Bile Salts Stimulate Recruitment of IpaB to the
            <i>Shigella flexneri</i>
            Surface, Where It Colocalizes with IpaD at the Tip of the Type III Secretion Needle

Olive, Andrew J.; Kenjale, Roma; Espina, Marianela; Moore, David S.; Picking, Wendy L.; Picking, William D.

doi:10.1128/iai.01599-06

Cited by 124 publications

(205 citation statements)

References 14 publications

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“…5 Shigella is currently the only pathogen for which each step in the T3SA needle tip complex maturation can be artificially induced to mimic natural maturation. [6][7][8] As a first step of Shigella T3SA maturation, IpaD forms a pentameric structure at the tip of the nascent MxiH needle. 9 In its capacity as an environmental sensor, IpaD detects small molecules such as deoxycholate (DOC), promoting a conformational change in IpaD that results in the recruitment of IpaB, the first translocator, to the maturing T3SA needle tip.…”

Section: Introductionmentioning

confidence: 99%

“…9 In its capacity as an environmental sensor, IpaD detects small molecules such as deoxycholate (DOC), promoting a conformational change in IpaD that results in the recruitment of IpaB, the first translocator, to the maturing T3SA needle tip. 7,[10][11][12] IpaB then interacts with cholesterol and sphingolipid rich host cell membranes, which can be mimicked using defined liposomes. 8 The interaction of IpaB with host cells or cholesterol/sphingolipid rich liposomes recruits IpaC, the second translocator, 8,13 to assemble the final T3SA needle tip complex, which results in formation of the translocon pore.…”

Section: Introductionmentioning

confidence: 99%

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Oligomeric states of the Shigella translocator protein IpaB provide structural insights into formation of the type III secretion translocon

et al. 2013

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The Shigella flexneri Type III secretion system (T3SS) senses contact with human intestinal cells and injects effector proteins that promote pathogen entry as the first step in causing life threatening bacillary dysentery (shigellosis). The Shigella Type III secretion apparatus (T3SA) consists of an anchoring basal body, an exposed needle, and a temporally assembled tip complex. Exposure to environmental small molecules recruits IpaB, the first hydrophobic translocator protein, to the maturing tip complex. IpaB then senses contact with a host cell membrane, forming the translocon pore through which effectors are delivered to the host cytoplasm. Within the bacterium, IpaB exists as a heterodimer with its chaperone IpgC; however, IpaB's structural state following secretion is unknown due to difficulties isolating stable protein.We have overcome this by coexpressing the IpaB/IpgC heterodimer and isolating IpaB by incubating the complex in mild detergents. Interestingly, preparation of IpaB with n-octyl-oligooxyethylene (OPOE) results in the assembly of discrete oligomers while purification in N,Ndimethyldodecylamine N-oxide (LDAO) maintains IpaB as a monomer. In this study, we demonstrate that IpaB tetramers penetrate phospholipid membranes to allow a size-dependent release of small molecules, suggesting the formation of discrete pores. Monomeric IpaB also interacts with liposomes but fails to disrupt them. From these and additional findings, we propose Abbreviations: AUC, analytical ultracentrifugation; CD, circular dichroism; CMC, critical micelle concentration; DGS-NTA, 1,2-dioleoylsn-glycero-3-[(N-(5-amino-1-carboxypentyl) iminodiacetic acid)succinyl]; DLS, dynamic light scattering; DMSO, dimethyl sulfoxide; DOPC, dioleoylphosphatidylcholine; DOPG, dioleoylphosphatidylglycerol; DSP, dithiobis[succinimidyl proprionate; FM, fluorescein maleimide; FRET, F-rster resonance energy transfer; Ipa, invasion plasmid antigen; Ipg, invasion plasmid gene; LDAO, N,N-dimethyldodecylamine N-oxide; Mxi, major exporter of Ipas; OPOE, n-Octyl-oligo-oxyethylene; SATA, N-succinimidyl-S-acetylthioacetate; SEC, size exclusion chromatography; SRB, sulforhodamine B; T m , thermal unfolding midpoint; TCEP, (tris (2-carboxyethyl)phosphine; TRITC DHPE, (N-(6-tetramethylrhodaminethiocarbamoyl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine); T3SS, type-III secretion system; T3SA, type III secretion apparatus.Additional Supporting Information may be found in the online version of this article. that IpaB can exist as a tetramer having inherent flexibility, which allows it to cooperatively interact with and insert into host cell membranes. This event may then lay the foundation for formation of the Shigella T3SS translocon pore.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Oligomeric states of the Shigella translocator protein IpaB provide structural insights into formation of the type III secretion translocon

et al. 2013

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“…This issue is complex and has recently been reviewed (1, 2), we therefore do not touch on this issue here. After needle completion other proteins are secreted through the needle and assemble at the tip, where they are thought to perform roles in host sensing (9)(10)(11)(12)(13). Activation of the T3SS by host cells results in the secretion of two hydrophobic proteins, which, probably from the tip of the needle, insert directly into the eukaryotic membrane to form an apparatus known as the translocon (13).…”

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confidence: 99%

What's the point of the type III secretion system needle?

Blocker

Deane

Veenendaal

et al. 2008

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

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Recent work by several groups has significantly expanded our knowledge of the structure, regulation of assembly, and function of components of the extracellular portion of the type III secretion system (T3SS) of Gram-negative bacteria. This perspective presents a structure-informed analysis of functional data and discusses three nonmutually exclusive models of how a key aspect of T3SS biology, the sensing of host cells, may be performed.flagella ͉ structure

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“…It was recently reported that IpaB and IpaD, the translocon proteins of Shigella, can be localized on the bacterial cell surface (Olive et al, 2007;Veenendaal et al, 2007). However, the surface localization of PopB and PopD of Pseudomonas, BopB and BopD of Bordetella, and BipB and BipD of Burkholderia have not yet been characterized.…”

Section: Discussionmentioning

confidence: 99%

“…It has been reported that Shigella IpaB, a homologue of SipB, is associated with the bacterial envelope (Menard et al, 1994;Mills et al, 1988;Watarai et al, 1995) and can be localized to the Shigella cell surface in the presence of T3SS (Olive et al, 2007). Recently, Johnson et al (2006) have shown that surface localization of IpaB is dependent on the presence of IpaD.…”

Section: Introductionmentioning

confidence: 99%

N-terminal residues of SipB are required for its surface localization on Salmonella enterica serovar Typhimurium

Kim

et al. 2008

Microbiology

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Bile Salts Stimulate Recruitment of IpaB to the Shigella flexneri Surface, Where It Colocalizes with IpaD at the Tip of the Type III Secretion Needle

Cited by 124 publications

References 14 publications

Oligomeric states of the Shigella translocator protein IpaB provide structural insights into formation of the type III secretion translocon

Oligomeric states of the Shigella translocator protein IpaB provide structural insights into formation of the type III secretion translocon

What's the point of the type III secretion system needle?

N-terminal residues of SipB are required for its surface localization on Salmonella enterica serovar Typhimurium

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