Recently, a novel type of secretory pathway, type VII secretion systems (T7SSs), has been characterized in mycobacteria. The chromosomes of Mycobacterium tuberculosis and Mycobacterium bovis encode five T7SSs (ESX-1 to ESX-5). The best characterized of them, ESX-1, is involved in host-pathogen interactions, and its deletion is one of the main causes of M. bovis BCG attenuation. Another T7SS, ESX-3, has been previously shown to be transcriptionally controlled by the zinc uptake repressor (Zur) and by the iron-dependent transcriptional repressor (IdeR), suggesting that it might be involved in zinc and iron homeostasis. In this study, we characterized an M. tuberculosis conditional mutant in which transcription of the ESX-3 gene cluster can be downregulated by anhydrotetracycline. We showed that this T7SS is essential for growth and that this phenotype can be complemented by zinc, iron, or supernatant from a wild-type parental strain culture, demonstrating that the ESX-3 secretion system is responsible for the secretion of some soluble factor(s) required for growth that is probably involved in optimal iron and zinc uptake.

Characterization of a Mycobacterium tuberculosis ESX-3 Conditional Mutant: Essentiality and Rescue by Iron and Zinc

SERAFINI, AGNESE;BOLDRIN, FRANCESCA;PALU', GIORGIO;MANGANELLI, RICCARDO
2009

Abstract

Recently, a novel type of secretory pathway, type VII secretion systems (T7SSs), has been characterized in mycobacteria. The chromosomes of Mycobacterium tuberculosis and Mycobacterium bovis encode five T7SSs (ESX-1 to ESX-5). The best characterized of them, ESX-1, is involved in host-pathogen interactions, and its deletion is one of the main causes of M. bovis BCG attenuation. Another T7SS, ESX-3, has been previously shown to be transcriptionally controlled by the zinc uptake repressor (Zur) and by the iron-dependent transcriptional repressor (IdeR), suggesting that it might be involved in zinc and iron homeostasis. In this study, we characterized an M. tuberculosis conditional mutant in which transcription of the ESX-3 gene cluster can be downregulated by anhydrotetracycline. We showed that this T7SS is essential for growth and that this phenotype can be complemented by zinc, iron, or supernatant from a wild-type parental strain culture, demonstrating that the ESX-3 secretion system is responsible for the secretion of some soluble factor(s) required for growth that is probably involved in optimal iron and zinc uptake.
2009
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2448211
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 159
  • ???jsp.display-item.citation.isi??? 139
social impact