<named-content content-type="genus-species">Shigella flexneri</named-content> Regulation of ARF6 Activation during Bacterial Entry via an IpgD-Mediated Positive Feedback Loop

ABSTRACT Entry into cells is critical for virulence of the human bacterial pathogens Shigella spp. Shigella spp. induce membrane ruffle formation and macropinocytic uptake, but the events instigating this process are incompletely understood. The host small GTPase ADP-ribosylation factor 6 (ARF6) fun...

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Autores principales:	Anna Cristina Garza-Mayers, Kelly A. Miller, Brian C. Russo, Dipal V. Nagda, Marcia B. Goldberg
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2015
Materias:	Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/17f59298da66440791a4ba048c7b7f4b
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spelling	oai:doaj.org-article:17f59298da66440791a4ba048c7b7f4b2021-11-15T15:41:33Z<named-content content-type="genus-species">Shigella flexneri</named-content> Regulation of ARF6 Activation during Bacterial Entry via an IpgD-Mediated Positive Feedback Loop10.1128/mBio.02584-142150-7511https://doaj.org/article/17f59298da66440791a4ba048c7b7f4b2015-05-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.02584-14https://doaj.org/toc/2150-7511ABSTRACT Entry into cells is critical for virulence of the human bacterial pathogens Shigella spp. Shigella spp. induce membrane ruffle formation and macropinocytic uptake, but the events instigating this process are incompletely understood. The host small GTPase ADP-ribosylation factor 6 (ARF6) functions in membrane trafficking at the plasma membrane and activates membrane ruffle formation. We demonstrate that ARF6 is required for efficient Shigella flexneri entry, is activated by S. flexneri dependent on the phosphatase activity of the type III secreted effector IpgD, and depends on cytohesin guanine nucleotide exchange factors (GEFs) for recruitment to entry sites. The cytohesin GEF ARF nucleotide binding site opener (ARNO) is recruited to these sites, also dependent on IpgD phosphatase activity. ARNO recruitment is independent of ARF6, indicating that, in addition to the described recruitment of ARNO by ARF6, ARNO is recruited upstream of ARF6. Our data provide evidence that ARF6, IpgD, phosphoinositide species, and ARNO constitute a previously undescribed positive feedback loop that amplifies ARF6 activation at bacterial entry sites, thereby promoting efficient S. flexneri uptake. IMPORTANCE Shigella spp. cause diarrhea and dysentery by infection of epithelial cells in the human colon. Critical to disease is the ability of Shigella to enter into cells, yet the mechanisms involved in entry are incompletely understood. We demonstrate that the small GTPase ADP-ribosylation factor 6 (ARF6) is required for efficient cellular entry of Shigella flexneri and that activation of ARF6 depends on the phosphatase activity of the Shigella protein IpgD, which is introduced into cells via the bacterial type III secretion system. We further show that IpgD phosphatase activity is required for recruitment of the ARF6 guanine nucleotide exchange factor (GEF) ARF nucleotide binding site opener (ARNO) to bacterial entry sites and that ARNO lies upstream of ARF6 activation. These relationships define a positive feedback loop that contributes to activation of ARF6 at S. flexneri entry sites and leads to local amplification of signals that promote bacterial entry.Anna Cristina Garza-MayersKelly A. MillerBrian C. RussoDipal V. NagdaMarcia B. GoldbergAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 6, Iss 2 (2015)
institution	DOAJ
collection	DOAJ
language	EN
topic	Microbiology QR1-502
spellingShingle	Microbiology QR1-502 Anna Cristina Garza-Mayers Kelly A. Miller Brian C. Russo Dipal V. Nagda Marcia B. Goldberg <named-content content-type="genus-species">Shigella flexneri</named-content> Regulation of ARF6 Activation during Bacterial Entry via an IpgD-Mediated Positive Feedback Loop
description	ABSTRACT Entry into cells is critical for virulence of the human bacterial pathogens Shigella spp. Shigella spp. induce membrane ruffle formation and macropinocytic uptake, but the events instigating this process are incompletely understood. The host small GTPase ADP-ribosylation factor 6 (ARF6) functions in membrane trafficking at the plasma membrane and activates membrane ruffle formation. We demonstrate that ARF6 is required for efficient Shigella flexneri entry, is activated by S. flexneri dependent on the phosphatase activity of the type III secreted effector IpgD, and depends on cytohesin guanine nucleotide exchange factors (GEFs) for recruitment to entry sites. The cytohesin GEF ARF nucleotide binding site opener (ARNO) is recruited to these sites, also dependent on IpgD phosphatase activity. ARNO recruitment is independent of ARF6, indicating that, in addition to the described recruitment of ARNO by ARF6, ARNO is recruited upstream of ARF6. Our data provide evidence that ARF6, IpgD, phosphoinositide species, and ARNO constitute a previously undescribed positive feedback loop that amplifies ARF6 activation at bacterial entry sites, thereby promoting efficient S. flexneri uptake. IMPORTANCE Shigella spp. cause diarrhea and dysentery by infection of epithelial cells in the human colon. Critical to disease is the ability of Shigella to enter into cells, yet the mechanisms involved in entry are incompletely understood. We demonstrate that the small GTPase ADP-ribosylation factor 6 (ARF6) is required for efficient cellular entry of Shigella flexneri and that activation of ARF6 depends on the phosphatase activity of the Shigella protein IpgD, which is introduced into cells via the bacterial type III secretion system. We further show that IpgD phosphatase activity is required for recruitment of the ARF6 guanine nucleotide exchange factor (GEF) ARF nucleotide binding site opener (ARNO) to bacterial entry sites and that ARNO lies upstream of ARF6 activation. These relationships define a positive feedback loop that contributes to activation of ARF6 at S. flexneri entry sites and leads to local amplification of signals that promote bacterial entry.
format	article
author	Anna Cristina Garza-Mayers Kelly A. Miller Brian C. Russo Dipal V. Nagda Marcia B. Goldberg
author_facet	Anna Cristina Garza-Mayers Kelly A. Miller Brian C. Russo Dipal V. Nagda Marcia B. Goldberg
author_sort	Anna Cristina Garza-Mayers
title	<named-content content-type="genus-species">Shigella flexneri</named-content> Regulation of ARF6 Activation during Bacterial Entry via an IpgD-Mediated Positive Feedback Loop
title_short	<named-content content-type="genus-species">Shigella flexneri</named-content> Regulation of ARF6 Activation during Bacterial Entry via an IpgD-Mediated Positive Feedback Loop
title_full	<named-content content-type="genus-species">Shigella flexneri</named-content> Regulation of ARF6 Activation during Bacterial Entry via an IpgD-Mediated Positive Feedback Loop
title_fullStr	<named-content content-type="genus-species">Shigella flexneri</named-content> Regulation of ARF6 Activation during Bacterial Entry via an IpgD-Mediated Positive Feedback Loop
title_full_unstemmed	<named-content content-type="genus-species">Shigella flexneri</named-content> Regulation of ARF6 Activation during Bacterial Entry via an IpgD-Mediated Positive Feedback Loop
title_sort	<named-content content-type="genus-species">shigella flexneri</named-content> regulation of arf6 activation during bacterial entry via an ipgd-mediated positive feedback loop
publisher	American Society for Microbiology
publishDate	2015
url	https://doaj.org/article/17f59298da66440791a4ba048c7b7f4b
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<named-content content-type="genus-species">Shigella flexneri</named-content> Regulation of ARF6 Activation during Bacterial Entry via an IpgD-Mediated Positive Feedback Loop

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