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

Audrey Chong; Robert Child; Tara D Wehrly; Dedeke Rockx-Brouwer; Aiping Qin; Barbara J Mann; Jean Celli

doi:10.1371/journal.pone.0067965

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

Journal article

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

Audrey Chong, Robert Child, Tara D Wehrly, Dedeke Rockx-Brouwer, Aiping Qin, Barbara J Mann and Jean Celli

PloS one, Vol.8(6), pp.e67965-e67965

2013

DOI: https://doi.org/10.1371/journal.pone.0067965

Handle:

https://hdl.handle.net/2376/103082

PMCID: PMC3694160

PMID: 23840797

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Abstract

Tularemia - metabolism

Virulence Factors - genetics

Bacterial Proteins - chemistry

Bacterial Proteins - genetics

Cells, Cultured

Structure-Activity Relationship

Virulence Factors - chemistry

Macrophages - metabolism

Tularemia - microbiology

Animals

Bacterial Outer Membrane Proteins - metabolism

Francisella tularensis - growth & development

Tularemia - pathology

Bacterial Proteins - metabolism

Virulence Factors - metabolism

Mice

Mice, Inbred BALB C

Bacterial Outer Membrane Proteins - genetics

Macrophages - microbiology

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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Title: Structure-Function Analysis of DipA, a Francisella tularensis Virulence Factor Required for Intracellular Replication
Creators: Audrey Chong - Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
Robert Child
Tara D Wehrly
Dedeke Rockx-Brouwer
Aiping Qin
Barbara J Mann
Jean Celli
Publication Details: PloS one, Vol.8(6), pp.e67965-e67965
Academic Unit: Paul G. Allen School for Global Animal Health
Publisher: United States
Grant note: Z01 AI000953 / Intramural NIH HHS
Identifiers: 99900546794601842
Language: English
Resource Type: Journal article