Structural Characterization of Mycobacterium tuberculosis Encapsulin in Complex with Dye-Decolorizing Peroxide

Area of Science:

• Structural biology
• Microbiology
• Biochemistry

Background:

• Mycobacterium tuberculosis (Mtb) causes tuberculosis, the deadliest infectious disease.
• Mtb evades host defenses and survives in macrophages via oxidative stress response.
• Dye-decolorizing peroxidase (DyP) within encapsulin (Enc) aids Mtb survival in macrophages.

Purpose of the Study:

• To determine the crystal structure of the Mtb-Enc•DyP complex.
• To compare the crystal structure with cryo-EM structures of Mtb-Enc.
• To investigate Mtb-Enc pore structure and DyP-TP binding.

Main Methods:

• X-ray crystallography of the Mtb-Enc•DyP complex.
• Comparison with existing cryo-EM data of Mtb-Enc.
• Analysis of electron density for DyP-TP and small-molecule binding sites.

Main Results:

• The crystal structure of Mtb-Enc•DyP was determined.
• Significant differences were observed in the five-fold pore structure compared to cryo-EM data.
• Electron density for the DyP targeting peptide (TP) was identified within the Enc shell.
• Potential small-molecule binding sites within Mtb-Enc were revealed.

Conclusions:

• The Mtb-Enc•DyP structure provides insights into Mtb's intracellular survival mechanisms.
• Structural variations in Mtb-Enc pores may influence substrate entry or function.
• Understanding these interactions can guide the development of novel anti-tuberculosis strategies.