Faculty Profiles - KOJIMA, Seiji

Papers - KOJIMA, Seiji

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Molecular architecture of the sheathed polar flagellum in Vibrio alginolyticus Reviewed

Shiwei Zhu, Tatsuro Nishikino, Bo Hu, Seiji Kojima, Michio Homma, Jun Liu

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Vol. 114 ( 41 ) page： 10966 - 10971 2017.10

Language：English Publishing type：Research paper (scientific journal) Publisher：NATL ACAD SCIENCES

Vibrio species are Gram-negative rod-shaped bacteria that are ubiquitous and often highly motile in aqueous environments. Vibrio swimming motility is driven by a polar flagellum covered with a membranous sheath, but this sheathed flagellum is not well understood at the molecular level because of limited structural information. Here, we use Vibrio alginolyticus as a model system to study the sheathed flagellum in intact cells by combining cryoelectron tomography (cryo-ET) and subtomogram analysis with a genetic approach. We reveal striking differences between sheathed and unsheathed flagella in V. alginolyticus cells, including a novel ring-like structure at the bottom of the hook that is associated with major remodeling of the outer membrane and sheath formation. Using mutants defective in flagellar motor components, we defined a Vibrio-specific feature (also known as the T ring) as a distinctive periplasmic structure with 13-fold symmetry. The unique architecture of the T ring provides a static platform to recruit the PomA/B complexes, which are required to generate higher torques for rotation of the sheathed flagellum and fast motility of Vibrio cells. Furthermore, the Vibrio flagellar motor exhibits an intrinsic length variation between the inner and the outer membrane bound complexes, suggesting the outer membrane bound complex can shift slightly along the axial rod during flagellar rotation. Together, our detailed analyses of the polar flagella in intact cells provide insights into unique aspects of the sheathed flagellum and the distinct motility of Vibrio species.

DOI： 10.1073/pnas.1712489114

Localization and domain characterization of the SflA regulator of flagellar formation in Vibrio alginolyticus Reviewed

Satoshi Inaba, Takehiko Nishigaki, Norihiro Takekawa, Seiji Kojima, Michio Homma

GENES TO CELLS Vol. 22 ( 7 ) page： 619 - 627 2017.7

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY

Many swimming bacteria use flagella as locomotive organelles. The spatial and numerical regulation of flagellar biosynthesis differs by bacterial species. The marine bacteria Vibrio alginolyticus use a single polar flagellum whose number is regulated positively by FlhF and negatively by FlhG. Cells lacking FlhF and FlhG have no flagellum. The motility defect in an flhFG deletion was suppressed by a mutation in the sflA gene that resulted in the production of multiple, peritrichous flagella. SflA is a Vibrio-specific protein. SlfA either facilitates flagellum growth at the cell pole or prevents flagellar formation on the cell body by an unknown mechanism. Fluorescent protein fusions to SflA localized to the cell pole in the presence of FlhF and FlhG, but exhibited both polar and lateral cell localization in Delta flhFG cells. Polar localization of SflA required the polar landmark protein HubP. Over-expression of the C-terminal region of SflA (SflA(C)) in Delta flhFG Delta sflA cells suppressed the lateral flagellar formation. Our results suggest that SflA localizes with the flagella and that SflA(C) represses the flagellar initiation in Delta flhFG strains. A model is presented where SflA inhibits lateral flagellar formation to facilitate single polar flagellum assembly in V. alginolyticus cells.

