Characterization of Mce4A protein of Mycobacterium tuberculosis

Role in invasion and survival

Neeraj K. Saini, Monika Sharma, Amita Chandolia, Rashmi Pasricha, Vani Brahmachari, Mridula Bose

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Background. The mce4 operon is one of the four homologues of mammalian cell entry (mce) operons of Mycobacterium tuberculosis. The mce4A (Rv3499c) gene within this operon is homologous to mce1A (Rv0169), that has a role in host cell invasion by M. tuberculosis. Our earlier reports show that mce4 operon is expressed during the stationary phase of growth of the bacillus in culture and during the course of infection in mammalian hosts. M. tuberculosis carrying mutation in mce4 operon shows growth defect and reduced survival in infected mice. However, the intracellular localization of Mce4A protein and its direct role in cell entry or survival of the bacillus has not been demonstrated so far. Results. By transmission electron microscopy we have demonstrated that recombinant Mce4A protein facilitates the invasion of non-pathogenic strain of E. coli into non-phagocytic HeLa cells. We observe that mce4A gene has a role comparable to mce1A in the survival of recombinant E. coli in human macrophages. Using antibodies raised against Mce4A protein, we show that the protein is localized in the cell wall fraction of M. tuberculosis H37Rv stationary phase culture only. Conclusion. Mce4A protein is expressed during the stationary phase of broth culture and localizes in the cell wall fraction of M. tuberculosis. Mce4A protein expressed in non-pathogenic E. coli enables it to enter and survive within HeLa cells and the macrophages. As Mce4A protein is expressed during later phase of mycobacterial growth, our results raise the possibility of it playing a role in maintenance of persistent tubercular infection.

Original languageEnglish (US)
Article number200
JournalBMC Microbiology
Volume8
DOIs
StatePublished - 2008
Externally publishedYes

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Operon
Mycobacterium tuberculosis
Survival
Proteins
Escherichia coli
HeLa Cells
Cell Wall
Bacillus
Growth
Macrophages
Infection
Transmission Electron Microscopy
Recombinant Proteins
Genes
Mycobacterium tuberculosis Mce4A protein
Maintenance
Mutation
Antibodies

ASJC Scopus subject areas

  • Microbiology (medical)
  • Microbiology

Cite this

Characterization of Mce4A protein of Mycobacterium tuberculosis : Role in invasion and survival. / Saini, Neeraj K.; Sharma, Monika; Chandolia, Amita; Pasricha, Rashmi; Brahmachari, Vani; Bose, Mridula.

In: BMC Microbiology, Vol. 8, 200, 2008.

Research output: Contribution to journalArticle

Saini, Neeraj K. ; Sharma, Monika ; Chandolia, Amita ; Pasricha, Rashmi ; Brahmachari, Vani ; Bose, Mridula. / Characterization of Mce4A protein of Mycobacterium tuberculosis : Role in invasion and survival. In: BMC Microbiology. 2008 ; Vol. 8.
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abstract = "Background. The mce4 operon is one of the four homologues of mammalian cell entry (mce) operons of Mycobacterium tuberculosis. The mce4A (Rv3499c) gene within this operon is homologous to mce1A (Rv0169), that has a role in host cell invasion by M. tuberculosis. Our earlier reports show that mce4 operon is expressed during the stationary phase of growth of the bacillus in culture and during the course of infection in mammalian hosts. M. tuberculosis carrying mutation in mce4 operon shows growth defect and reduced survival in infected mice. However, the intracellular localization of Mce4A protein and its direct role in cell entry or survival of the bacillus has not been demonstrated so far. Results. By transmission electron microscopy we have demonstrated that recombinant Mce4A protein facilitates the invasion of non-pathogenic strain of E. coli into non-phagocytic HeLa cells. We observe that mce4A gene has a role comparable to mce1A in the survival of recombinant E. coli in human macrophages. Using antibodies raised against Mce4A protein, we show that the protein is localized in the cell wall fraction of M. tuberculosis H37Rv stationary phase culture only. Conclusion. Mce4A protein is expressed during the stationary phase of broth culture and localizes in the cell wall fraction of M. tuberculosis. Mce4A protein expressed in non-pathogenic E. coli enables it to enter and survive within HeLa cells and the macrophages. As Mce4A protein is expressed during later phase of mycobacterial growth, our results raise the possibility of it playing a role in maintenance of persistent tubercular infection.",
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