ABSTRACT
Mycobacterium tuberculosis uses the ESAT-6 system-1/type VII (ESX-1) system for secretion of virulence proteins into the host cell, however the mechanism of virulence proteins secretion, molecular components and regulation of ESX-1 system are only partly understood. In the current study, we have analyzed the biological function and recognition mechanism between ESX-1 virulence EspC and EccA1 ATPase proteins. The EspC enters into A549 human lung carcinoma cells and exhibited cytotoxicity, as observed in MTT Assay. To understand the recognition mechanism between EspC and EccA1 ATPase, the EspC and EccA1 mutants were generated based on EspC~EccA1 interactions, as observed in molecular modeling. Binding analysis shows that EspC export arm interacts specifically to the β-hairpin insertion motif of the TPR domain of EccA1 ATPase. Mutations in these epitopes lead to significant decrease/or abolish the binding between EspC and EccA1 ATPase. Our study provides insight into biological function and recognition mechanism between EspC and EccA1 ATPase, which can be used as target to prevent EspC secretion/ or in general virulence factor secretion by mycobacterial ESX-1 system.
Competing Interest Statement
The authors have declared no competing interest.
ABBREVIATIONS
- ATP
- Adenosine Triphosphate
- EspC
- ESX-1 secreted protein C
- EspB
- ESX-1 secreted protein B
- EccA1
- ESX-1 conserved AAA+ATPase
- CFP10
- Culture Filtrate protein-10
- ESAT6
- Early Secretory Antigen Target-6
- CD
- Circular Dichroism
- TPR
- Tertratricopeptide repeat
- OD
- Optical Density
- Ni-NTA
- Nickel-Nitriloacetic Acid
- SDS PAGE
- Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis
- SPR
- Surface Plasmon Resonance
- PBS buffer
- Phosphate buffered saline
- PBST buffer
- Phosphate buffered saline with Tween-20.