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PhoP: a missing piece in the intricate puzzle of Mycobacterium tuberculosis virulence.

Gonzalo-Asensio J, Mostowy S, Harders-Westerveen J, Huygen K, Hernández-Pando R, Thole J, Behr M, Gicquel B, Martín C - PLoS ONE (2008)

Bottom Line: Inactivation of the transcriptional regulator PhoP results in Mycobacterium tuberculosis attenuation.Preclinical testing has shown that attenuated M. tuberculosis phoP mutants hold promise as safe and effective live vaccine candidates.We focused this study to decipher the virulence networks regulated by PhoP.

View Article: PubMed Central - PubMed

Affiliation: Grupo de Genética de Micobacterias, Departamento de Microbiología, Facultad de Medicina, Universidad de Zaragoza, Zaragoza, Spain.

ABSTRACT
Inactivation of the transcriptional regulator PhoP results in Mycobacterium tuberculosis attenuation. Preclinical testing has shown that attenuated M. tuberculosis phoP mutants hold promise as safe and effective live vaccine candidates. We focused this study to decipher the virulence networks regulated by PhoP. A combined transcriptomic and proteomic analysis revealed that PhoP controls a variety of functions including: hypoxia response through DosR crosstalking, respiratory metabolism, secretion of the major T-cell antigen ESAT-6, stress response, synthesis of pathogenic lipids and the M. tuberculosis persistence through transcriptional regulation of the enzyme isocitrate lyase. We also demonstrate that the M. tuberculosis phoP mutant SO2 exhibits an antigenic capacity similar to that of the BCG vaccine. Finally, we provide evidence that the SO2 mutant persists better in mouse organs than BCG. Altogether, these findings indicate that PhoP orchestrates a variety of functions implicated in M. tuberculosis virulence and persistence, making phoP mutants promising vaccine candidates.

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Related in: MedlinePlus

The M. tuberculosis PhoP regulon.The PhoP regulon was identified by comparing transcriptional profiles of the M. tuberculosis wild type and the phoP mutant using DNA microarrays. Some of the more relevant genes to virulence and intracellular survival are listed and grouped by function. Green and red arrows indicate genes whose expression is positively or negatively regulated by PhoP, respectively.
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pone-0003496-g001: The M. tuberculosis PhoP regulon.The PhoP regulon was identified by comparing transcriptional profiles of the M. tuberculosis wild type and the phoP mutant using DNA microarrays. Some of the more relevant genes to virulence and intracellular survival are listed and grouped by function. Green and red arrows indicate genes whose expression is positively or negatively regulated by PhoP, respectively.

Mentions: In a global approach to characterize the PhoP regulon we compared the transcriptome of an M. tuberculosis clinical isolate with its phoP mutant [16]. Seventy-eight genes - approximately 2% of the coding capacity of the M. tuberculosis genome - showed significant differences between both strains (Table S1). In our transcriptomic analysis, the phoP gene itself appears downregulated in the mutant; this serves as an excellent internal control and provides confidence in the results. Additionally, down-regulation of the adjacent phoR gene strongly supports our previous observations that both genes are transcribed in an operon [17]. Genes positively regulated by PhoP include those required for hypoxia adaptation, genes involved in aerobic/anaerobic respiration, genes within the Region of Difference 1 (RD1), genes encoding stress proteins and genes involved in lipid metabolism. Amongst the few genes negatively regulated by PhoP, we found the icl-fadB2-umaA1 operon (Figure 1). In a complementary approach to identify genes regulated by PhoP we compared the protein expression patterns of the wild type strain and the phoP mutant. Analysis from two sets of 2D electrophoresis gels revealed that ICL, EspB - an antigenic protein encoded in the extended RD1 (extRD1) region - and stress proteins such as Hsp65 (GroEL2) and alpha crystallin (HspX or Acr) are differentially expressed between both strains. In agreement with the microarray data, alpha crystallin, EspB, and Hsp65 gave higher expression in the wild type whereas ICL gave higher expression in the phoP mutant (Figure 2 and Table S2). Remarkably, a number of PhoP regulated genes have been previously shown to be differentially expressed upon M. tuberculosis infection of macrophages and dendritic cells (Table S1). These findings point at PhoP as a regulator of key functions for intracellular survival in M. tuberculosis.


