Length of the Flagellar Hook and the Capacity of the Type III Export Apparatus

Makishima, Shigeru; Komoriya, Kaoru; Yamaguchi, Shigeru; Aizawa, Shin‐Ichi

doi:10.1126/science.1058366

Cited by 95 publications

(102 citation statements)

References 26 publications

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“…The remaining positions that gave a mot phenotype (positions 121 and 122) were together on the side surfaces of the tetramer, where they might participate in interactions that stabilize the C ring. One of these mutations (at position 122) was found to cause a reduction in the length of the flagellar hook (43). This might indicate that FliN has a role in binding to hook subunits, as proposed by Makishima and coworkers (43), but it is also consistent with a more general role for FliN in flagellar assembly.…”

Section: Discussionsupporting

confidence: 57%

Crystal Structure of the Flagellar Rotor Protein FliN from Thermotoga maritima

Brown¹,

et al. 2005

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FliN is a component of the bacterial flagellum that is present at levels of more than 100 copies and forms the bulk of the C ring, a drum-shaped structure at the inner end of the basal body. FliN interacts with FliG and FliM to form the rotor-mounted switch complex that controls clockwise-counterclockwise switching of the motor. In addition to its functions in motor rotation and switching, FliN is thought to have a role in the export of proteins that form the exterior structures of the flagellum (the rod, hook, and filament). Here, we describe the crystal structure of most of the FliN protein of Thermotoga maritima.

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Section: Discussionsupporting

confidence: 57%

Crystal Structure of the Flagellar Rotor Protein FliN from Thermotoga maritima

Brown¹,

et al. 2005

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“…These results suggest that the S. flexneri needle and Salmonella hook are both still controlled even in the absence of Spa32 and FliK, respectively. Recent studies have led to the hypothesis that the C-ring compartment formed in the cytoplasm beneath the MS ring is involved in determining the length of the hook on the flagellar basal body (13,21,27,30). The C-ring is predicted to function as a compartment for the storage of a fixed amount of the flagellar hook component FlgE proteins, although there is no direct evidence yet that FlgE fills the C-ring, and thus the mechanism of length control of the hook is still largely speculative (30).…”

Section: Resultsmentioning

confidence: 99%

“…Recent studies have led to the hypothesis that the C-ring compartment formed in the cytoplasm beneath the MS ring is involved in determining the length of the hook on the flagellar basal body (13,21,27,30). The C-ring is predicted to function as a compartment for the storage of a fixed amount of the flagellar hook component FlgE proteins, although there is no direct evidence yet that FlgE fills the C-ring, and thus the mechanism of length control of the hook is still largely speculative (30). In S. flexneri, it is worth noting that the type III secretion machinery is also indicated to possess a compartment, like the flagellar C-ring, beneath the basal body, named the bulb structure, as investigated in the osmotically shocked Shigella envelope by TEM (3).…”

Section: Resultsmentioning

confidence: 99%

Shigella Spa32 Is an Essential Secretory Protein for Functional Type III Secretion Machinery and Uniformity of Its Needle Length

