Crystal Structure of the Flagellar Rotor Protein FliN from
            <i>Thermotoga maritima</i>

Brown, Perry N.; Mathews, Michael A. A.; Joss, Lisa; Hill, Christopher P.; Blair, David F.

doi:10.1128/jb.187.8.2890-2902.2005

Cited by 120 publications

(169 citation statements)

References 77 publications

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“…Structures of V-ATPase (PDB ID code 3J0J) and FliJ (PDB ID code 3AJW) were used to build the model of the Spa47-Spa13-MxiN complex. Six FliN tetramers (PDB ID code 1YAB) (35) were placed into the six ring-shaped densities at the bottom, with the hydrophobic patch interacting with the MxiN linkers.…”

Section: Methodsmentioning

confidence: 99%

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Visualization of the type III secretion sorting platform of Shigella flexneri

Hu¹,

Morado²,

Margolin³

et al. 2015

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

204

300

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Bacterial type III secretion machines are widely used to inject virulence proteins into eukaryotic host cells. These secretion machines are evolutionarily related to bacterial flagella and consist of a large cytoplasmic complex, a transmembrane basal body, and an extracellular needle. The cytoplasmic complex forms a sorting platform essential for effector selection and needle assembly, but it remains largely uncharacterized. Here we use high-throughput cryoelectron tomography (cryo-ET) to visualize intact machines in a virulent Shigella flexneri strain genetically modified to produce minicells capable of interaction with host cells. A high-resolution in situ structure of the intact machine determined by subtomogram averaging reveals the cytoplasmic sorting platform, which consists of a central hub and six spokes, with a pod-like structure at the terminus of each spoke. Molecular modeling of wild-type and mutant machines allowed us to propose a model of the sorting platform in which the hub consists mainly of a hexamer of the Spa47 ATPase, whereas the MxiN protein comprises the spokes and the Spa33 protein forms the pods. Multiple contacts among those components are essential to align the Spa47 ATPase with the central channel of the MxiA protein export gate to form a unique nanomachine. The molecular architecture of the Shigella type III secretion machine and its sorting platform provide the structural foundation for further dissecting the mechanisms underlying type III secretion and pathogenesis and also highlight the major structural distinctions from bacterial flagella.nanomachine | injectisome | pathogen-host interaction | cryo-electron tomography | protein secretion

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Section: Methodsmentioning

confidence: 99%

“…The C-terminal region of Spa33 is homologous to the flagellar protein FliN (SI Appendix, Table S5), which has been proposed to form a homotetramer (34,35) at the bottom of the flagellar C ring.…”

Section: The Presence Of Mxin or Spa33 Has A Dramatic Impact On T3ss mentioning

confidence: 99%

Visualization of the type III secretion sorting platform of Shigella flexneri

Hu¹,

Morado²,

Margolin³

et al. 2015

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

204

300

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“…1B. In this model, FliG is at the top of the C-ring, where it can interact with the stator; FliM is just below FliG and forms the relatively smooth side wall of the ring; and FliN is at the bottom, where the EM images show rings of density of a shape and size that match the donut-shaped FliN tetramers observed in the crystal structure (30). The model can account satisfactorily for the overall shape and dimensions of the C-ring, as well as for results from diverse mutational and biochemical studies (36, 38 -41).…”

mentioning

confidence: 99%

“…For FliN, the structure is known for the C-terminal two-thirds of the protein, lacking only an N-terminal region that is relatively poorly conserved and largely dispensable for function (35). The FliN subunits are tightly intertwined into dimers, which are further associated, in one crystal form, into donut-shaped tetramers (30). The E. coli FliN protein was shown to form stable tetramers in solution (30), and targeted disulfide cross-linking experiments indicated a donut-like organization for the protein in the cell (36).…”

mentioning

confidence: 99%

“…The FliN subunits are tightly intertwined into dimers, which are further associated, in one crystal form, into donut-shaped tetramers (30). The E. coli FliN protein was shown to form stable tetramers in solution (30), and targeted disulfide cross-linking experiments indicated a donut-like organization for the protein in the cell (36). A conserved hydrophobic patch on FliN, centered on the dimer 2-fold axis, forms a site of interaction with the flagellar export protein FliH (11,13).…”

mentioning

confidence: 99%

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Subunit Organization and Reversal-associated Movements in the Flagellar Switch of Escherichia coli

Sarkar

Paul

Blair

2010

Journal of Biological Chemistry

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Bacterial flagella contain a rotor-mounted protein complex termed the switch complex that functions in flagellar assembly, rotation, and clockwise/counterclockwise direction control. In Escherichia coli and Salmonella, the switch complex contains the proteins FliG, FliM, and FliN and corresponds structurally with the C-ring in the flagellar basal body. Certain features of subunit organization in the switch complex have been deduced previously, but details of subunit organization in the lower part of the C-ring and the molecular movements responsible for motor switching remain unclear. In this study, we use crosslinking, binding, and mutational experiments to examine subunit organization in the bottom of the C-ring and to probe movements that occur upon switching. The results show that FliN tetramers alternate with FliM C-terminal domains to form the bottom of the C-ring in an arrangement that closely reproduces the major features observed in electron microscopic reconstructions. When motors were switched to clockwise rotation by a repellent stimulus, cross-link yields were altered in a pattern indicating relative movement of FliN and FliM C . These results are discussed in the framework of a structurally grounded hypothesis for the switching mechanism.

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Bacterial Flagella: Flagellar Motor

Wadhams

Sowa

2009

Encyclopedia of Life Sciences

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The bacterial flagellar motor is a complex biological rotary molecular motor which is situated in the cell envelopes of bacteria. Whereas most biological motors use adenosine triphosphate (ATP) as their energy source, the rotation of the flagellar motor is driven by a flow of charged ions across the bacterial plasma membrane. The motor powers the rotation of helical flagellar filaments at speeds of up to several hundred hertz. These rotating filaments act like propellers, pushing the cells through their environment. The motors are regulated by one of the best‐characterized biological signalling pathways, the chemotaxis pathway. This pathway changes the swimming pattern of the bacteria in response to changes in the concentration of external chemicals so that they move into environments which are optimal for their growth. Key concepts: Bacteria swim using a small biological rotary motor which is powered by the movement of charged ions across the plasma membrane. The flagellar motor consists of a rotor which rotates against stator units that are anchored to the peptidoglycan cell wall. Torque is generated by the interaction of the stator units, MotA and MotB, with FliG in the rotor. Despite the fact that the driving ions always flow in one direction through the stator units, many flagellar motors can switch between clockwise and counterclockwise rotation. A complex signalling pathway regulates the motor output in response to environmental signals ensuring that bacteria swim towards nutrient rich environments.

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Crystal Structure of the Flagellar Rotor Protein FliN from Thermotoga maritima

Cited by 120 publications

References 77 publications

Visualization of the type III secretion sorting platform of Shigella flexneri

Visualization of the type III secretion sorting platform of Shigella flexneri

Subunit Organization and Reversal-associated Movements in the Flagellar Switch of Escherichia coli

Bacterial Flagella: Flagellar Motor

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