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Title: Reversals and collisions optimize protein exchange in bacterial swarms

Authors:
; ; ; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1346773
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review E
Additional Journal Information:
Journal Volume: 95; Journal Issue: 3; Related Information: CHORUS Timestamp: 2017-03-13 22:16:55; Journal ID: ISSN 2470-0045
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English

Citation Formats

Amiri, Aboutaleb, Harvey, Cameron, Buchmann, Amy, Christley, Scott, Shrout, Joshua D., Aranson, Igor S., and Alber, Mark. Reversals and collisions optimize protein exchange in bacterial swarms. United States: N. p., 2017. Web. doi:10.1103/PhysRevE.95.032408.
Amiri, Aboutaleb, Harvey, Cameron, Buchmann, Amy, Christley, Scott, Shrout, Joshua D., Aranson, Igor S., & Alber, Mark. Reversals and collisions optimize protein exchange in bacterial swarms. United States. doi:10.1103/PhysRevE.95.032408.
Amiri, Aboutaleb, Harvey, Cameron, Buchmann, Amy, Christley, Scott, Shrout, Joshua D., Aranson, Igor S., and Alber, Mark. Mon . "Reversals and collisions optimize protein exchange in bacterial swarms". United States. doi:10.1103/PhysRevE.95.032408.
@article{osti_1346773,
title = {Reversals and collisions optimize protein exchange in bacterial swarms},
author = {Amiri, Aboutaleb and Harvey, Cameron and Buchmann, Amy and Christley, Scott and Shrout, Joshua D. and Aranson, Igor S. and Alber, Mark},
abstractNote = {},
doi = {10.1103/PhysRevE.95.032408},
journal = {Physical Review E},
number = 3,
volume = 95,
place = {United States},
year = {Mon Mar 13 00:00:00 EDT 2017},
month = {Mon Mar 13 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevE.95.032408

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  • Swarming groups of bacteria coordinate their behavior by self-organizing as a population to move over surfaces in search of nutrients and optimal niches for colonization. Many open questions remain about the cues used by swarming bacteria to achieve this self-organization. While chemical cue signaling known as quorum sensing is well-described, swarming bacteria often act and coordinate on time scales that could not be achieved via these extracellular quorum sensing cues. Here, cell-cell contact-dependent protein exchange is explored as amechanism of intercellular signaling for the bacterium Myxococcus xanthus. A detailed biologically calibrated computational model is used to study how M. xanthusmore » optimizes the connection rate between cells and maximizes the spread of an extracellular protein within the population. The maximum rate of protein spreading is observed for cells that reverse direction optimally for swarming. Cells that reverse too slowly or too fast fail to spread extracellular protein efficiently. In particular, a specific range of cell reversal frequencies was observed to maximize the cell-cell connection rate and minimize the time of protein spreading. Furthermore, our findings suggest that predesigned motion reversal can be employed to enhance the collective behavior of biological synthetic active systems.« less
  • Crystals of the complex formed between the bacterial membrane protein OmpC and the antibacterial protein lactoferrin suitable for high-resolution structure determination have been obtained. The crystals belong to the hexagonal space group P6, with unit-cell parameters a = b = 116.3, c = 152.4 Å. Crystals of the complex formed between the outer membrane protein OmpC from Escherichia coli and the eukaryotic antibacterial protein lactoferrin from Camelus dromedarius (camel) have been obtained using a detergent environment. Initial data processing suggests that the crystals belong to the hexagonal space group P6, with unit-cell parameters a = b = 116.3, c =more » 152.4 Å, α = β = 90, γ = 120°. This indicated a Matthews coefficient (V{sub M}) of 3.3 Å{sup 3} Da{sup −1}, corresponding to a possible molecular complex involving four molecules of lactoferrin and two porin trimers in the unit cell (4832 amino acids; 533.8 kDa) with 63% solvent content. A complete set of diffraction data was collected to 3 Å resolution at 100 K. Structure determination by molecular replacement is in progress. Structural study of this first surface-exposed membrane-protein complex with an antibacterial protein will provide insights into the mechanism of action of OmpC as well as lactoferrin.« less
  • Application of in situ dynamic light scattering to solutions of protein–detergent complexes permits characterization of these complexes in samples as small as 2 µl in volume. Detergents are widely used for the isolation and solubilization of membrane proteins to support crystallization and structure determination. Detergents are amphiphilic molecules that form micelles once the characteristic critical micelle concentration (CMC) is achieved and can solubilize membrane proteins by the formation of micelles around them. The results are presented of a study of micelle formation observed by in situ dynamic light-scattering (DLS) analyses performed on selected detergent solutions using a newly designed advancedmore » hardware device. DLS was initially applied in situ to detergent samples with a total volume of approximately 2 µl. When measured with DLS, pure detergents show a monodisperse radial distribution in water at concentrations exceeding the CMC. A series of all-transn-alkyl-β-d-maltopyranosides, from n-hexyl to n-tetradecyl, were used in the investigations. The results obtained verify that the application of DLS in situ is capable of distinguishing differences in the hydrodynamic radii of micelles formed by detergents differing in length by only a single CH{sub 2} group in their aliphatic tails. Subsequently, DLS was applied to investigate the distribution of hydrodynamic radii of membrane proteins and selected water-insoluble proteins in presence of detergent micelles. The results confirm that stable protein–detergent complexes were prepared for (i) bacteriorhodopsin and (ii) FetA in complex with a ligand as examples of transmembrane proteins. A fusion of maltose-binding protein and the Duck hepatitis B virus X protein was added to this investigation as an example of a non-membrane-associated protein with low water solubility. The increased solubility of this protein in the presence of detergent could be monitored, as well as the progress of proteolytic cleavage to separate the fusion partners. This study demonstrates the potential of in situ DLS to optimize solutions of protein–detergent complexes for crystallization applications.« less