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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

Schematic showing the acquisition and derivation of stator genes through bacterial evolution.First, the ancestral bacteria acquired the Na+-driven stator, and earliest branched bacteria have the Na+-driven stator. The stator then was converted into the H+-driven type through the middle period of bacterial evolution. The Na+-driven stator of the late-branched bacteria seems to be provided from early-branched bacteria (Aquificae or Thermotogae) by lateral gene transfer.
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f6: Schematic showing the acquisition and derivation of stator genes through bacterial evolution.First, the ancestral bacteria acquired the Na+-driven stator, and earliest branched bacteria have the Na+-driven stator. The stator then was converted into the H+-driven type through the middle period of bacterial evolution. The Na+-driven stator of the late-branched bacteria seems to be provided from early-branched bacteria (Aquificae or Thermotogae) by lateral gene transfer.

Mentions: The fact that MotA in the flagellar motor of E. coli is replaceable with MotA of A. aeolicus indicates that the interaction surface of the stator and rotor is highly conserved not only among phylogenetically close species such as E. coli, V. alginolyticus and R. sphaeroides as previously reported3031, but also between phylogenetically distant species. This may correlate with the high similarity among the crystal structures of FliG, a rotor component that directly interacts with MotA via electrostatic interaction, from T. maritima, Helicobacter pylori and A. aeolicus383940. We also showed that chimeric E. coli FliG, whose C-terminal domain where directly interact with MotA is replaced with A. aeolicus FliG, is compatible with native FliG in E. coli (Fig. S5), supporting the conservation of the mechanism for the motor function among bacteria. The phylogenetic analysis of motA and motB genes from various bacteria suggests high sequence similarities among motA/motB (or their orthologous) genes of A. aeolicus, T. maritima, Vibrio species and B. subtilis, which mostly encode Na+-driven stators (Fig. S6). Currently, there are two alternative hypothetical scenarios for the evolution of Aquificae; i) Aquificae branched at an early stage in the evolutionary lineage of bacteria45, and ii) Aquificae belong to a group near the ε-proteobacteria and some genes, including ribosomal genes, are derived from other species by lateral gene transfer641. Whichever scenario is correct, the flagellar genes of A. aeolicus are thought to be among the most primordial flagellar genes, because of the sequence similarities with those of T. maritima, which is also thought to be an early-branched bacterium. These lines of evidence suggest that the earliest stator of the flagellar motor is a Na+-driven type stator. Through the evolution of bacteria, the function of the stator might have been converted into the H+-driven type, and the Na+-driven type stator might have been re-acquired in some late-branching bacteria by lateral gene transfer from Aquificae in some specific species (Fig. 6). The low sequence similarity between the two types of stators in a single species (e.g. MotA/B (H+ type) and PomA/B (Na+ type) in Vibrio or Shewanella, or MotA/B (H+ type) and MotP/S (Na+ type) in Bacillus) also supports the occurrence of lateral gene transfer of the Na+-driven stator.


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)

Schematic showing the acquisition and derivation of stator genes through bacterial evolution.First, the ancestral bacteria acquired the Na+-driven stator, and earliest branched bacteria have the Na+-driven stator. The stator then was converted into the H+-driven type through the middle period of bacterial evolution. The Na+-driven stator of the late-branched bacteria seems to be provided from early-branched bacteria (Aquificae or Thermotogae) by lateral gene transfer.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f6: Schematic showing the acquisition and derivation of stator genes through bacterial evolution.First, the ancestral bacteria acquired the Na+-driven stator, and earliest branched bacteria have the Na+-driven stator. The stator then was converted into the H+-driven type through the middle period of bacterial evolution. The Na+-driven stator of the late-branched bacteria seems to be provided from early-branched bacteria (Aquificae or Thermotogae) by lateral gene transfer.
Mentions: The fact that MotA in the flagellar motor of E. coli is replaceable with MotA of A. aeolicus indicates that the interaction surface of the stator and rotor is highly conserved not only among phylogenetically close species such as E. coli, V. alginolyticus and R. sphaeroides as previously reported3031, but also between phylogenetically distant species. This may correlate with the high similarity among the crystal structures of FliG, a rotor component that directly interacts with MotA via electrostatic interaction, from T. maritima, Helicobacter pylori and A. aeolicus383940. We also showed that chimeric E. coli FliG, whose C-terminal domain where directly interact with MotA is replaced with A. aeolicus FliG, is compatible with native FliG in E. coli (Fig. S5), supporting the conservation of the mechanism for the motor function among bacteria. The phylogenetic analysis of motA and motB genes from various bacteria suggests high sequence similarities among motA/motB (or their orthologous) genes of A. aeolicus, T. maritima, Vibrio species and B. subtilis, which mostly encode Na+-driven stators (Fig. S6). Currently, there are two alternative hypothetical scenarios for the evolution of Aquificae; i) Aquificae branched at an early stage in the evolutionary lineage of bacteria45, and ii) Aquificae belong to a group near the ε-proteobacteria and some genes, including ribosomal genes, are derived from other species by lateral gene transfer641. Whichever scenario is correct, the flagellar genes of A. aeolicus are thought to be among the most primordial flagellar genes, because of the sequence similarities with those of T. maritima, which is also thought to be an early-branched bacterium. These lines of evidence suggest that the earliest stator of the flagellar motor is a Na+-driven type stator. Through the evolution of bacteria, the function of the stator might have been converted into the H+-driven type, and the Na+-driven type stator might have been re-acquired in some late-branching bacteria by lateral gene transfer from Aquificae in some specific species (Fig. 6). The low sequence similarity between the two types of stators in a single species (e.g. MotA/B (H+ type) and PomA/B (Na+ type) in Vibrio or Shewanella, or MotA/B (H+ type) and MotP/S (Na+ type) in Bacillus) also supports the occurrence of lateral gene transfer of the Na+-driven stator.

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