ArcS, the Cognate Sensor Kinase in an Atypical Arc System of
            <i>Shewanella oneidensis</i>
            MR-1

Lassak, Jürgen; Henche, Anna-Lena; Binnenkade, Lucas; Thormann, Kai M.

doi:10.1128/aem.00512-10

Cited by 128 publications

(135 citation statements)

References 78 publications

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“…Bacterial strains and plasmids are summarized in Tables S1 and S2. Construction of plasmids and genetically modified strains of S. putrefaciens CN-32 was essentially carried out as previously described (44,45). Detailed information on strain construction, growth conditions, and media is provided in SI Materials and Methods.…”

Section: Methodsmentioning

confidence: 99%

Bacteria exploit a polymorphic instability of the flagellar filament to escape from traps

Kühn

Schmidt

Eckhardt

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Many bacterial species swim by rotating single polar helical flagella. Depending on the direction of rotation, they can swim forward or backward and change directions to move along chemical gradients but also to navigate their obstructed natural environment in soils, sediments, or mucus. When they get stuck, they naturally try to back out, but they can also resort to a radically different flagellar mode, which we discovered here. Using high-speed microscopy, we monitored the swimming behavior of the monopolarly flagellated species Shewanella putrefaciens with fluorescently labeled flagellar filaments at an agarose-glass interface. We show that, when a cell gets stuck, the polar flagellar filament executes a polymorphic change into a spiral-like form that wraps around the cell body in a spiral-like fashion and enables the cell to escape by a screw-like backward motion. Microscopy and modeling suggest that this propagation mode is triggered by an instability of the flagellum under reversal of the rotation and the applied torque. The switch is reversible and bacteria that have escaped the trap can return to their normal swimming mode by another reversal of motor direction. The screw-type flagellar arrangement enables a unique mode of propagation and, given the large number of polarly flagellated bacteria, we expect it to be a common and widespread escape or motility mode in complex and structured environments.Shewanella | flagella | motility | structured environment

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Section: Methodsmentioning

confidence: 99%

Bacteria exploit a polymorphic instability of the flagellar filament to escape from traps

Kühn

Schmidt

Eckhardt

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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124

130

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“…After PCR product purification, the fragments were fused by overlap PCR (37). The overlap product was isolated from an agarose gel, digested with the corresponding restriction enzymes, and ligated into the suicide vector pNPTS138-R6KT (34). The resulting plasmid was introduced into V. harveyi by conjugative mating using E. coli WM3064 as the donor in LB medium containing DAP.…”

Section: Methodsmentioning

confidence: 99%

“…In-frame deletion mutants of V. harveyi BAA-1116 were constructed as previously described, leaving terminal sections of the target genes (34)(35)(36). For this purpose, upstream and downstream fragments (ranging from 500 to 1,000 bp) of the desired gene regions were amplified by using the corresponding primers (see Table S2 in the supplemental material).…”

Section: Methodsmentioning

confidence: 99%

The Phosphorylation Flow of the Vibrio harveyi Quorum-Sensing Cascade Determines Levels of Phenotypic Heterogeneity in the Population

