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Updated: Apr 21, 2026
Production and Visualization of Bacterial Spheroplasts and Protoplasts to Characterize Antimicrobial Peptide Localization
Published on: August 11, 2018
Impact of protein domains on PE_PGRS30 polar localization in Mycobacteria
Flavio De Maio1, Giuseppe Maulucci2, Mariachiara Minerva1
1Institute of Microbiology, Universita' Cattolica del Sacro Cuore, Rome, Italy.
Abstract:
PE_PGRS proteins are unique to the Mycobacterium tuberculosis complex and a number of other pathogenic mycobacteria. PE_PGRS30, which is required for the full virulence of M. tuberculosis (Mtb), has three main domains, i.e. an N-terminal PE domain, repetitive PGRS domain and the unique C-terminal domain. To investigate the role of these domains, we expressed a GFP-tagged PE_PGRS30 protein and a series of its functional deletion mutants in different mycobacterial species (Mtb, Mycobacterium bovis BCG and Mycobacterium smegmatis) and analysed protein localization by confocal microscopy. We show that PE_PGRS30 localizes at the mycobacterial cell poles in Mtb and M. bovis BCG but not in M. smegmatis and that the PGRS domain of the protein strongly contributes to protein cellular localization in Mtb. Immunofluorescence studies further showed that the unique C-terminal domain of PE_PGRS30 is not available on the surface, except when the PGRS domain is missing. Immunoblot demonstrated that the PGRS domain is required to maintain the protein strongly associated with the non-soluble cellular fraction. These results suggest that the repetitive GGA-GGN repeats of the PGRS domain contain specific sequences that contribute to protein cellular localization and that polar localization might be a key step in the PE_PGRS30-dependent virulence mechanism.
Insights
PE_PGRS30 protein localizes to cell poles in virulent mycobacteria, with the PGRS domain crucial for this localization and virulence. This polar localization may be key to Mycobacterium tuberculosis virulence.
Area of Science:
- Microbiology
- Molecular Biology
- Pathogenesis
Background:
- PE_PGRS proteins are unique to pathogenic mycobacteria.
- PE_PGRS30 is essential for Mycobacterium tuberculosis virulence.
- PE_PGRS30 possesses N-terminal PE, repetitive PGRS, and C-terminal domains.
Purpose of the Study:
- Investigate the role of PE_PGRS30 domains in protein localization.
- Determine the contribution of each domain to PE_PGRS30's function.
- Elucidate the mechanism of PE_PGRS30-mediated virulence.
Main Methods:
- Expression of GFP-tagged PE_PGRS30 and deletion mutants in M. tuberculosis, M. bovis BCG, and M. smegmatis.
- Confocal microscopy for protein localization analysis.
- Immunofluorescence and immunoblot assays to assess surface accessibility and cellular association.
Main Results:
- PE_PGRS30 localizes to cell poles in M. tuberculosis and M. bovis BCG, but not M. smegmatis.
- The PGRS domain significantly contributes to PE_PGRS30's cellular localization in M. tuberculosis.
- The C-terminal domain is surface-exposed only when the PGRS domain is absent; the PGRS domain anchors the protein to the non-soluble fraction.
Conclusions:
- Repetitive sequences within the PGRS domain are critical for PE_PGRS30's polar localization.
- Polar localization of PE_PGRS30 is a potential key mechanism in Mycobacterium tuberculosis virulence.
- Understanding PE_PGRS30 localization provides insights into mycobacterial pathogenesis.
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