Singly Flagellated <named-content content-type="genus-species">Pseudomonas aeruginosa</named-content> Chemotaxes Efficiently by Unbiased Motor Regulation

ABSTRACT Pseudomonas aeruginosa is an opportunistic human pathogen that has long been known to chemotax. More recently, it has been established that chemotaxis is an important factor in the ability of P. aeruginosa to make biofilms. Genes that allow P. aeruginosa to chemotax are homologous with gene...

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Autores principales:	Qiuxian Cai, Zhaojun Li, Qi Ouyang, Chunxiong Luo, Vernita D. Gordon
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2016
Materias:	Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/fe6005e7c30e4680a6a98b379cd7ca28
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spelling	oai:doaj.org-article:fe6005e7c30e4680a6a98b379cd7ca282021-11-15T15:41:41ZSingly Flagellated <named-content content-type="genus-species">Pseudomonas aeruginosa</named-content> Chemotaxes Efficiently by Unbiased Motor Regulation10.1128/mBio.00013-162150-7511https://doaj.org/article/fe6005e7c30e4680a6a98b379cd7ca282016-05-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00013-16https://doaj.org/toc/2150-7511ABSTRACT Pseudomonas aeruginosa is an opportunistic human pathogen that has long been known to chemotax. More recently, it has been established that chemotaxis is an important factor in the ability of P. aeruginosa to make biofilms. Genes that allow P. aeruginosa to chemotax are homologous with genes in the paradigmatic model organism for chemotaxis, Escherichia coli. However, P. aeruginosa is singly flagellated and E. coli has multiple flagella. Therefore, the regulation of counterclockwise/clockwise flagellar motor bias that allows E. coli to efficiently chemotax by runs and tumbles would lead to inefficient chemotaxis by P. aeruginosa, as half of a randomly oriented population would respond to a chemoattractant gradient in the wrong sense. How P. aeruginosa regulates flagellar rotation to achieve chemotaxis is not known. Here, we analyze the swimming trajectories of single cells in microfluidic channels and the rotations of cells tethered by their flagella to the surface of a variable-environment flow cell. We show that P. aeruginosa chemotaxes by symmetrically increasing the durations of both counterclockwise and clockwise flagellar rotations when swimming up the chemoattractant gradient and symmetrically decreasing rotation durations when swimming down the chemoattractant gradient. Unlike the case for E. coli, the counterclockwise/clockwise bias stays constant for P. aeruginosa. We describe P. aeruginosa’s chemotaxis using an analytical model for symmetric motor regulation. We use this model to do simulations that show that, given P. aeruginosa’s physiological constraints on motility, its distinct, symmetric regulation of motor switching optimizes chemotaxis. IMPORTANCE Chemotaxis has long been known to strongly affect biofilm formation by the opportunistic human pathogen P. aeruginosa, whose essential chemotaxis genes have homologues in E. coli, which achieves chemotaxis by biasing the relative probability of counterclockwise and clockwise flagellar rotation. However, the physiological difference between multiflagellated E. coli and singly flagellated P. aeruginosa implies that biased motor regulation should prevent P. aeruginosa populations from chemotaxing efficiently. Here, we used experiments, analytical modeling, and simulations to demonstrate that P. aeruginosa uses unbiased, symmetric regulation of the flagellar motor to maximize its chemotaxis efficiency. This mode of chemotaxis was not previously known and demonstrates a new variant of a paradigmatic signaling system in an important human pathogen.Qiuxian CaiZhaojun LiQi OuyangChunxiong LuoVernita D. GordonAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 7, Iss 2 (2016)
institution	DOAJ
collection	DOAJ
language	EN
topic	Microbiology QR1-502
spellingShingle	Microbiology QR1-502 Qiuxian Cai Zhaojun Li Qi Ouyang Chunxiong Luo Vernita D. Gordon Singly Flagellated <named-content content-type="genus-species">Pseudomonas aeruginosa</named-content> Chemotaxes Efficiently by Unbiased Motor Regulation