PhoP: a missing piece in the intricate puzzle of Mycobacterium tuberculosis virulence.

Gonzalo-Asensio J, Mostowy S, Harders-Westerveen J, Huygen K, Hernández-Pando R, Thole J, Behr M, Gicquel B, Martín C - PLoS ONE (2008)

The M. tuberculosis PhoP regulon.The PhoP regulon was identified by comparing transcriptional profiles of the M. tuberculosis wild type and the phoP mutant using DNA microarrays. Some of the more relevant genes to virulence and intracellular survival are listed and grouped by function. Green and red arrows indicate genes whose expression is positively or negatively regulated by PhoP, respectively.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2566814&req=5

pone-0003496-g001: The M. tuberculosis PhoP regulon.The PhoP regulon was identified by comparing transcriptional profiles of the M. tuberculosis wild type and the phoP mutant using DNA microarrays. Some of the more relevant genes to virulence and intracellular survival are listed and grouped by function. Green and red arrows indicate genes whose expression is positively or negatively regulated by PhoP, respectively.
Mentions: In a global approach to characterize the PhoP regulon we compared the transcriptome of an M. tuberculosis clinical isolate with its phoP mutant [16]. Seventy-eight genes - approximately 2% of the coding capacity of the M. tuberculosis genome - showed significant differences between both strains (Table S1). In our transcriptomic analysis, the phoP gene itself appears downregulated in the mutant; this serves as an excellent internal control and provides confidence in the results. Additionally, down-regulation of the adjacent phoR gene strongly supports our previous observations that both genes are transcribed in an operon [17]. Genes positively regulated by PhoP include those required for hypoxia adaptation, genes involved in aerobic/anaerobic respiration, genes within the Region of Difference 1 (RD1), genes encoding stress proteins and genes involved in lipid metabolism. Amongst the few genes negatively regulated by PhoP, we found the icl-fadB2-umaA1 operon (Figure 1). In a complementary approach to identify genes regulated by PhoP we compared the protein expression patterns of the wild type strain and the phoP mutant. Analysis from two sets of 2D electrophoresis gels revealed that ICL, EspB - an antigenic protein encoded in the extended RD1 (extRD1) region - and stress proteins such as Hsp65 (GroEL2) and alpha crystallin (HspX or Acr) are differentially expressed between both strains. In agreement with the microarray data, alpha crystallin, EspB, and Hsp65 gave higher expression in the wild type whereas ICL gave higher expression in the phoP mutant (Figure 2 and Table S2). Remarkably, a number of PhoP regulated genes have been previously shown to be differentially expressed upon M. tuberculosis infection of macrophages and dendritic cells (Table S1). These findings point at PhoP as a regulator of key functions for intracellular survival in M. tuberculosis.

Bottom Line: Inactivation of the transcriptional regulator PhoP results in Mycobacterium tuberculosis attenuation.Preclinical testing has shown that attenuated M. tuberculosis phoP mutants hold promise as safe and effective live vaccine candidates.We focused this study to decipher the virulence networks regulated by PhoP.

View Article: PubMed Central - PubMed

Affiliation: Grupo de Genética de Micobacterias, Departamento de Microbiología, Facultad de Medicina, Universidad de Zaragoza, Zaragoza, Spain.

ABSTRACT
Inactivation of the transcriptional regulator PhoP results in Mycobacterium tuberculosis attenuation. Preclinical testing has shown that attenuated M. tuberculosis phoP mutants hold promise as safe and effective live vaccine candidates. We focused this study to decipher the virulence networks regulated by PhoP. A combined transcriptomic and proteomic analysis revealed that PhoP controls a variety of functions including: hypoxia response through DosR crosstalking, respiratory metabolism, secretion of the major T-cell antigen ESAT-6, stress response, synthesis of pathogenic lipids and the M. tuberculosis persistence through transcriptional regulation of the enzyme isocitrate lyase. We also demonstrate that the M. tuberculosis phoP mutant SO2 exhibits an antigenic capacity similar to that of the BCG vaccine. Finally, we provide evidence that the SO2 mutant persists better in mouse organs than BCG. Altogether, these findings indicate that PhoP orchestrates a variety of functions implicated in M. tuberculosis virulence and persistence, making phoP mutants promising vaccine candidates.

Show MeSH
Related in: MedlinePlus