4. Fits to the data of Block and colleagues (9) (and predictions) for velocity as a function of load for fixed concentrations of ATP. Note the inflection points at low [ATP] and convex profile at saturating [ATP].
(Fisher and Kolomeisky, PNAS)
Kinesin Randomness DataKinesin Randomness Data
Fig. 5. Randomness data from Block and colleagues (9) and theoretical fits (A) as a function of external load, F, at fixed [ATP] (note that the two data points at F 5.7 pN and [ATP] = 2 mM appear separately in Block and coworkers: see figure 4 a and b of ref. 9, respectively) and (B) as a function of [ATP] at fixed loads of, from top down, F = 5.69 pN ( ), 5.35 and 4.60 pN (dashed-line predictions), 3.59 pN ( ), and 1.05 pN ( ).
Motors and StatesMotors and States
What do we mean by the states?What do we mean by the states?
Translocation MotorsTranslocation Motors
Measurements on Rate of DNA EjectionMeasurements on Rate of DNA Ejection
DNA injection from T5 into vesicle
Injection rate in λ
(Baldeschweiler et al.) (Bohm et al.)
Measurements on Rate of DNA EjectionMeasurements on Rate of DNA Ejection
Phage Hypothesized Mechanism
Genome Length (kbp)
Ejection time (sec)
Av. Ejection rate (kbp/sec)
lambda Pressure 48.5 60 0.8
T4 Pressure 169 30 5.6
T7 Enzyme 40 600 0.06
T5 Pressure+
Enzyme
121 360 0.3
phi29 Pressure+ Enzyme 19 1800 0.05
Calculating the Ejection Time Calculating the Ejection Time Calculating the Ejection Time Calculating the Ejection Time
The mean first passage time is
The Time of EjectionThe Time of Ejection
receptor
vesicle
No protein interactions