The secretion of the Shigella flexneri Ipa invasins is activated by epithelial cells and controlled by IpaB and IpaD.

Ménard, Robert; Sansonetti, Philippe J.; Parsot, Claude

doi:10.1002/j.1460-2075.1994.tb06863.x

Cited by 347 publications

(388 citation statements)

References 36 publications

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“…During growth of bacteria in broth at 37 u C, the TTS apparatus is assembled in the bacterial envelope but is only weakly active (Menard et al, 1994a) and substrates of the TTS apparatus are stored in the cytoplasm in association with specific chaperones (Menard et al, 1994b; Niebuhr et al, 2000;Ogawa et al, 2003; Page et al, 2001Page et al, , 2002. The TTS apparatus is activated upon both contact of bacteria with epithelial cells (Menard et al, 1994a) et al, 1989) and transcription of an icsA-lacZ fusion carried by a reporter plasmid was decreased 2?5-fold in a virF mutant compared with the wild-type strain (Sakai et al, 1988), suggesting that expression of icsA was directly under the control of VirF. Northern blot analysis indicated that expression of icsA was moderately (2-fold) modulated by the temperature of growth (Porter & Dorman, 1997).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…The TTS apparatus is deregulated, i.e. constitutively active in bacteria growing in broth, by inactivation of ipaB or ipaD (Menard et al, 1994a). Conditions of active or deregulated secretion lead to increased transcription of members of the ipaH family, ospF, virA and ospC1, but not genes of the entry region (Demers et al, 1998;Mavris et al, 2002a).…”

Section: Introductionmentioning

confidence: 99%

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Analysis of virulence plasmid gene expression defines three classes of effectors in the type III secretion system of Shigella flexneri

Gall

Mavris

Martino³

et al. 2005

Microbiology

115

174

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Proteins directly involved in entry and dissemination of Shigella flexneri into epithelial cells are encoded by a virulence plasmid of 200 kb. A 30-kb region (designated the entry region) of this plasmid encodes components of a type III secretion (TTS) apparatus, substrates of this apparatus and their dedicated chaperones. During growth of bacteria in broth, expression of these genes is induced at 37 6C and the TTS apparatus is assembled in the bacterial envelope but is not active. Secretion is activated upon contact of bacteria with host cells and is deregulated in an ipaB mutant. The plasmid encodes four transcriptional regulators, VirF, VirB, MxiE and Orf81. VirF controls transcription of virB, whose product is required for transcription of entry region genes. MxiE, with the chaperone IpgC acting as a co-activator, controls expression of several effectors that are induced under conditions of secretion. Genes under the control of Orf81 are not known. The aim of this study was to define further the repertoires of virulence plasmid genes that are under the control of (i) the growth temperature, (ii) each of the known virulence plasmid-encoded transcriptional regulators (VirF, VirB, MxiE and Orf81) and (iii) the activity of the TTS apparatus. Using a macroarray analysis, the expression profiles of 71 plasmid genes were compared in the wild-type strain grown at 37 and 30 6C and in virF, virB, mxiE, ipaB, ipaB mxiE and orf81 mutants grown at 37 6C. Many genes were found to be under the control of VirB and indirectly of VirF. No alteration of expression of any gene was detected in the orf81 mutant. Expression of 13 genes was increased in the secretion-deregulated ipaB mutant in an MxiE-dependent manner. On the basis of their expression profile, substrates of the TTS apparatus can be classified into three categories: (i) those that are controlled by VirB, (ii) those that are controlled by MxiE and (iii) those that are controlled by both VirB and MxiE. The differential regulation of expression of TTS effectors in response to the TTS apparatus activity suggests that different effectors might be required at different times following contact of bacteria with host cells. INTRODUCTIONBacteria of Shigella species are responsible for shigellosis, a human disease characterized by the destruction of the colonic epithelium. Shigellae and enteroinvasive Escherichia coli both contain a virulence plasmid (VP) of approximately 200 kb that encodes most proteins directly involved in entry and dissemination of bacteria into epithelial cells. Sequence analysis of the VP pWR100 (Buchrieser et al., 2000) and its derivative pWR501 (Venkatesan et al., 2001) from a Shigella flexneri strain of serotype 5 and the VP pCP301 (Jin et al., 2002) from an S. flexneri strain of serotype 2a indicated that the VP is composed of a mosaic of approximately 100 genes and numerous insertion sequences. The VP genes exhibit a G+C content from 30 to 60 mol%, suggesting that they were acquired from different sources. The current model of the TTS pathway prop...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Analysis of virulence plasmid gene expression defines three classes of effectors in the type III secretion system of Shigella flexneri

