Helical Packing of Needles from Functionally Altered Shigella Type III Secretion Systems

Cordes, Frank; Daniell, Sarah; Kenjale, Roma; Saurya, Saroj; Picking, Wendy L.; Picking, William D.; Booy, Frank P.; Lea, Susan M.; Blocker, Ariel

doi:10.1016/j.jmb.2005.09.062

Cited by 39 publications

(54 citation statements)

References 21 publications

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“…1B). The refined helical parameters are 4.30 Å for the axial rise and 64.1°for the azimuthal rotation along the 1-start helix ( Table 2) confirming previous data (4,14). However, none of the available atomic models of MxiH and its homologs ( Fig.…”

Section: Resultssupporting

confidence: 80%

“…Using a 16-Å resolution 3D-image reconstruction of the needle from negative-stain EM images (4), a pseudoatomic model of the needle was generated (12). However, neither this nor EM analysis of the helical parameters of deregulated mutants (14) revealed how the needle controls secretion. The recent electron cryomicroscopy (cryo-EM) image reconstruction of the Salmonella needle did not reveal the structural architecture in detail either, due to its limited resolution (15).…”

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confidence: 99%

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Structure of a type III secretion needle at 7-Å resolution provides insights into its assembly and signaling mechanisms

Fujii

Cheung

Blanco

et al. 2012

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

114

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Type III secretion systems of Gram-negative bacteria form injection devices that deliver effector proteins into eukaryotic cells during infection. They span both bacterial membranes and the extracellular space to connect with the host cell plasma membrane. Their extracellular portion is a needle-like, hollow tube that serves as a secretion conduit for effector proteins. The needle of Shigella flexneri is approximately 50-nm long and 7-nm thick and is made by the helical assembly of one protein, MxiH. We provide a 7-Å resolution 3D image reconstruction of the Shigella needle by electron cryomicroscopy, which resolves α-helices and a β-hairpin that has never been observed in the crystal and solution structures of needle proteins, including MxiH. An atomic model of the needle based on the 3D-density map, in comparison with that of the bacterial-flagellar filament, provides insights into how such a thin tubular structure is stably assembled by intricate intermolecular interactions. The map also illuminates how the needle-length control protein functions as a ruler within the central channel during export of MxiH for assembly at the distal end of the needle, and how the secretion-activation signal may be transduced through a conformational change of the needle upon host-cell contact.helical image analysis | Shigella pathogenesis | bacterial protein secretion

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Section: Resultssupporting

confidence: 80%

mentioning

confidence: 99%

Structure of a type III secretion needle at 7-Å resolution provides insights into its assembly and signaling mechanisms

Fujii

Cheung

Blanco

et al. 2012

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

114

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“…We have previously proposed that signaling occurred via changes in the helical architecture of the needle in ways analogous to those known to control flagellar filament switching. EM studies failed to detect alterations in the helical architecture of functionally altered mutant needles (25). However, mapping onto our needle model of a mutant (D73A) that leads to uncontrolled secretion and also renders the needle insensitive to all further forms of activation (11) provides some insight.…”

Section: Resultsmentioning

confidence: 85%

“…2 B and C), whereas the B molecule is not consistent with the observed needle density (CC ϭ 47% for optimized positioning of molecule B). Although the conformation of the B molecule may be induced by crystal packing, it is also possible that it reflects the structure of the needle subunit when the needle is in a different activation state from that for which we have an EM reconstruction (16,25). The C-terminal helix forms the outer shell of the needle core, whereas the PSNP loop directs the N-terminal helix to line the inner wall of the needle channel.…”

Section: Resultsmentioning

confidence: 99%

Molecular model of a type III secretion system needle: Implications for host-cell sensing

Deane

Roversi

Cordes

et al. 2006

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

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151

286

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Type III secretion systems are essential virulence determinants for many Gram-negative bacterial pathogens. The type III secretion system consists of cytoplasmic, transmembrane, and extracellular domains. The extracellular domain is a hollow needle protruding above the bacterial surface and is held within a basal body that traverses both bacterial membranes. Effector proteins are translocated, via this external needle, directly into host cells, where they subvert normal cell functions to aid infection. Physical contact with host cells initiates secretion and leads to formation of a pore, thought to be contiguous with the needle channel, in the host-cell membrane. Here, we report the crystal structure of the Shigella flexneri needle subunit MxiH and a complete model for the needle assembly built into our three-dimensional EM reconstruction. The model, combined with mutagenesis data, reveals that signaling of host-cell contact is relayed through the needle via intersubunit contacts and suggests a mode of binding for a tip complex.needle complex ͉ protein secretion ͉ Shigella

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“…Hence, the detection of CdsF trimers or dimers could reflect an alteration in helical assembly. Alternatively, Cordes et al (6) reported that MxiH mutants affecting secretion activity do not change helical packing. In this case, the alteration in cross-linking pattern could correspond to states in which CdsF is interacting with different proteins.…”

Section: Vol 190 2008mentioning

confidence: 99%

Bioinformatic and Biochemical Evidence for the Identification of the Type III Secretion System Needle Protein ofChlamydia trachomatis

et al. 2008

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Chlamydia spp. express a functional type III secretion system (T3SS) necessary for pathogenesis and intracellular growth. However, certain essential components of the secretion apparatus have diverged to such a degree as to preclude their identification by standard homology searches of primary protein sequences. One example is the needle subunit protein. Electron micrographs indicate that chlamydiae possess needle filaments, and yet database searches fail to identify a SctF homologue. We used a bioinformatics approach to identify a likely needle subunit protein for Chlamydia. Experimental evidence indicates that this protein, designated CdsF, has properties consistent with it being the major needle subunit protein. CdsF is concentrated in the outer membrane of elementary bodies and is surface exposed as a component of an extracellular needle-like projection. During infection CdsF is detectible by indirect immunofluorescence in the inclusion membrane with a punctuate distribution adjacent to membrane-associated reticulate bodies. Biochemical cross-linking studies revealed that, like other SctF proteins, CdsF is able to polymerize into multisubunit complexes. Furthermore, we identified two chaperones for CdsF, termed CdsE and CdsG, which have many characteristics of the Pseudomonas spp. needle chaperones PscE and PscG, respectively. In aggregate, our data are consistent with CdsF representing at least one component of the extended Chlamydia T3SS injectisome. The identification of this secretion system component is essential for studies involving ectopic reconstitution of the Chlamydia T3SS. Moreover, we anticipate that CdsF could serve as an efficacious target for anti-Chlamydia neutralizing antibodies.

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Helical Packing of Needles from Functionally Altered Shigella Type III Secretion Systems

Cited by 39 publications

References 21 publications

Structure of a type III secretion needle at 7-Å resolution provides insights into its assembly and signaling mechanisms

Structure of a type III secretion needle at 7-Å resolution provides insights into its assembly and signaling mechanisms

Molecular model of a type III secretion system needle: Implications for host-cell sensing

Bioinformatic and Biochemical Evidence for the Identification of the Type III Secretion System Needle Protein ofChlamydia trachomatis

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