DOI： 10.1111/gtc.12501

Biochemical characterization of the flagellar stator-associated inner membrane protein FliL from Vibrio alginolyticus Reviewed

Ananthanarayanan Kumar, Miyu Isumi, Mayuko Sakuma, Shiwei Zhu, Yuuki Nishino, Yasuhiro Onoue, Seiji Kojima, Yohei Miyanoiri, Katsumi Imada, Michio Homma

JOURNAL OF BIOCHEMISTRY Vol. 161 ( 4 ) page： 331 - 337 2017.4

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

The flagellar motor is embedded in the cell envelope and rotates upon interaction between the stator and the rotor. The rotation is powered by ion flow through the stator. A single transmembrane protein named FliL is associated with torque generation in the flagellar motor. We established an Escherichia coli over-expression system for FliL of Vibrio alginolyticus, a marine bacterium that has a sodium-driven polar flagellum. We successfully expressed, purified, and crystallized the ca. 17 kDa full-length FliL protein and generated a construct that expresses only the ca. 14 kDa periplasmic region of FliL (Delta TM FliL). Biochemical characterization and NMR analysis revealed that Delta TM FliL weakly interacted with itself to form an oligomer. We speculate that the observed dynamic interaction may be involved in the role of FliL in flagellar motor function.

DOI： 10.1093/jb/mvw076

Mutational analysis and overproduction effects of MotX, an essential component for motor function of Na+-driven polar flagella of Vibrio. International journal

Norihiro Takekawa, Seiji Kojima, Michio Homma

Journal of biochemistry Vol. 161 ( 2 ) page： 159 - 166 2017.2

Language：English Publishing type：Research paper (scientific journal)

The bacterial flagellar motor is a rotary motor complex composed of various proteins. The motor contains a central rod, multiple ring-like structures and stators. The Na+-driven polar flagellar motor of the marine bacterium Vibrio alginolyticus has a specific ring, called the ‘T-ring’, which consists of two periplasmic proteins, MotX and MotY. The T-ring is essential for assembly of the torque-generating unit, the PomA/PomB stator complex, into the motor. To investigate the role of the T-ring for motor function, we performed random mutagenesis of the motX gene on a plasmid. The isolated MotX mutants showed nonmotile, slow-motile, and up-motile phenotypes by the expression from the plasmid. Deletion analysis indicated that the C-terminal region and the signal peptide in MotX are not always essential for flagellar motor function. We also found that overproduction of MotX caused the delay of growth and aberrant cell shape. MotX might have unexpected roles not only in flagellar motor function but also in cell morphology control.

DOI： 10.1093/jb/mvw061

Structural and functional analysis of the C-terminal region of FliG, an essential motor component of Vibrio Na+-driven flagella. Reviewed

Miyanoiri Y, Hijikata A, Nishino Y, Gohara M, Onoue Y, Kojima S, Kojima C, Shirai T, Kainosho M, Homma M.

Structure Vol. 25 page： 1-9 2017

Localization and domain characterization of the SflA regulator of flagellar formation in Vibrio alginolyticus. Reviewed

Inaba S, Nishigaki T, Takekawa N, Kojima S, Homma M.

Genes Cells Vol. 7 page： 619-627 2017

Mechanism of Stator Assembly and Incorporation into the Flagellar Motor. Reviewed

Kojima S

Methods in molecular biology (Clifton, N.J.) Vol. 1593 page： 147 - 159 2017

Analysis of the GTPase motif of FlhF in the control of the number and location of polar flagella in Vibrio alginolyticus. Reviewed

Shota Kondo, Michio Homma, Seiji Kojima

Biophysics and physicobiology Vol. 14 page： 173 - 181 2017

Language：English Publishing type：Research paper (scientific journal)

Vibrio alginolyticus normally has a single polar flagellum whose number and placement are regulated positively by FlhF. FlhF is a GTPase and homolog of a signal recognition particle (SRP) protein called Ffh and SRP receptor FtsY. FlhF is located at the cell pole and directs formation of the flagellum. To study the mechanism of FlhF localization, we introduced random mutations into flhF by means of hydroxylamine and isolated mutants that could not generate the flagellum at the cell pole. The novel mutations were only mapped to the GTPase motif of FlhF. The mutant FlhF proteins showed reduced polar localization as compared to the wild type and still could associate with the membrane. These results support the assumption that the GTPase motif of FlhF plays a critical role in the polar localization of this protein during formation of the flagellum.

