Extracting the stepping dynamics of molecular motors in living cells from trajectories of single particles

A BRUNO, L. BRUNO Y V. LEVI.

CELL BIOCHEMISTRY AND BIOPHYSICS

HUMANA PRESS INC

Lugar: Oregon; Año: 2013 vol. 65 p. 1 - 11

1085-9195

Molecular motors are responsible of transportinga wide variety of cargos in the cytoplasm. Currentefforts are oriented to characterize the biophysical propertiesof motors in cells with the aim of elucidating themechanisms of these nanomachines in the complex cellularenvironment. In this study, we present an algorithmdesigned to extract motor step sizes and dwell timesbetween steps from trajectories of motors or cargoes drivenby motors in cells. The algorithm is based on finding patternsin the trajectory compatible with the behaviorexpected for a motor step, i.e., a region of confined motionfollowed by a jump in the position to another region ofconfined motion with similar characteristics to the previousone. We show that this algorithm allows the analysis of 2Dtrajectories even if they present complex motion patternssuch as active transport interspersed with diffusion anddoes not require the assumption of a given step size ordwell period. The confidence on the step detection can beeasily obtained and allows the evaluation of the confidenceof the dwell and step size distributions. To illustrate thepossible applications of this algorithm, we analyzed trajectoriesof myosin-V driven organelles in living cells.