Structure-Function Analysis of DipA, a Francisella tularensis Virulence Factor Required for Intracellular Replication.

Francisella tularensis is a highly infectious bacterium whose virulence relies on its ability to rapidly reach the macrophage cytosol and extensively replicate in this compartment. We previously identified a novel Francisella virulence factor, DipA (FTT0369c), which is required for intramacrophage p...

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Main Authors: Audrey Chong, Robert Child, Tara D Wehrly, Dedeke Rockx-Brouwer, Aiping Qin, Barbara J Mann, Jean Celli
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2013-01-01
Series:PLoS ONE
Online Access:https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0067965&type=printable
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author Audrey Chong
Robert Child
Tara D Wehrly
Dedeke Rockx-Brouwer
Aiping Qin
Barbara J Mann
Jean Celli
author_facet Audrey Chong
Robert Child
Tara D Wehrly
Dedeke Rockx-Brouwer
Aiping Qin
Barbara J Mann
Jean Celli
author_sort Audrey Chong
collection DOAJ
description Francisella tularensis is a highly infectious bacterium whose virulence relies on its ability to rapidly reach the macrophage cytosol and extensively replicate in this compartment. We previously identified a novel Francisella virulence factor, DipA (FTT0369c), which is required for intramacrophage proliferation and survival, and virulence in mice. DipA is a 353 amino acid protein with a Sec-dependent signal peptide, four Sel1-like repeats (SLR), and a C-terminal coiled-coil (CC) domain. Here, we determined through biochemical and localization studies that DipA is a membrane-associated protein exposed on the surface of the prototypical F. tularensis subsp. tularensis strain SchuS4 during macrophage infection. Deletion and substitution mutagenesis showed that the CC domain, but not the SLR motifs, of DipA is required for surface exposure on SchuS4. Complementation of the dipA mutant with either DipA CC or SLR domain mutants did not restore intracellular growth of Francisella, indicating that proper localization and the SLR domains are required for DipA function. Co-immunoprecipitation studies revealed interactions with the Francisella outer membrane protein FopA, suggesting that DipA is part of a membrane-associated complex. Altogether, our findings indicate that DipA is positioned at the host-pathogen interface to influence the intracellular fate of this pathogen.
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spelling doaj-art-5cab4600db4a4ef19ec4c01080f2108b2025-08-20T02:30:38ZengPublic Library of Science (PLoS)PLoS ONE1932-62032013-01-0186e6796510.1371/journal.pone.0067965Structure-Function Analysis of DipA, a Francisella tularensis Virulence Factor Required for Intracellular Replication.Audrey ChongRobert ChildTara D WehrlyDedeke Rockx-BrouwerAiping QinBarbara J MannJean CelliFrancisella tularensis is a highly infectious bacterium whose virulence relies on its ability to rapidly reach the macrophage cytosol and extensively replicate in this compartment. We previously identified a novel Francisella virulence factor, DipA (FTT0369c), which is required for intramacrophage proliferation and survival, and virulence in mice. DipA is a 353 amino acid protein with a Sec-dependent signal peptide, four Sel1-like repeats (SLR), and a C-terminal coiled-coil (CC) domain. Here, we determined through biochemical and localization studies that DipA is a membrane-associated protein exposed on the surface of the prototypical F. tularensis subsp. tularensis strain SchuS4 during macrophage infection. Deletion and substitution mutagenesis showed that the CC domain, but not the SLR motifs, of DipA is required for surface exposure on SchuS4. Complementation of the dipA mutant with either DipA CC or SLR domain mutants did not restore intracellular growth of Francisella, indicating that proper localization and the SLR domains are required for DipA function. Co-immunoprecipitation studies revealed interactions with the Francisella outer membrane protein FopA, suggesting that DipA is part of a membrane-associated complex. Altogether, our findings indicate that DipA is positioned at the host-pathogen interface to influence the intracellular fate of this pathogen.https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0067965&type=printable
spellingShingle Audrey Chong
Robert Child
Tara D Wehrly
Dedeke Rockx-Brouwer
Aiping Qin
Barbara J Mann
Jean Celli
Structure-Function Analysis of DipA, a Francisella tularensis Virulence Factor Required for Intracellular Replication.
PLoS ONE
title Structure-Function Analysis of DipA, a Francisella tularensis Virulence Factor Required for Intracellular Replication.
title_full Structure-Function Analysis of DipA, a Francisella tularensis Virulence Factor Required for Intracellular Replication.
title_fullStr Structure-Function Analysis of DipA, a Francisella tularensis Virulence Factor Required for Intracellular Replication.
title_full_unstemmed Structure-Function Analysis of DipA, a Francisella tularensis Virulence Factor Required for Intracellular Replication.
title_short Structure-Function Analysis of DipA, a Francisella tularensis Virulence Factor Required for Intracellular Replication.
title_sort structure function analysis of dipa a francisella tularensis virulence factor required for intracellular replication
url https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0067965&type=printable
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