DOI： 10.2142/biophysico.14.0_173

HubP, a Polar Landmark Protein, Regulates Flagellar Number by Assisting in the Proper Polar Localization of FlhG in Vibrio alginolyticus Reviewed

Norihiro Takekawa, Soojin Kwon, Noriko Nishioka, Seiji Kojima, Michio Homma

JOURNAL OF BACTERIOLOGY Vol. 198 ( 22 ) page： 3091 - 3098 2016.11

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER SOC MICROBIOLOGY

The marine bacterium Vibrio alginolyticus has a single polar flagellum, the number of which is regulated positively by FlhF and negatively by FlhG. FlhF is intrinsically localized at the cell pole, whereas FlhG is localized there through putative interactions with the polar landmark protein HubP. Here we focused on the role of HubP in the regulation of flagellar number in V. alginolyticus. Deletion of hubP increased the flagellar number and completely disrupted the polar localization of FlhG. It was thought that the flagellar number is determined primarily by the absolute amount of FlhF localized at the cell pole. Here we found that deletion of hubP increased the flagellar number although it did not increase the polar amount of FlhF. We also found that FlhG overproduction did not reduce the polar localization of FlhF. These results show that the absolute amount of FlhF is not always the determinant of flagellar number. We speculate that cytoplasmic FlhG works as a quantitative regulator, controlling the amount of FlhF localized at the pole, and HubP-anchored polar FlhG works as a qualitative regulator, directly inhibiting the activity of polar FlhF. This regulation by FlhF, FlhG, and HubP might contribute to achieving optimal flagellar biogenesis at the cell pole in V. alginolyticus.
IMPORTANCE
For regulation of the flagellar number in marine Vibrio, two proteins, FlhF and FlhG, work as positive and negative regulators, respectively. In this study, we found that the polar landmark protein HubP is involved in the regulation of flagellar biogenesis. Deletion of hubP increased the number of flagella without increasing the amount of pole-localizing FlhF, indicating that the number of flagella is not determined solely by the absolute amount of pole-localizing FlhF, which is inconsistent with the previous model. We propose that cytoplasmic FlhG and HubP-anchored polar FlhG negatively regulate flagellar formation through two independent schemes.

DOI： 10.1128/JB.00462-16

The tetrameric MotA complex as the core of the flagellar motor stator from hyperthermophilic bacterium Reviewed

Norihiro Takekawa, Naoya Terahara, Takayuki Kato, Mizuki Gohara, Kouta Mayanagi, Atsushi Hijikata, Yasuhiro Onoue, Seiji Kojima, Tsuyoshi Shirai, Keiichi Namba, Michio Homma

SCIENTIFIC REPORTS Vol. 6 page： 31526 2016.8

Language：English Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

Rotation of bacterial flagellar motor is driven by the interaction between the stator and rotor, and the driving energy is supplied by ion influx through the stator channel. The stator is composed of the MotA and MotB proteins, which form a hetero-hexameric complex with a stoichiometry of four MotA and two MotB molecules. MotA and MotB are four-and single-transmembrane proteins, respectively. To generate torque, the MotA/MotB stator unit changes its conformation in response to the ion influx, and interacts with the rotor protein FliG. Here, we overproduced and purified MotA of the hyperthermophilic bacterium Aquifex aeolicus. A chemical crosslinking experiment revealed that MotA formed a multimeric complex, most likely a tetramer. The three-dimensional structure of the purified MotA, reconstructed by electron microscopy single particle imaging, consisted of a slightly elongated globular domain and a pair of arch-like domains with spiky projections, likely to correspond to the transmembrane and cytoplasmic domains, respectively. We show that MotA molecules can form a stable tetrameric complex without MotB, and for the first time, demonstrate the cytoplasmic structure of the stator.

