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J Cell Sci. 2019 May 2;132(9). pii: jcs226217. doi: 10.1242/jcs.226217.

Shigella MreB promotes polar IcsA positioning for actin tail formation.

Author information

1
Section of Microbiology, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Road, London SW7 2AZ, UK.
2
Department of Immunology & Infection, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK.
3
Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7JT, UK.
4
Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400 PHRI 07103, Thailand.
5
Public Health Research Institute, Rutgers Biomedical and Health Science, Newark, New Jersey NJ 07103, USA.
6
MICALIS Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
7
Section of Microbiology, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Road, London SW7 2AZ, UK serge.mostowy@lshtm.ac.uk.

Abstract

Pathogenic Shigella bacteria are a paradigm to address key issues of cell and infection biology. Polar localisation of the Shigella autotransporter protein IcsA is essential for actin tail formation, which is necessary for the bacterium to travel from cell-to-cell; yet how proteins are targeted to the bacterial cell pole is poorly understood. The bacterial actin homologue MreB has been extensively studied in broth culture using model organisms including Escherichia coli, Bacillus subtilis and Caulobacter crescentus, but has never been visualised in rod-shaped pathogenic bacteria during infection of host cells. Here, using single-cell analysis of intracellular Shigella, we discover that MreB accumulates at the cell pole of bacteria forming actin tails, where it colocalises with IcsA. Pharmacological inhibition of host cell actin polymerisation and genetic deletion of IcsA is used to show, respectively, that localisation of MreB to the cell poles precedes actin tail formation and polar localisation of IcsA. Finally, by exploiting the MreB inhibitors A22 and MP265, we demonstrate that MreB polymerisation can support actin tail formation. We conclude that Shigella MreB promotes polar IcsA positioning for actin tail formation, and suggest that understanding the bacterial cytoskeleton during host-pathogen interactions can inspire development of new therapeutic regimes for infection control.This article has an associated First Person interview with the first author of the paper.

KEYWORDS:

Actin; IcsA; MreB; Septin; Shigella

PMID:
30992346
DOI:
10.1242/jcs.226217
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Conflict of interest statement

Competing interestsThe authors declare no competing or financial interests.

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