scholarly journals The Polar Flagellar Motor of Vibrio cholerae Is Driven by an Na+ Motive Force

1999 ◽  
Vol 181 (6) ◽  
pp. 1927-1930 ◽  
Author(s):  
Seiji Kojima ◽  
Koichiro Yamamoto ◽  
Ikuro Kawagishi ◽  
Michio Homma
Keyword(s):  
Energy Source ◽  
Vibrio Cholerae ◽  
Specific Inhibitor ◽  
Motive Force ◽  
Flagellar Motor ◽  
Genome Sequencing Project ◽  
Genome Database ◽  
Sequencing Project ◽  
Organelle Motility ◽  
Motile Bacterium

ABSTRACT Vibrio cholerae is a highly motile bacterium which possesses a single polar flagellum as a locomotion organelle. Motility is thought to be an important factor for the virulence ofV. cholerae. The genome sequencing project of this organism is in progress, and the genes that are highly homologous to the essential genes of the Na+-driven polar flagellar motor of Vibrio alginolyticus were found in the genome database of V. cholerae. The energy source of its flagellar motor was investigated. We examined the Na+ dependence and the sensitivity to the Na+ motor-specific inhibitor of the motility of the V. cholerae strains and present the evidence that the polar flagellar motor of V. choleraeis driven by an Na+ motive force.

scholarly journals Genetic Analysis of Vibrio cholerae Monolayer Formation Reveals a Key Role for ΔΨ in the Transition to Permanent Attachment

2008 ◽  
Vol 190 (24) ◽  
pp. 8185-8196 ◽  
Author(s):  
Katrina L. Van Dellen ◽  
Laetitia Houot ◽  
Paula I. Watnick
Keyword(s):  
Membrane Potential ◽  
Vibrio Cholerae ◽  
Bacterial Cell ◽  
Large Scale ◽  
Genetic Screen ◽  
Motive Force ◽  
Flagellar Motor ◽  
Flagellar Motility ◽  
Monolayer Formation ◽  
Bacterial Cell Membrane

ABSTRACT A bacterial monolayer biofilm is a collection of cells attached to a surface but not to each other. Monolayer formation is initiated when a bacterial cell forms a transient attachment to a surface. While some transient attachments are broken, others transition into the permanent attachments that define a monolayer biofilm. In this work, we describe the results of a large-scale, microscopy-based genetic screen for Vibrio cholerae mutants that are defective in formation of a monolayer biofilm. This screen identified mutations that alter both transient and permanent attachment. Transient attachment was somewhat slower in the absence of flagellar motility. However, flagellar mutants eventually formed a robust monolayer. In contrast, in the absence of the flagellar motor, monolayer formation was severely impaired. A number of proteins that modulate the V. cholerae ion motive force were also found to affect the transition from transient to permanent attachment. Using chemicals that dissipate various components of the ion motive force, we discovered that dissipation of the membrane potential (ΔΨ) completely blocks the transition from transient to permanent attachment. We propose that as a bacterium approaches a surface, the interaction of the flagellum with the surface leads to transient hyperpolarization of the bacterial cell membrane. This, in turn, initiates the transition to permanent attachment.

scholarly journals Only One of the Five CheY Homologs in Vibrio cholerae Directly Switches Flagellar Rotation

2005 ◽  
Vol 187 (24) ◽  
pp. 8403-8410 ◽  
Author(s):  
Akihiro Hyakutake ◽  
Michio Homma ◽  
Melissa J. Austin ◽  
Markus A. Boin ◽  
Claudia C. Häse ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Gene Clusters ◽  
Swimming Behavior ◽  
Phosphoryl Group ◽  
Flagellar Motor ◽  
Response Regulators ◽  
E Coli ◽  
Control Functions ◽  
Flagellar Rotation ◽  
Principal Roles

ABSTRACT Vibrio cholerae has three sets of chemotaxis (Che) proteins, including three histidine kinases (CheA) and four response regulators (CheY) that are encoded by three che gene clusters. We deleted the cheY genes individually or in combination and found that only the cheY3 deletion impaired chemotaxis, reinforcing the previous conclusion that che cluster II is involved in chemotaxis. However, this does not exclude the involvement of the other clusters in chemotaxis. In other bacteria, phospho-CheY binds directly to the flagellar motor to modulate its rotation, and CheY overexpression, even without CheA, causes extremely biased swimming behavior. We reasoned that a V. cholerae CheY homolog, if it directly controls flagellar rotation, should also induce extreme swimming behavior when overproduced. This was the case for CheY3 (che cluster II). However, no other CheY homolog, including the putative CheY (CheY0) protein encoded outside the che clusters, affected swimming, demonstrating that these CheY homologs cannot act directly on the flagellar motor. CheY4 very slightly enhanced the spreading of an Escherichia coli cheZ mutant in semisolid agar, raising the possibility that it can affect chemotaxis by removing a phosphoryl group from CheY3. We also found that V. cholerae CheY3 and E. coli CheY are only partially exchangeable. Mutagenic analyses suggested that this may come from coevolution of the interacting pair of proteins, CheY and the motor protein FliM. Taken together, it is likely that the principal roles of che clusters I and III as well as cheY0 are to control functions other than chemotaxis.

