Listeria monocytogenesActin-based Motility Varies Depending on Subcellular Location: A Kinematic Probe for Cytoarchitecture

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Abstract
Intracellular Listeria monocytogenes actin-based motility is characterized by significant individual variability, which can be influenced by cytoarchitecture. L. monocytogenes was used as a probe to transmit information about structural variation among subcellular domains defined by mitochondrial density. By analyzing the movement of a large population of L. monocytogenes in PtK2 cells, we found that mean speed and trajectory curvature were significantly larger for bacteria moving in mitochondria-containing domains (generally perinuclear) than for bacteria moving in mitochondria-free domains (generally peripheral). Analysis of bacteria that traversed both mitochondria-containing and mitochondria-free domains revealed that these motile differences were not intrinsic to bacteria themselves. Disruption of mitochondrial respiration did not affect bacterial mean speed, speed persistence, or trajectory curvature. In contrast, microtubule depolymerization lead to decreased mean speed per bacterium and increased mean speed persistence of L. monocytogenes moving in mitochondria-free domains compared with untreated cells. L. monocytogenes were also observed to physically collide with mitochondria and push them away from the bacterial path of motion, causing bacteria to slow down before rapidly resuming their speed. Our results show that subcellular domains along with microtubule depolymerization may influence the actin cytoskeleton to affect L. monocytogenes speed, speed persistence, and trajectory curvature.