et al. 2002

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The Shigella type III secretion machinery is responsible for delivering to host cells the set of effectors required for invasion. The type III secretion complex comprises a needle composed of MxiH and MxiI and a basal body made up of MxiD, MxiG, and MxiJ. In S. flexneri, the needle length has a narrow range, with a mean of approximately 45 nm, suggesting that it is strictly regulated. Here we show that Spa32, encoded by one of the spa genes, is an essential protein translocated via the type III secretion system and is involved in the control of needle length as well as type III secretion activity. When the spa32 gene was mutated, the type III secretion complexes possessed needles of various lengths, ranging from 40 to 1,150 nm. Upon introduction of a cloned spa32 into the spa32 mutant, the bacteria produced needles of wild-type length. The spa32 mutant overexpressing MxiH produced extremely long (>5 m) needles. Spa32 was secreted into the medium via the type III secretion system, but secretion did not depend on activation of the system. The spa32 mutant and the mutant overexpressing MxiH did not secrete effectors such as Ipa proteins into the medium or invade HeLa cells. Upon introduction of Salmonella invJ, encoding InvJ, which has 15.4% amino acid identity with Spa32, into the spa32 mutant, the bacteria produced type III needles of wild-type length and efficiently entered HeLa cells. These findings suggest that Spa32 is an essential secreted protein for a functional type III secretion system in Shigella spp. and is involved in the control of needle length. Furthermore, its function is interchangeable with that of Salmonella InvJ.The type III protein secretion system is found among various gram-negative animal-and plant-pathogenic bacteria, in which the subsets of effector proteins that are secreted via the system into host cells have crucial roles in the bacterial infection process (8,9,16,38). Genetic and functional studies indicate that the type III secretion system requires proteins encoded by more than 20 genes, which contain the structural components of the secretion complex, secreted proteins, chaperones, and regulators (10,11,19,37,43). In Shigella spp., the system is encoded by approximately 20 genes located in the mxi and spa operons on a large 230-kb plasmid (5, 19). The proteins of the type III secretion system show considerable amino acid homology among different pathogens, and some of them also show amino acid homology with the components of the bacterial flagellar export system (26). Although the function of the type III secretion system in bacterial infection is distinct from that of the flagellar export system, the type III secretion system is believed to have evolved from the flagellar export system and diverged in each pathogen to become involved in the infection process (15).Recent studies indicate that the type III secretion complexes of Shigella flexneri and Salmonella spp. share structural similarities; the complexes are composed of two distinct parts, a basal body and a needle. The basal...

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“…While the molecular ruler or tape measure model is now a widely accepted working hypothesis for FliK function, hook length control was initially considered to be controlled by the capacity of the C ring to be filled with a defined amount of the hook protein FlgE (measuring cup model). This theory was based on the observation that the lack of the C-ring component FliG, FliM, or FliN led to shorter hooks (342). According to the measuring cup model, emptying the C ring would allow access of FliK to FlhB C and thus would allow the switch to occur.…”

Section: T3s Substrate Specificity Switching In Flagellar T3s Systemsmentioning

confidence: 99%

“…According to the measuring cup model, emptying the C ring would allow access of FliK to FlhB C and thus would allow the switch to occur. However, the C ring can be filled with 50 FlgE hook subunits at most, while at least 120 subunits are required to reach the average hook length (342,476). This implies that the C ring would have to be emptied several times before the substrate specificity switch occurs.…”

Section: T3s Substrate Specificity Switching In Flagellar T3s Systemsmentioning

confidence: 99%

Protein Export According to Schedule: Architecture, Assembly, and Regulation of Type III Secretion Systems from Plant- and Animal-Pathogenic Bacteria

Büttner

2012

Microbiol Mol Biol Rev

363

482

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SUMMARY Flagellar and translocation-associated type III secretion (T3S) systems are present in most Gram-negative plant- and animal-pathogenic bacteria and are often essential for bacterial motility or pathogenicity. The architectures of the complex membrane-spanning secretion apparatuses of both systems are similar, but they are associated with different extracellular appendages, including the flagellar hook and filament or the needle/pilus structures of translocation-associated T3S systems. The needle/pilus is connected to a bacterial translocon that is inserted into the host plasma membrane and mediates the transkingdom transport of bacterial effector proteins into eukaryotic cells. During the last 3 to 5 years, significant progress has been made in the characterization of membrane-associated core components and extracellular structures of T3S systems. Furthermore, transcriptional and posttranscriptional regulators that control T3S gene expression and substrate specificity have been described. Given the architecture of the T3S system, it is assumed that extracellular components of the secretion apparatus are secreted prior to effector proteins, suggesting that there is a hierarchy in T3S. The aim of this review is to summarize our current knowledge of T3S system components and associated control proteins from both plant- and animal-pathogenic bacteria.

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Length of the Flagellar Hook and the Capacity of the Type III Export Apparatus

Cited by 95 publications

References 26 publications

Crystal Structure of the Flagellar Rotor Protein FliN from Thermotoga maritima

Crystal Structure of the Flagellar Rotor Protein FliN from Thermotoga maritima

Shigella Spa32 Is an Essential Secretory Protein for Functional Type III Secretion Machinery and Uniformity of Its Needle Length

Protein Export According to Schedule: Architecture, Assembly, and Regulation of Type III Secretion Systems from Plant- and Animal-Pathogenic Bacteria

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