APh161 - Lecture 15: Molecular Motors Rob Phillips California Institute of Technology.

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