Adhesion controls bacterial actin polymerization-based movement

Area of Science:

• Microbial pathogenesis
• Biophysics
• Cell biology

Background:

• Listeria monocytogenes uses host-cell actin polymerization for movement within host cells.
• Understanding the biophysical mechanisms of this actin-based motility is crucial for deciphering infectious processes.

Purpose of the Study:

• To differentiate between biophysical models of Listeria monocytogenes actin-based motility.
• To investigate the role of temperature and cytoskeletal protein interactions in bacterial propulsion.

Main Methods:

• High-throughput tracking of individual bacterial movement under varying temperatures.
• Analysis of bacterial speed using the Arrhenius rate law.
• Investigating mutant bacteria and diluted cellular extracts.

Main Results:

• Bacterial speed strongly correlates with temperature, following the Arrhenius rate law.
• A "rate compensation effect" was observed, where the prefactor A varied exponentially with activation energy E(a).
• Mutant bacteria and diluted environments showed additive increases in E(a), suggesting a bond-breakage model.

Conclusions:

• Bacterial propulsion is driven by thermally induced, cooperative breakage of surface adhesive bonds, rather than solely actin polymerization.
• This model accurately predicts the negative correlation between speed and actin gel density.
• Bacterial speed is primarily influenced by adhesion dynamics, offering insights into cytoskeletal protein regulation of cell movement.