Gall

Mavris

Martino³

et al. 2005

Microbiology

115

174

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“…Although Ipa sequences do not contain classical signal peptide sequences (4,7), the IpaB, IpaC, and IpaD proteins can be secreted onto the bacterial surface and released into the external medium, but only when the Mxi and Spa functions are expressed (1,2,6,8,9). Release of Ipa proteins into the external medium is triggered upon contact of the bacterium with the epithehal cells (10)(11)(12), and the released Ipa proteins form high molecular matrix structures (13).…”

mentioning

confidence: 99%

Interaction of Ipa proteins of Shigella flexneri with alpha5beta1 integrin promotes entry of the bacteria into mammalian cells.

Watarai

Funato

Sasakawa

1996

The Journal of Experimental Medicine

218

145

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SummaryShigella is a genus of highly adapted bacterial pathogens that cause bacillary dysentery in humans.Bacteria reaching the colon invade intestinal epithehal cells by a process of bacterial-directed endocytosis mediated by the Ipa proteins: IpaB, IpaC, and IpaD of Shigella. The invasion of epithelial cells is thought to be a receptor-mediated phenomenon, although the cellular components of the host that interact with the Ipa proteins have not yet been identified. We report here that in a Shigellaflexneri invasive system and Chinese hamster ovary (CHO) cell monolayers, the Ipa proteins were capable of interacting directly with oL5131 integrin. The invasive capacity of S. flexneri for CHO cells increased as levels of cx5131 integrin were elevated. When CHO cells were infected with S. flexneri, the tyrosine phosphorylation both ofpp 125 F~, an integrin-regulated 125 K focal adhesion kinase, and of paxillin was stimulated. In contrast, an isogenic strain of S. flexneri that was defective in invasion owing to a mutation in its spa32 gene failed to induce such phosphorylation. Under in vitro and in vivo conditions, the released IpaB, IpaC, and IpaD proteins bound to ot5[~ 1 integrin in a manner different from that of soluble fibronectin but similar to that of the tissue form of fibronectin. At the site of attachment of S. flexneri to CHO cells, ot5131 integrin converged with polymerization of actin. These data thus suggest that the capacity oflpa proteins to interact with o~5151 integrin may be an important Shigella factor in triggering the reorganization of actin cytoskeletons.

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“…A maioria dessas funções está relacionada a proteínas codificadas por um fragmento de 31Kb do plasmídio de virulência formado por 38 genes. Entre esses genes estão ipaA, ipaB, ipaC, ipaD (responsáveis pela invasão, sobrevivência intracelular e escape bacteriano) VENKATESAN & BUYSSE, 1990;MENARD et al, 1993;MENARD et al, 1994a), ipgC (chaperona responsável pela estabilidade de ipaB e ipaC) (MENARD et al, 1994b), virB (proteína responsável para transcrição dos genes ipa e mxi-spa) , icsA, icsB (responsáveis pela disseminação celular e inibição da autofagia) (MAKINO et al, 1986;BERNARDINI et al, 1989;OGAWA et al, 2005), ospC1, ospF, ospG (responsáveis pela regulação da resposta imune do hospedeiro) (ZURAWSKI et al, 2006;KIM et al, 2008) e os genes do lócus mxi-spa (responsáveis pelo aparato do sistema de secreção do tipo III) (VENKATESAN et al, 1992;SASAKAWA et al, 1993;RATHMAN et al, 2000). O contato da bactéria com a superfície celular do hospedeiro induz à secreção dessas proteínas efetoras no interior de células hospedeiras, essenciais na sobrevivência bacteriana na célula do hospedeiro, conduzidas pelo sistema de secreção do tipo III (COSSART & SANSONETTI, 2004).…”

Section: E Coli Enteroinvasora (Eiec) E Coli Enteropatogênica (Epeunclassified

O papel da flagelina e do sistema de secreção de Escherichia coli enteroinvasora na resposta imune inata dos macrófagos

Ferreira¹

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The secretion of the Shigella flexneri Ipa invasins is activated by epithelial cells and controlled by IpaB and IpaD.

Cited by 347 publications

References 36 publications

Analysis of virulence plasmid gene expression defines three classes of effectors in the type III secretion system of Shigella flexneri

Analysis of virulence plasmid gene expression defines three classes of effectors in the type III secretion system of Shigella flexneri

Interaction of Ipa proteins of Shigella flexneri with alpha5beta1 integrin promotes entry of the bacteria into mammalian cells.

O papel da flagelina e do sistema de secreção de Escherichia coli enteroinvasora na resposta imune inata dos macrófagos

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