et al. 2015

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Quorum sensing (QS) is a communication process that enables a bacterial population to coordinate and synchronize specific behaviors. The bioluminescent marine bacterium Vibrio harveyi integrates three autoinducer (AI) signals into one quorumsensing cascade comprising a phosphorelay involving three hybrid sensor kinases: LuxU; LuxO, an Hfq/small RNA (sRNA) switch; and the transcriptional regulator LuxR. Using a new set of V. harveyi mutants lacking genes for the AI synthases and/or sensors, we assayed the activity of the quorum-sensing cascade at the population and single-cell levels, with a specific focus on signal integration and noise levels. We found that the ratios of kinase activities to phosphatase activities of the three sensors and, hence, the extent of phosphorylation of LuxU/LuxO are important not only for the signaling output but also for the degree of noise in the system. The pools of phosphorylated LuxU/LuxO per cell directly determine the amounts of sRNAs produced and, consequently, the copy number of LuxR, generating heterogeneous quorum-sensing activation at the single-cell level. We conclude that the ability to drive the heterogeneous expression of QS-regulated genes in V. harveyi is an inherent feature of the architecture of the QS cascade. IMPORTANCEV. harveyi possesses one of the most complex quorum-sensing (QS) cascades known, using three different autoinducers (AIs) to control the induction of, e.g., bioluminescence, virulence factors, and biofilm and exoprotease production. We constructed various V. harveyi mutants to study the impact of each component and subsystem of the QS signaling cascade on QS activation at the population and single-cell levels. We found that the output was homogeneous only in the presence of all AIs. In the absence of any one AI, QS activation varied from cell to cell, resulting in phenotypic heterogeneity. This study elucidates a molecular design principle which enables a tightly integrated signaling cascade to control the expression of diverse phenotypes within a genetically homogeneous population. Q uorum sensing (QS) is a cell-to-cell communication process which relies on small diffusible molecules called autoinducers (AIs). This phenomenon was first described for luminescent bacteria such as the symbiotic marine bacterium Vibrio fischeri (1-3). Since then, many different QS systems have been discovered in Gram-negative as well as Gram-positive bacteria (4). AIs are synthesized and released into the environment, therefore accumulating in a cell-number-dependent manner. AIs are perceived by specific sensors. Once the AI concentration reaches a certain threshold, QS is triggered, and cells produce a phenotypic answer by activating genes for traits such as virulence, biofilm formation, luminescence, antibiotic production, or conjugation that benefit the population as a whole (5).Vibrio harveyi strain BAA-1116 (recently reclassified as Vibrio campbellii [6]) uses a complex QS cascade and responds to three different classes of AIs: HAI-1, an acyl homoserine l...

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“…Markerless in-frame deletion mutants of S. oneidensis were constructed as reported previously by using the suicide vector pNPTS138-R6KT (35); the appropriate PCR fragments were generated using the primers listed in Table S1 in the supplemental material. Successful deletion was confirmed by PCR using primers bracketing the deleted region.…”

Section: Methodsmentioning

confidence: 99%

Functional Specificity of Extracellular Nucleases of Shewanella oneidensis MR-1

Heun

Binnenkade

Kreienbaum

et al. 2012

Appl Environ Microbiol

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ABSTRACTBacterial species such asShewanella oneidensisMR-1 require extracellular nucleolytic activity for the utilization of extracellular DNA (eDNA) as a source of nutrients and for the turnover of eDNA as a structural matrix component during biofilm formation. We have previously characterized two extracellular nucleases ofS. oneidensisMR-1, ExeM and ExeS. Although both are involved in biofilm formation, they are not specifically required for the utilization of eDNA as a nutrient. Here we identified and characterized EndA, a third extracellular nuclease ofShewanella. The heterologously overproduced and purified protein was highly active and rapidly degraded linear and supercoiled DNAs of various origins. Divalent metal ions (Mg2+or Mn2+) were required for function.endAis cotranscribed withphoA, an extracellular phosphatase, and is not upregulated upon phosphostarvation. Deletion ofendAabolished both extracellular degradation of DNA byS. oneidensisMR-1 and the ability to use eDNA as a sole source of phosphorus. PhoA is not strictly required for the exploitation of eDNA as a nutrient. The activity of EndA prevents the formation of large cell aggregates during planktonic growth. However, in contrast to the findings for ExeM,endAdeletion had only minor effects on biofilm formation. The findings strongly suggest that the extracellular nucleases ofS. oneidensisexert specific functions required under different conditions.

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ArcS, the Cognate Sensor Kinase in an Atypical Arc System of Shewanella oneidensis MR-1

Cited by 128 publications

References 78 publications

Bacteria exploit a polymorphic instability of the flagellar filament to escape from traps

Bacteria exploit a polymorphic instability of the flagellar filament to escape from traps

The Phosphorylation Flow of the Vibrio harveyi Quorum-Sensing Cascade Determines Levels of Phenotypic Heterogeneity in the Population

Functional Specificity of Extracellular Nucleases of Shewanella oneidensis MR-1

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