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2019 SRE Project

Biochemical pathways for aerotaxis in motile bacteria

Dr. Vasilios Alexiades, Mathematics, Univ. of Tennessee
Dr. Charles Collins , Mathematics, Univ. of Tennessee

Participants: Eniola Adewunmi (Mathematical Biology, Univ. of Tennessee); Ambrose Bechtel (BCMB, Univ. of Tennessee); Giovanni Colon Cabezudo (Mathematics, Univ. of Puerto Rico)

Bacteria photo. Project Description. Chemotaxis is the ability of motile bacteria to navigate chemical gradients to find conditions optimal for their metabolism and growth. When their flagella rotate counter-clockwise they swim straight, and when they rotate clockwise they tumble or reverse (move backward). Thus they execute a biased random walk, up the gradient of a chemoattractant or down the gradient of a chemorepellent, towards preferred locations. The flagellar motor is regulated by intricate biochemical signal transduction pathways. Receptors on the cell surface detect concentration gradients of chemoeffectors and via one or more pathways the signal is propagated to the flagellar motor. Aerotaxis is chemotaxis in an oxygen gradient. Aerotactic bacteria, such as Azospirillum brasilense, sense both very high and very low oxygen concentrations as repellents, while intermediate concentrations are attractants. The structure and connectivities of signaling pathways in A. brasilense is still unknown, and it is the subject of this project. We have developed ODE models of such pathways for chemotaxis and aerotaxis of the motile soil bacterium A. brasilense, which colonizes the roots of many plants and promotes their growth. This project will employ ODE models of signal transduction pathways from ligand to motor response to construct and compare plausible multiple pathways, with various connections among proteins, to discern which ones can reproduce experimental results on aerotactic response of wild type and of mutants.

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NIMBioS is supported by the National Science Foundation through NSF Award #DBI-1300426, with additional support from The University of Tennessee, Knoxville. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
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