DOI： 10.1038/srep31526

FliH and FliI ensure efficient energy coupling of flagellar type III protein export in Salmonella Reviewed

Tohru Minamino, Miki Kinoshita, Yumi Inoue, Yusuke V. Morimoto, Kunio Ihara, Satomi Koya, Noritaka Hara, Noriko Nishioka, Seiji Kojima, Michio Homma, Keiichi Namba

MICROBIOLOGYOPEN Vol. 5 ( 3 ) page： 424 - 435 2016.6

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-BLACKWELL

For construction of the bacterial flagellum, flagellar proteins are exported via its specific export apparatus from the cytoplasm to the distal end of the growing flagellar structure. The flagellar export apparatus consists of a transmembrane (TM) export gate complex and a cytoplasmic ATPase complex consisting of FliH, FliI, and FliJ. FlhA is a TM export gate protein and plays important roles in energy coupling of protein translocation. However, the energy coupling mechanism remains unknown. Here, we performed a cross-complementation assay to measure robustness of the energy transduction system of the export apparatus against genetic perturbations. Vibrio FlhA restored motility of a Salmonella flhA mutant but not that of a fliH-fliI flhB(P28T) flhA mutant. The flgM mutations significantly increased flagellar gene expression levels, allowing Vibrio FlhA to exert its export activity in the fliH-fliI flhB(P28T) flhA mutant. Pull-down assays revealed that the binding affinities of Vibrio FlhA for FliJ and the FlgN-FlgK chaperone-substrate complex were much lower than those of Salmonella FlhA. These suggest that Vibrio FlhA requires the support of FliH and FliI to efficiently and properly interact with FliJ and the FlgN-FlgK complex. We propose that FliH and FliI ensure robust and efficient energy coupling of protein export during flagellar assembly.

DOI： 10.1002/mbo3.340

Serine suppresses the motor function of a periplasmic PomB mutation in the Vibrio flagella stator Reviewed

Tatsuro Nishikino, Shiwei Zhu, Norihiro Takekawa, Seiji Kojima, Yasuhiro Onoue, Michio Homma

GENES TO CELLS Vol. 21 ( 5 ) page： 505 - 516 2016.5

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-BLACKWELL

The flagellar motor of Vibrio alginolyticus is made of two parts: a stator consisting of proteins PomA and PomB, and a rotor whose main component is FliG. The interaction between FliG and PomA generates torque for flagellar rotation. Based on cross-linking experiments of double-Cys mutants of PomB, we previously proposed that a conformational change in the periplasmic region of PomB caused stator activation. Double-Cys mutants lost their motility due to an intramolecular disulfide bridge. In this study, we found that the addition of serine, a chemotactic attractant, to a PomB(L160C/I186C) mutant restored motility without cleaving the disulfide bridge. We speculate that serine changed the rotor (FliG) conformation, affecting rotational direction. Combined with the counterclockwise (CCW)-biased mutation FliG(G214S), motility of PomB(L160C/I186C) was restored without the addition of serine. Likewise, motility was restored without serine in Che(-) mutants, in either a CCW-locked or clockwise (CW)-locked strain. In contrast, in a cheY (CCW-locked) strain, Vibrio (L160C/I186C) required serine to be rescued. We speculate that CheY affects stator conformation and motility restoration by serine is independent on the chemotaxis signaling pathway.

DOI： 10.1111/gtc.12357

細菌べん毛の回転および本数制御機構に関する研究 Invited

小嶋誠司

日本細菌学雑誌 Vol. 71 ( 3 ) page： 185-197 2016

Studies on the mechanism of bacterial flagellar rotation and the flagellar number regulation. Reviewed

Seiji Kojima

Nihon saikingaku zasshi. Japanese journal of bacteriology Vol. 71 ( 3 ) page： 185 - 97 2016

Language：Japanese Publishing type：Research paper (scientific journal)

Many motile bacteria have the motility organ, the flagellum. It rotates by the rotary motor driven by the ion-motive force and is embedded in the cell surface at the base of each flagellar filament. Many researchers have been studying its rotary mechanism for years, but most of the energy conversion processes have been remained in mystery. We focused on the flagellar stator, which works at the core process of energy conversion, and found that the periplasmic region of the stator changes its conformation to be activated only when the stator units are incorporated into the motor and anchored at the cell wall. Meanwhile, the physiologically important supramolecular complex is localized in the cell at the right place and the right time with a proper amount. How the cell achieves such a proper localization is the fundamental question for life science, and we undertake this problem by analyzing the mechanism for biogenesis of a single polar flagellum of Vibrio alginolyticus. Here I describe the molecular mechanism of how the flagellum is generated at the specific place with a proper number, and also how the flagellar stator is incorporated into the motor to complete the functional motor assembly, based on our studies.