scholarly journals Effect of the MotA(M206I) Mutation on Torque Generation and Stator Assembly in theSalmonellaH+-Driven Flagellar Motor

2019 ◽  
Vol 201 (6) ◽  
Author(s):  
Yuya Suzuki ◽  
Yusuke V. Morimoto ◽  
Kodai Oono ◽  
Fumio Hayashi ◽  
Kenji Oosawa ◽  
...  
Keyword(s):  
Ion Flux ◽  
Motive Force ◽  
Flagellar Motor ◽  
Wild Type ◽  
Torque Generation ◽  
Unit Speed ◽  
Bacterial Flagellar Motor ◽  
Ph Dependent ◽  
Type Motor ◽  
External Ph

ABSTRACTThe bacterial flagellar motor is composed of a rotor and a dozen stators and converts the ion flux through the stator into torque. Each stator unit alternates in its attachment to and detachment from the rotor even during rotation. In some species, stator assembly depends on the input energy, but it remains unclear how an electrochemical potential across the membrane (e.g., proton motive force [PMF]) or ion flux is involved in stator assembly dynamics. Here, we focused on pH dependence of a slow motile MotA(M206I) mutant ofSalmonella. The MotA(M206I) motor produces torque comparable to that of the wild-type motor near stall, but its rotation rate is considerably decreased as the external load is reduced. Rotation assays of flagella labeled with 1-μm beads showed that the rotation rate of the MotA(M206I) motor is increased by lowering the external pH whereas that of the wild-type motor is not. Measurements of the speed produced by a single stator unit using 1-μm beads showed that the unit speed of the MotA(M206I) is about 60% of that of the wild-type and that a decrease in external pH did not affect the MotA(M206I) unit speed. Analysis of the subcellular stator localization revealed that the number of functional stators is restored by lowering the external pH. The pH-dependent improvement of stator assembly was observed even when the PMF was collapsed and proton transfer was inhibited. These results suggest that MotA-Met206 is responsible for not only load-dependent energy coupling between the proton influx and rotation but also pH-dependent stator assembly.IMPORTANCEThe bacterial flagellar motor is a rotary nanomachine driven by the electrochemical transmembrane potential (ion motive force). About 10 stators (MotA/MotB complexes) are docked around a rotor, and the stator recruitment depends on the load, ion motive force, and coupling ion flux. The MotA(M206I) mutation slows motor rotation and decreases the number of docked stators inSalmonella. We show that lowering the external pH improves the assembly of the mutant stators. Neither the collapse of the ion motive force nor a mutation mimicking the proton-binding state inhibited stator localization to the motor. These results suggest that MotA-Met206 is involved in torque generation and proton translocation and that stator assembly is stabilized by protonation of the stator.

scholarly journals PAK Paradox: Paramecium Appears To Have More K+-Channel Genes than Humans

2003 ◽  
Vol 2 (4) ◽  
pp. 737-745 ◽  
Author(s):  
W. John Haynes ◽  
Kit-Yin Ling ◽  
Yoshiro Saimi ◽  
Ching Kung
Keyword(s):  
Reverse Transcription ◽  
Essential Role ◽  
K Channel ◽  
Genome Sequencing Project ◽  
Freshwater Environment ◽  
Sequencing Project ◽  
Channel Gene ◽  
The Past ◽  
Reverse Transcription Pcr ◽  
Pcr Products

ABSTRACT K+-selective ion channels (K+ channels) have been found in bacteria, archaea, eucarya, and viruses. In Paramecium and other ciliates, K+ currents play an essential role in cilia-based motility. We have retrieved and sequenced seven closely related Paramecium K+-channel gene (PAK) sequences by using previously reported fragments. An additional eight unique K+-channel sequences were retrieved from an indexed library recently used in a pilot genome sequencing project. Alignments of these protein translations indicate that while these 15 genes have diverged at different times, they all maintain many characteristics associated with just one subclass of metazoan K+ channels (CNG/ERG type). Our results indicate that most of the genes are expressed, because all predicted frameshifts and several gaps in the homolog alignments contain Paramecium intron sequences deleted from reverse transcription-PCR products. Some of the variations in the 15 genomic nucleotide sequences involve an absence of introns, even between very closely related sequences, suggesting a potential occurrence of reverse transcription in the past. Extrapolation from the available genome sequence indicates that Paramecium harbors as many as several hundred of this one type of K+-channel gene. This quantity is far more numerous than those of K+-channel genes of all types known in any metazoan (e.g., ∼80 in humans, ∼30 in flies, and ∼15 in Arabidopsis). In an effort to understand this plurality, we discuss several possible reasons for their maintenance, including variations in expression levels in response to changes in the freshwater environment, like that seen with other major plasma membrane proteins in Paramecium.

The NIAID Influenza Genome Sequencing Project

2008 ◽  
pp. 109-113 ◽  
Author(s):  
Lone Simonsen ◽  
Gayle Bernabe ◽  
Karen Lacourciere ◽  
Robert J. Taylor ◽  
Maria Y. Giovanni
Keyword(s):  
Genome Sequencing ◽  
Genome Sequencing Project ◽  
Sequencing Project
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