description	ABSTRACT Pseudomonas aeruginosa is an opportunistic human pathogen that has long been known to chemotax. More recently, it has been established that chemotaxis is an important factor in the ability of P. aeruginosa to make biofilms. Genes that allow P. aeruginosa to chemotax are homologous with genes in the paradigmatic model organism for chemotaxis, Escherichia coli. However, P. aeruginosa is singly flagellated and E. coli has multiple flagella. Therefore, the regulation of counterclockwise/clockwise flagellar motor bias that allows E. coli to efficiently chemotax by runs and tumbles would lead to inefficient chemotaxis by P. aeruginosa, as half of a randomly oriented population would respond to a chemoattractant gradient in the wrong sense. How P. aeruginosa regulates flagellar rotation to achieve chemotaxis is not known. Here, we analyze the swimming trajectories of single cells in microfluidic channels and the rotations of cells tethered by their flagella to the surface of a variable-environment flow cell. We show that P. aeruginosa chemotaxes by symmetrically increasing the durations of both counterclockwise and clockwise flagellar rotations when swimming up the chemoattractant gradient and symmetrically decreasing rotation durations when swimming down the chemoattractant gradient. Unlike the case for E. coli, the counterclockwise/clockwise bias stays constant for P. aeruginosa. We describe P. aeruginosa’s chemotaxis using an analytical model for symmetric motor regulation. We use this model to do simulations that show that, given P. aeruginosa’s physiological constraints on motility, its distinct, symmetric regulation of motor switching optimizes chemotaxis. IMPORTANCE Chemotaxis has long been known to strongly affect biofilm formation by the opportunistic human pathogen P. aeruginosa, whose essential chemotaxis genes have homologues in E. coli, which achieves chemotaxis by biasing the relative probability of counterclockwise and clockwise flagellar rotation. However, the physiological difference between multiflagellated E. coli and singly flagellated P. aeruginosa implies that biased motor regulation should prevent P. aeruginosa populations from chemotaxing efficiently. Here, we used experiments, analytical modeling, and simulations to demonstrate that P. aeruginosa uses unbiased, symmetric regulation of the flagellar motor to maximize its chemotaxis efficiency. This mode of chemotaxis was not previously known and demonstrates a new variant of a paradigmatic signaling system in an important human pathogen.
format	article
author	Qiuxian Cai Zhaojun Li Qi Ouyang Chunxiong Luo Vernita D. Gordon
author_facet	Qiuxian Cai Zhaojun Li Qi Ouyang Chunxiong Luo Vernita D. Gordon
author_sort	Qiuxian Cai
title	Singly Flagellated <named-content content-type="genus-species">Pseudomonas aeruginosa</named-content> Chemotaxes Efficiently by Unbiased Motor Regulation
title_short	Singly Flagellated <named-content content-type="genus-species">Pseudomonas aeruginosa</named-content> Chemotaxes Efficiently by Unbiased Motor Regulation
title_full	Singly Flagellated <named-content content-type="genus-species">Pseudomonas aeruginosa</named-content> Chemotaxes Efficiently by Unbiased Motor Regulation
title_fullStr	Singly Flagellated <named-content content-type="genus-species">Pseudomonas aeruginosa</named-content> Chemotaxes Efficiently by Unbiased Motor Regulation
title_full_unstemmed	Singly Flagellated <named-content content-type="genus-species">Pseudomonas aeruginosa</named-content> Chemotaxes Efficiently by Unbiased Motor Regulation
title_sort	singly flagellated <named-content content-type="genus-species">pseudomonas aeruginosa</named-content> chemotaxes efficiently by unbiased motor regulation
publisher	American Society for Microbiology
publishDate	2016
url	https://doaj.org/article/fe6005e7c30e4680a6a98b379cd7ca28
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Singly Flagellated <named-content content-type="genus-species">Pseudomonas aeruginosa</named-content> Chemotaxes Efficiently by Unbiased Motor Regulation

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