Crystal structure of the apurinic/apyrimidinic endonuclease IV from Mycobacterium tuberculosis

Area of Science:

• Biochemistry
• Structural Biology
• Microbiology

Background:

• Endonuclease IV is a key enzyme in DNA base excision repair.
• In Mycobacterium tuberculosis, it is the primary AP endonuclease.
• Its absence in mammals makes it a promising target for tuberculosis drug development.

Purpose of the Study:

• To determine the high-resolution crystal structure of recombinant Mycobacterium tuberculosis endonuclease IV (MtbEndo IV).
• To elucidate the structural basis for its DNA repair function.
• To identify potential targets for anti-tuberculosis drug design.

Main Methods:

• Recombinant expression and purification of MtbEndo IV.
• X-ray crystallography to determine the enzyme's three-dimensional structure.
• Structural comparison with homologous enzymes, such as E. coli End IV.

Main Results:

• The crystal structure of MtbEndo IV was determined at 1.18 Å resolution.
• The enzyme exhibits a canonical α8β8-fold TIM barrel structure.
• Three zinc ions were identified at the active site, crucial for catalytic activity.
• A surface groove suitable for DNA binding was observed.
• Structural comparison suggested a role for Gln32 in substrate binding regulation.

Conclusions:

• The determined structure provides atomic-level insights into MtbEndo IV's function.
• