Biology subjects

Santen, L.

Publications and source records attributed to Santen, L..

2 recordsLinked to original sources

bioRxiv2021

The adhesion capability of S. aureus cells is heterogeneously distributed over the cell envelope

Understanding and controlling microbial adhesion is an important biomedical problem. However, many properties of the adhesion process of bacteria are still unknown, for example the distribution of adhesive strength over the cell wall. While a patchy colloid model for adhesion has been developed recently for Gram-negative Escherichia coli cells, a comparable model for Grampositive cells is unknown. Here, we use single-cell force spectroscopy to measure the adhesion of Staphylococcus aureus at different positions on tailored surfaces. We find heterogeneous adhesion profiles with varying degrees of intensity. By comparing these results to simulations, we find that locally increased adhesion can be explained by several distinct spots of high adhesion capabilities, similar to the patchy colloid model. Only for the underlying profile without local adhesive spots simple geometric considerations are insufficient. Rather, strong angle-dependent molecule-substratum interactions are necessary to explain the bathtub-like adhesion profiles seen for Staphylococcus aureus on a sinusoidal surface. We discuss implications of our results for the development of new materials and the design and analysis of future studies.

biophysics↗

bioRxiv2020

Stable tug-of-war between kinesin-1 and cytoplasmic dynein upon different ATP and roadblock concentrations

The maintenance of intracellular processes like organelle transport and cell division depend on bidirectional movement along microtubules. These processes typically require kinesin and dynein motor proteins which move with opposite directionality. Because both types of motors are often simultaneously bound to the cargo, regulatory mechanisms are required to ensure controlled directional transport. Recently, it has been shown that parameters like mechanical motor activation, ATP concentration and roadblocks on the microtubule surface differentially influence the activity of kinesin and dynein motors in distinct manners. However, how these parameters affect bidirectional transport systems has not been studied. Here, we investigate the regulatory influence of these three parameter using in vitro gliding motility assays and stochastic simulations. We find that the number of active kinesin and dynein motors determines the transport direction and velocity, but that variations in ATP concentration and roadblock density have no significant effect. Thus, factors influencing the force balance between opposite motors appear to be important, whereas the detailed stepping kinetics and bypassing capabilities of the motors have only little effect.

biophysics↗