WhiB4 Regulates the PE/PPE Gene Family and is Essential for Virulence of Mycobacterium marinum

Abstract

During the course of infection, pathogenic mycobacteria including Mycobacterium tuberculosis (M. tb) encounter host environments of variable oxygen tension, ranging from the hypoxic center of granulomas to the most oxygenated region in the lung cavities. Mycobacterial responses to changes of oxygen tension are critically related to infection outcomes, such as latency and reactivation. WhiB4 is an iron-sulfur containing transcription factor that is highly sensitive to oxygen exposure. In this study, we found that WhiB4 of Mycobacterium marinum (M. marinum), a pathogenic mycobacterial species that is closely related to M. tb, is required for its virulence. M. marinum ΔwhiB4 exhibited defective intracellular replication in macrophages and diminished virulence in zebrafish. Histology analysis revealed that the host had successfully controlled ΔwhiB4 bacteria, forming well-organized granulomas. RNA-seq analysis identified a large number of pe/ppe genes that were regulated by WhiB4, which provides an explanation for the essential role of WhiB4 in M. marinum virulence. Several antioxidant enzymes were also upregulated in ΔwhiB4, supporting its role in modulation of oxidative stress response. Taken together, we have provided new insight into and proposed a model to explain the physiological role of WhiB4.

DistinctMycobacterium marinumphosphatases determine pathogen vacuole phosphoinositide pattern, phagosome maturation, and escape to the cytosol

“…In any case and in agreement with reported growth characteristics, M . marinum replicated more efficiently in RAW 264.7 macrophages at 30°C compared with 37°C (Figures b and S4b; Lerena & Colombo, ; Wu et al, ). Of note, RAW 264.7 cells are derived from BALB/c mice that have a defective Nramp1 gene (Vidal, Pinner, Lepage, Gauthier, & Gros, ).…”

Transcriptome Changes of Mycobacterium marinum in the Process of Resuscitation From Hypoxia-Induced Dormancy

“…Rv0081 plays an important role connecting the early and enduring hypoxic responses (Sun et al, 2018). WhiB4 (MMAR_5170) is an oxygen-sensitive transcription factor and has been shown to regulate PE/PPE family proteins, and it plays a role in M. marinum virulence (Chawla et al, 2012;Wu et al, 2017). CosR (MMAR_4874) is a copper-inducible transcriptional regulator, and the loss of cosR resulted in a hypoxia-type response with the induction of the DosR regulon (Talaat et al, 2004;Ward et al, 2008;Marcus et al, 2016).…”

“…The frozen cell pellets were resuspended in 1 mL TRIzol reagent (CW Bio). RNA extraction and illumina sequencing were performed as previously described (Wu et al, 2017). Raw data of RNA sequencing have been uploaded to the GEO database (BioProject ID : PRJNA588556).…”

When Dicty Met Myco, a (Not So) Romantic Story about One Amoeba and Its Intracellular Pathogen

“…This method has been used to describe the gene expression profile of M. marinum during exponential and stationary growth (Wang et al, 2013 ), as well as under stress conditions (Pettersson et al, 2015 ). In addition, it has allowed to determine the contribution of specific cells (neutrophils and macrophages) to the innate immune response against M. marinum , Mtb, and M. bovis (Schnappinger et al, 2003 ; Nalpas et al, 2015 ; Kenyon et al, 2017 ) and to identify genes such as whiB4 , which encodes a protein regulating the PE/PPE genes and is required for M. marinum and Mtb virulence (Chawla et al, 2012 ; Wu et al, 2017 ). Moreover, a recent metabolomics study coupled to dual RNA-Seq allowed to reconstruct the dietary map of Mtb during macrophage infection (Zimmermann et al, 2017 ).…”