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

A random trajectory, representing an effector protein's movement, confined to a disk(A) or sphere (B) with radius . The trajectory, assumed to be Brownian here, is shown by the blue trace. The 10 equidistant red circles in panel (A) and 12 red spheres in panel (B) are the target sites, representing the needle complex bases, whose centroids are placed on the boundary of the confining domain. We label their radius by the parameter .
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3412870&req=5

pone-0041421-g001: A random trajectory, representing an effector protein's movement, confined to a disk(A) or sphere (B) with radius . The trajectory, assumed to be Brownian here, is shown by the blue trace. The 10 equidistant red circles in panel (A) and 12 red spheres in panel (B) are the target sites, representing the needle complex bases, whose centroids are placed on the boundary of the confining domain. We label their radius by the parameter .

Mentions: We initially represent an effector as a Brownian particle moving within a circular domain. More specifically, we consider two different situations: the first one is a particle which performs a 2d Brownian motion in a disk-shaped domain (Fig. 1A) and the second one is a 3d motion in a sphere (Fig. 1B). When a particle reach the boundary region it is either reflected or absorbed by any of the targets on the boundary (small circular red dots in Fig. 1) and exit. The targets represent a simplified model of the actual needle complex base [12] and are shaped as disks or spheres, depending on the dimensions of the bounding domain. Each target has its centre point residing on the domain boundary and we characterize its size by the radius ranging from 15 to 150 Å. Moreover, the full domain size is characterized by a radius with values from 0.5 to 1.1 m (details about the choice of these values are given in Materials and Methods).


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

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

A random trajectory, representing an effector protein's movement, confined to a disk(A) or sphere (B) with radius . The trajectory, assumed to be Brownian here, is shown by the blue trace. The 10 equidistant red circles in panel (A) and 12 red spheres in panel (B) are the target sites, representing the needle complex bases, whose centroids are placed on the boundary of the confining domain. We label their radius by the parameter .
© Copyright Policy
Related In: Results  -  Collection

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

pone-0041421-g001: A random trajectory, representing an effector protein's movement, confined to a disk(A) or sphere (B) with radius . The trajectory, assumed to be Brownian here, is shown by the blue trace. The 10 equidistant red circles in panel (A) and 12 red spheres in panel (B) are the target sites, representing the needle complex bases, whose centroids are placed on the boundary of the confining domain. We label their radius by the parameter .
Mentions: We initially represent an effector as a Brownian particle moving within a circular domain. More specifically, we consider two different situations: the first one is a particle which performs a 2d Brownian motion in a disk-shaped domain (Fig. 1A) and the second one is a 3d motion in a sphere (Fig. 1B). When a particle reach the boundary region it is either reflected or absorbed by any of the targets on the boundary (small circular red dots in Fig. 1) and exit. The targets represent a simplified model of the actual needle complex base [12] and are shaped as disks or spheres, depending on the dimensions of the bounding domain. Each target has its centre point residing on the domain boundary and we characterize its size by the radius ranging from 15 to 150 Å. Moreover, the full domain size is characterized by a radius with values from 0.5 to 1.1 m (details about the choice of these values are given in Materials and Methods).

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