Motor-driven intracellular transport powers bacterial gliding motility
Mingzhai Sun a,1, Morgane Wartel b,c,1, Eric Cascales d, Joshua W. Shaevitz a,e,2, and Tâm Mignot b,c,2
-Author Affiliations
aLewis-Sigler Institute for Integrative Genomics and
eDepartment of Physics, Princeton University, Princeton, NJ 08540;
bLaboratoire de Chimie Bactérienne, Centre National de la Recherche Scientifique, Unité Propre de Recherche 9043,
cInstitut de Microbiologie de la Méditerranée, Université Aix-Marseille, Marseille Cédex 13402, France; and
dLaboratoire Ingénierie des Systèmes Macromoléculaires, Centre National de la Recherche Scientifique, Unité Propre de Recherche 9027, Institut de Microbiologie de la Méditerranée, Université Aix-Marseille, Marseille Cédex 13402, France
Edited by Thomas J. Silhavy, Princeton University, Princeton, NJ, and approved March 14, 2011 (received for review January 21, 2011)
Abstract
Protein-directed intracellular transport has not been observed in bacteria despite the existence of dynamic protein localization and a complex cytoskeleton. However, protein trafficking has clear potential uses for important cellular processes such as growth, development, chromosome segregation, and motility. Conflicting models have been proposed to explain Myxococcus xanthus motility on solid surfaces, some favoring secretion engines at the rear of cells and others evoking an unknown class of molecular motors distributed along the cell body. Through a combination of fluorescence imaging, force microscopy, and genetic manipulation, we show that membrane-bound cytoplasmic complexes consisting of motor and regulatory proteins are directionally transported down the axis of a cell at constant velocity. This intracellular motion is transmitted to the exterior of the cell and converted to traction forces on the substrate. Thus, this study demonstrates the existence of a conserved class of processive intracellular motors in bacteria and shows how these motors have been adapted to produce cell motility.
murein cluster B, proton motive force
Footnotes
1M.S. and M.W. contributed equally to this work.
2To whom correspondence may be addressed. E-mail:shaevitz@princeton.edu or tmignot@ifr88.cnrs-mrs.fr.
Author contributions: M.S., M.W., J.W.S., and T.M. designed research; M.S., M.W., and E.C. performed research; M.S., M.W., J.W.S., and T.M. analyzed data; and M.S., M.W., J.W.S., and T.M. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at
Freely available online through the PNAS open access option.
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