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

Number of effectors left in the sphere as function of time from a bacterium of spherical shape with radius   = 0.5 m.Panel A represents the case of 92 needle complexes distributed uniformly on the sphere. Panel B represents the case of 25 needle complexes distributed uniformly only in the upper hemisphere. In both cases the needle complexes have radius  = 50 Å. The solid black curves represent the secretion of diffusive effectors (I), the dash and dash-dotted lines represent the secretion of diffusive effectors with sequentially activated needle complexes (II), and the blue line represents the secretion of subdiffusive effectors (III).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3412870&req=5

pone-0041421-g006: Number of effectors left in the sphere as function of time from a bacterium of spherical shape with radius  = 0.5 m.Panel A represents the case of 92 needle complexes distributed uniformly on the sphere. Panel B represents the case of 25 needle complexes distributed uniformly only in the upper hemisphere. In both cases the needle complexes have radius  = 50 Å. The solid black curves represent the secretion of diffusive effectors (I), the dash and dash-dotted lines represent the secretion of diffusive effectors with sequentially activated needle complexes (II), and the blue line represents the secretion of subdiffusive effectors (III).

Mentions: From Fig. 5F one notices that, when a cell has targets, a value of  = 0.002 m/s is necessary to have  = 100 seconds. Those predictions concur with the solid black curve plotted in Fig. 6A where the number of effectors left in the sphere is drawn as a function of time. The secretion curve, generated through stochastic simulations (see Materials and Methods for the details), displays in fact an exponential decay whose mean is around 100 seconds.


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

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

Number of effectors left in the sphere as function of time from a bacterium of spherical shape with radius   = 0.5 m.Panel A represents the case of 92 needle complexes distributed uniformly on the sphere. Panel B represents the case of 25 needle complexes distributed uniformly only in the upper hemisphere. In both cases the needle complexes have radius  = 50 Å. The solid black curves represent the secretion of diffusive effectors (I), the dash and dash-dotted lines represent the secretion of diffusive effectors with sequentially activated needle complexes (II), and the blue line represents the secretion of subdiffusive effectors (III).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0041421-g006: Number of effectors left in the sphere as function of time from a bacterium of spherical shape with radius  = 0.5 m.Panel A represents the case of 92 needle complexes distributed uniformly on the sphere. Panel B represents the case of 25 needle complexes distributed uniformly only in the upper hemisphere. In both cases the needle complexes have radius  = 50 Å. The solid black curves represent the secretion of diffusive effectors (I), the dash and dash-dotted lines represent the secretion of diffusive effectors with sequentially activated needle complexes (II), and the blue line represents the secretion of subdiffusive effectors (III).
Mentions: From Fig. 5F one notices that, when a cell has targets, a value of  = 0.002 m/s is necessary to have  = 100 seconds. Those predictions concur with the solid black curve plotted in Fig. 6A where the number of effectors left in the sphere is drawn as a function of time. The secretion curve, generated through stochastic simulations (see Materials and Methods for the details), displays in fact an exponential decay whose mean is around 100 seconds.

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