Limits...
Bacterial secretion and the role of diffusive and subdiffusive first passage processes.

Marten F, Tsaneva-Atanasova K, Giuggioli L - PLoS ONE (2012)

Bottom Line: By funneling protein effectors through needle complexes located on the cellular membrane, bacteria are able to infect host cells during type III secretion events.As a result, theoretical predictions of secretion times are still lacking.Here we provide a model that quantifies, depending on the transport characteristics within bacterial cytoplasm, the amount of time for a protein effector to reach either of the available needle complexes.

View Article: PubMed Central - PubMed

Affiliation: Department of Engineering Mathematics, University of Bristol, Bristol, United Kingdom.

ABSTRACT
By funneling protein effectors through needle complexes located on the cellular membrane, bacteria are able to infect host cells during type III secretion events. The spatio-temporal mechanisms through which these events occur are however not fully understood, due in part to the inherent challenges in tracking single molecules moving within an intracellular medium. As a result, theoretical predictions of secretion times are still lacking. Here we provide a model that quantifies, depending on the transport characteristics within bacterial cytoplasm, the amount of time for a protein effector to reach either of the available needle complexes. Using parameters from Shigella flexneri we are able to test the role that translocators might have to activate the needle complexes and offer semi-quantitative explanations of recent experimental observations.

Show MeSH

Related in: MedlinePlus

Dynamics of 100 sub-diffusive effectors escaping from a sphere with radius   = 0.5 m and  targets on the boundary.Left panel: contour plot of the time (in seconds) until the first 50 random walkers have escaped from the sphere (see legend) as a function of the target radius  and sub-diffusion coefficient . Right panel: average escape time (in seconds) of all 100 effectors (see legend) as a function of the target radius  and sub-diffusion coefficient .
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3412870&req=5

pone-0041421-g007: Dynamics of 100 sub-diffusive effectors escaping from a sphere with radius  = 0.5 m and targets on the boundary.Left panel: contour plot of the time (in seconds) until the first 50 random walkers have escaped from the sphere (see legend) as a function of the target radius and sub-diffusion coefficient . Right panel: average escape time (in seconds) of all 100 effectors (see legend) as a function of the target radius and sub-diffusion coefficient .

Mentions: The inside of a cell is a watery but crowded compartment with a variety of molecules and internal structures [2]. As a result, the movement of certain proteins in the cytoplasm may display kinetics slower than diffusion as observed e.g. for mRNA in the experiments by [21]. To represent this scenario in our model, we study a situation in which the effectors in the sphere also move in a sub-diffusive manner. We set the sphere radius to 0.5 m and we place targets on the boundary. For simplicity, we assume that all needle complexes are active escape channels (no ‘translocator’ is necessary) and we put 100 sub-diffusive effectors at random locations. For each set of values of the sub-diffusion coefficient and target radius we compute two quantities: (1) the time until 50 effectors have left the sphere and (2) the average secretion time of all 100 effectors. Both quantities are displayed by a colour map, in the left and right panel of Fig. 7 respectively.


Bacterial secretion and the role of diffusive and subdiffusive first passage processes.

Marten F, Tsaneva-Atanasova K, Giuggioli L - PLoS ONE (2012)

Dynamics of 100 sub-diffusive effectors escaping from a sphere with radius   = 0.5 m and  targets on the boundary.Left panel: contour plot of the time (in seconds) until the first 50 random walkers have escaped from the sphere (see legend) as a function of the target radius  and sub-diffusion coefficient . Right panel: average escape time (in seconds) of all 100 effectors (see legend) as a function of the target radius  and sub-diffusion coefficient .
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3412870&req=5

pone-0041421-g007: Dynamics of 100 sub-diffusive effectors escaping from a sphere with radius  = 0.5 m and targets on the boundary.Left panel: contour plot of the time (in seconds) until the first 50 random walkers have escaped from the sphere (see legend) as a function of the target radius and sub-diffusion coefficient . Right panel: average escape time (in seconds) of all 100 effectors (see legend) as a function of the target radius and sub-diffusion coefficient .
Mentions: The inside of a cell is a watery but crowded compartment with a variety of molecules and internal structures [2]. As a result, the movement of certain proteins in the cytoplasm may display kinetics slower than diffusion as observed e.g. for mRNA in the experiments by [21]. To represent this scenario in our model, we study a situation in which the effectors in the sphere also move in a sub-diffusive manner. We set the sphere radius to 0.5 m and we place targets on the boundary. For simplicity, we assume that all needle complexes are active escape channels (no ‘translocator’ is necessary) and we put 100 sub-diffusive effectors at random locations. For each set of values of the sub-diffusion coefficient and target radius we compute two quantities: (1) the time until 50 effectors have left the sphere and (2) the average secretion time of all 100 effectors. Both quantities are displayed by a colour map, in the left and right panel of Fig. 7 respectively.

Bottom Line: By funneling protein effectors through needle complexes located on the cellular membrane, bacteria are able to infect host cells during type III secretion events.As a result, theoretical predictions of secretion times are still lacking.Here we provide a model that quantifies, depending on the transport characteristics within bacterial cytoplasm, the amount of time for a protein effector to reach either of the available needle complexes.

View Article: PubMed Central - PubMed

Affiliation: Department of Engineering Mathematics, University of Bristol, Bristol, United Kingdom.

ABSTRACT
By funneling protein effectors through needle complexes located on the cellular membrane, bacteria are able to infect host cells during type III secretion events. The spatio-temporal mechanisms through which these events occur are however not fully understood, due in part to the inherent challenges in tracking single molecules moving within an intracellular medium. As a result, theoretical predictions of secretion times are still lacking. Here we provide a model that quantifies, depending on the transport characteristics within bacterial cytoplasm, the amount of time for a protein effector to reach either of the available needle complexes. Using parameters from Shigella flexneri we are able to test the role that translocators might have to activate the needle complexes and offer semi-quantitative explanations of recent experimental observations.

Show MeSH
Related in: MedlinePlus