DOI： 10.3412/jsb.71.185

Effect of FliG three amino acids deletion in Vibrio polar-flagellar rotation and formation Reviewed

Yasuhiro Onoue, Seiji Kojima, Michio Homma

JOURNAL OF BIOCHEMISTRY Vol. 158 ( 6 ) page： 523 - 529 2015.12

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

Most of bacteria can swim by rotating flagella bidirectionally. The C ring, located at the bottom of the flagellum and in the cytoplasmic space, consists of FliG, FliM and FliN, and has an important function in flagellar protein secretion, torque generation and rotational switch of the motor. FliG is the most important part of the C ring that interacts directly with a stator subunit. Here, we introduced a three-amino acids in-frame deletion mutation (Delta PSA) into FliG from Vibrio alginolyticus, whose corresponding mutation in Salmonella confers a switch-locked phenotype, and examined its phenotype. We found that this FliG mutant could not produce flagellar filaments in a fliG null strain but the FliG(Delta PSA) protein could localize at the cell pole as does the wild-type protein. Unexpectedly, when this mutant was expressed in a wild-type strain, cells formed flagella efficiently but the motor could not rotate. We propose that this different phenotype in Vibrio and Salmonella might be due to distinct interactions between FliG mutant and FliM in the C ring between the bacterial species.

DOI： 10.1093/jb/mvv068

Dynamism and regulation of the stator, the energy conversion complex of the bacterial flagellar motor Reviewed

Seiji Kojima

CURRENT OPINION IN MICROBIOLOGY Vol. 28 page： 66 - 71 2015.12

Language：English Publisher：CURRENT BIOLOGY LTD

Many motile bacteria swim by rotating their motility organ, the flagellum. Rotation of the flagellum is driven by a motor at its base, and torque is generated by the rotor stator interaction coupled with the specific ion flow through the channel in the stator. Because the stator works as an energy-conversion complex in the motor, understanding the functional mechanism of the stator is critically important. But its characterization has been hampered due to the difficulty in isolating the functional stator complex from the membrane. Recently, successful new approaches for studying the stator have been reported that reveal its novel properties. Two of those, visualization of the in vivo behavior of stator units using fluorescently tagged proteins and structure-guided functional analyses of the soluble region in the stator, are summarized in this short review.

DOI： 10.1016/j.mib.2015.07.015

FliL associates with the stator to support torque generation of the sodium-driven polar flagellar motor of Vibrio Reviewed

Shiwei Zhu, Ananthanarayanan Kumar, Seiji Kojima, Michio Homma

MOLECULAR MICROBIOLOGY Vol. 98 ( 1 ) page： 101 - 110 2015.10

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-BLACKWELL

Flagellar motors generate torque to rotate flagellar filaments and drive bacterial cells. Each motor is composed of a rotor and many stators. The stator is a force-generating complex that converts ion flux into torque. Previous reports have suggested that the membrane protein FliL is located near the stator and is involved in torque generation. We investigated the role of FliL in the sodium-driven polar flagellar motor of Vibrio alginolyticus. Our results revealed that FliL is a cytoplasmic membrane protein and is located at the base of flagellum. The deletion of fliL did not affect the cell morphology or flagellation but resulted in a significant decrease of swimming speed, especially at a higher load thus suggesting that FliL is important for torque generation at high load conditions. Furthermore, the polar localization of the stator was decreased in a Delta fliL mutant, but the sodium-dependent assembly of the stator complex was still retained. The polar localization of FliL was lost in the absence of the stator complex, indicating that FliL interacts directly or indirectly with the stator. Our results suggest that FliL is localized along with the stator in order to support the motor functioning for swimming at high load conditions by maintaining the stator assembly.

DOI： 10.1111/mmi.13103

The MinD homolog FlhG regulates the synthesis of the single polar flagellum of Vibrio alginolyticus Reviewed

Hiroki Ono, Akari Takashima, Hikaru Hirata, Michio Homma, Seiji Kojima

MOLECULAR MICROBIOLOGY Vol. 98 ( 1 ) page： 130 - 141 2015.10

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-BLACKWELL

FlhG, a MinD homolog and an ATPase, is known to mediate the formation of the single polar flagellum of Vibrio alginolyticus together with FlhF. FlhG and FlhF work antagonistically, with FlhF promoting flagellar assembly and FlhG inhibiting it. Here, we demonstrate that purified FlhG exhibits a low basal ATPase activity. As with MinD, the basal ATPase activity of FlhG can be activated and the D171A residue substitution enhances its ATPase activity sevenfold. FlhG-D171A localizes strongly at the cell pole and severely inhibits motility and flagellation, whereas the FlhG K31A and K36Q mutants, which are defective in ATP binding, do not localize to the poles, cannot complement a flhG mutant and lead to hyperflagellation. A strong polar localization of FlhF is observed with the K36Q mutant FlhG but not with the wild-type or D171A mutant FlhG. Unexpectedly, an Ala substitution at the catalytic residue (D60A), which abolishes ATPase activity but still allows ATP binding, only slightly affects FlhG functions. These results suggest that the ATP-dependent polar localization of FlhG is crucial for its ability to downregulate the number of polar flagella. We speculate that ATP hydrolysis by FlhG is required for the fine tuning of the regulation.

DOI： 10.1111/mmi.13109

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

Norihiro Takekawa, Masayoshi Nishiyama, Tsuyoshi Kaneseki, Tamotsu Kanai, Haruyuki Atomi, Seiji Kojima, Michio Homma

SCIENTIFIC REPORTS Vol. 5 page： 12711 2015.8

Language：English Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

Aquifex aeolicus is a hyperthermophilic, hydrogen-oxidizing and carbon-fixing bacterium that can grow at temperatures up to 95 degrees 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 mu m s(-1) at 85 degrees 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.

DOI： 10.1038/srep12711

Functional chimeras of flagellar stator proteins between E-coli MotB and Vibrio PomB at the periplasmic region in Vibrio or E-coli Reviewed

Yuuki Nishino, Yasuhiro Onoue, Seiji Kojima, Michio Homma

MICROBIOLOGYOPEN Vol. 4 ( 2 ) page： 323 - 331 2015.4

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-BLACKWELL

The bacterial flagellar motor has a stator and a rotor. The stator is composed of two membrane proteins, MotA and MotB in Escherichia coli and PomA and PomB in Vibrio alginolyticus. The Vibrio motor has a unique structure, the T ring, which is composed of MotX and MotY. Based on the structural information of PomB and MotB, we constructed three chimeric proteins between PomB and MotB, named PotB(91), PotB(129,) and PotB(138), with various chimeric junctions. When those chimeric proteins were produced with PomA in a motAB strain of E. coli or in pomAB and pomAB motX strains of Vibrio, all chimeras were functional in E. coli or Vibrio, either with or without the Tring, although the motilities were very weak in E. coli. Furthermore, we could isolate some suppressors in E. coli and identified the mutation sites on PomA or the chimeric B subunit. The weak function of chimeric PotBs in E. coli is derived mainly from the defect in the rotational switching of the flagellar motor. In addition, comparing the motilities of chimera strains in pomAB, PotB(138) had the highest motility. The difference between the origin of the 1 and 2 helices, E. coli MotB or Vibro PomB, seems to be important for motility in E. coli and especially in Vibrio.

DOI： 10.1002/mbo3.240

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