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Sodium-driven energy conversion for flagellar rotation of the earliest divergent hyperthermophilic bacterium.

Takekawa N, Nishiyama M, Kaneseki T, Kanai T, Atomi H, Kojima S, Homma M - Sci Rep (2015)

Bottom Line: Here we observed that A. aeolicus has polar flagellum and can swim with a speed of 90 μm s(-1) at 85 °C.We expressed the A. aeolicus mot genes (motA and motB), which encode the torque generating stator proteins of the flagellar motor, in a corresponding mot nonmotile mutant of Escherichia coli.Using this system in E. coli, we demonstrate that the A. aeolicus motor is driven by Na(+).

View Article: PubMed Central - PubMed

Affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.

ABSTRACT
Aquifex aeolicus is a hyperthermophilic, hydrogen-oxidizing and carbon-fixing bacterium that can grow at temperatures up to 95 °C. A. aeolicus has an almost complete set of flagellar genes that are conserved in bacteria. Here we observed that A. aeolicus has polar flagellum and can swim with a speed of 90 μm s(-1) at 85 °C. We expressed the A. aeolicus mot genes (motA and motB), which encode the torque generating stator proteins of the flagellar motor, in a corresponding mot nonmotile mutant of Escherichia coli. Its motility was slightly recovered by expression of A. aeolicus MotA and chimeric MotB whose periplasmic region was replaced with that of E. coli. A point mutation in the A. aeolicus MotA cytoplasmic region remarkably enhanced the motility. Using this system in E. coli, we demonstrate that the A. aeolicus motor is driven by Na(+). As motor proteins from hyperthermophilic bacteria represent the earliest motor proteins in evolution, this study strongly suggests that ancient bacteria used Na(+) for energy coupling of the flagellar motor. The Na(+)-driven flagellar genes might have been laterally transferred from early-branched bacteria into late-branched bacteria and the interaction surfaces of the stator and rotor seem not to change in evolution.

No MeSH data available.


Related in: MedlinePlus

Transmission electron micrograph of the cells of A. aeolicus.(A) Image of the whole cell and its flagellum. (B) and (C) Partial enlargements of the flagellated cell pole. Cells were negatively stained with 1% uranyl acetate.
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f2: Transmission electron micrograph of the cells of A. aeolicus.(A) Image of the whole cell and its flagellum. (B) and (C) Partial enlargements of the flagellated cell pole. Cells were negatively stained with 1% uranyl acetate.

Mentions: A. aeolicus has almost all of the flagellar genes conserved in Gram-negative bacteria (Fig. S1). However, there has been no report showing whether A. aeolicus actually has flagella. To examine this point, we cultivated the wild-type A. aeolicus VF5 strain in inorganic medium under a H2/CO2/O2 gas atmosphere at its optimum growth temperature of 85 °C, and the cultivated cells were observed by transmission electron microscope (TEM) using negative staining. The cells were rod-shaped and flagellar filaments existed at the pole of some cells (Fig. 2A,B), although most of the cells did not have flagella. The most of flagellated cells have a single polar flagellum, while few cells harbored multiple flagella at their cell pole (Fig. 2C).


Sodium-driven energy conversion for flagellar rotation of the earliest divergent hyperthermophilic bacterium.

Takekawa N, Nishiyama M, Kaneseki T, Kanai T, Atomi H, Kojima S, Homma M - Sci Rep (2015)

Transmission electron micrograph of the cells of A. aeolicus.(A) Image of the whole cell and its flagellum. (B) and (C) Partial enlargements of the flagellated cell pole. Cells were negatively stained with 1% uranyl acetate.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525482&req=5

f2: Transmission electron micrograph of the cells of A. aeolicus.(A) Image of the whole cell and its flagellum. (B) and (C) Partial enlargements of the flagellated cell pole. Cells were negatively stained with 1% uranyl acetate.
Mentions: A. aeolicus has almost all of the flagellar genes conserved in Gram-negative bacteria (Fig. S1). However, there has been no report showing whether A. aeolicus actually has flagella. To examine this point, we cultivated the wild-type A. aeolicus VF5 strain in inorganic medium under a H2/CO2/O2 gas atmosphere at its optimum growth temperature of 85 °C, and the cultivated cells were observed by transmission electron microscope (TEM) using negative staining. The cells were rod-shaped and flagellar filaments existed at the pole of some cells (Fig. 2A,B), although most of the cells did not have flagella. The most of flagellated cells have a single polar flagellum, while few cells harbored multiple flagella at their cell pole (Fig. 2C).

Bottom Line: Here we observed that A. aeolicus has polar flagellum and can swim with a speed of 90 μm s(-1) at 85 °C.We expressed the A. aeolicus mot genes (motA and motB), which encode the torque generating stator proteins of the flagellar motor, in a corresponding mot nonmotile mutant of Escherichia coli.Using this system in E. coli, we demonstrate that the A. aeolicus motor is driven by Na(+).

View Article: PubMed Central - PubMed

Affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.

ABSTRACT
Aquifex aeolicus is a hyperthermophilic, hydrogen-oxidizing and carbon-fixing bacterium that can grow at temperatures up to 95 °C. A. aeolicus has an almost complete set of flagellar genes that are conserved in bacteria. Here we observed that A. aeolicus has polar flagellum and can swim with a speed of 90 μm s(-1) at 85 °C. We expressed the A. aeolicus mot genes (motA and motB), which encode the torque generating stator proteins of the flagellar motor, in a corresponding mot nonmotile mutant of Escherichia coli. Its motility was slightly recovered by expression of A. aeolicus MotA and chimeric MotB whose periplasmic region was replaced with that of E. coli. A point mutation in the A. aeolicus MotA cytoplasmic region remarkably enhanced the motility. Using this system in E. coli, we demonstrate that the A. aeolicus motor is driven by Na(+). As motor proteins from hyperthermophilic bacteria represent the earliest motor proteins in evolution, this study strongly suggests that ancient bacteria used Na(+) for energy coupling of the flagellar motor. The Na(+)-driven flagellar genes might have been laterally transferred from early-branched bacteria into late-branched bacteria and the interaction surfaces of the stator and rotor seem not to change in evolution.

No MeSH data available.


Related in: MedlinePlus