Comparison of Proline-glutamate-proline-glutamate-polymorphic GC-rich Sequences Family Protein Wag22 (Rv1759c), PE_PGRS31 (Rv1768), PE_PGRS32 (Rv1803), and PE_PGRS33 gene (Rv1818c) in Exponential State and Under In vitro Model of Latency in Same Clin
Parissa Farnia, Poopak Farnia, Jalaledin Ghanavi, Saman Ayoubi, Saeid Besharati, Ali Akbar Velayati- Biotechnology
Abstract
Background:
Proline-glutamate (PE)/proline-PE (PPE) proteins play an important role in the development of mycobacterial pathogenicity by modulating the host immune system. In the present investigation, the structural changes in PE-polymorphic GC-rich sequences (PGRS) family protein Wag22 (Rv1759c), PE_PGRS31 (Rv1768), PE_PGRS32 (Rv1803), and PE_PGRS33 gene (Rv1818c) were compared and analyzed in exponential state and under
Methods:
MTB strains were isolated from clinically and laboratory-confirmed cases of tuberculosis (TB). The TB isolates were subjected to the Xpert MTB/rifampin test and then, further susceptibility testing using proportional methods was performed on them. The isolates were characterized using both 16S–23S RNA and
Results:
No deletion, insertion, or substation occurred in susceptible, mono-drug and multidrug resistant-TB isolates were observed at PE-PGRS family protein Wag22 (Rv1759c) and PE_PGRS31 (Rv1768) at exponential phase. Although, a large deletion (at Rv1759c; Rv1768) was observed in extensively drug-resistant (XDR) and totally drug-resistant (TDR) TB isolates at the exponential phase. All studied TDR-TB isolates had a common deletion position from amino acid 1 (methionine) to amino acid 83 (glycine) and from amino acid 725 (proline) to amino acid 914 (threonine) at PE-PGRS family protein Wag22 (Rv1759c). At PE_PGRS32 (Rv1803), deletion occurred from amino acid 1 (methionine) to amino acid 212 (glycine) in latent TDR-TB bacilli. No changes in Rv1803 were observed in other studied isolates. In contrast, 66.6% of studied isolates had either insertion, deletion, substitution, or combination of changes at PE_PGRS33 (Rv1818c). However, the majority of changes at Rv1818c occurred in drug-resistant isolates. We also documented the region of deletion and insertion at PE_PGRS33 (Rv1818c) is different in active and latent TDR-TB isolates.
Conclusions:
Changes in these PE-PGRS family protein was associated with drug susceptibility patterns of individual isolates. Our result showed a total frameshift mutation of protein that had a different length in comparison to the original protein. These changes might disturb the interactions between XDR and TDR-TB isolates and immune responses, which needs further investigation.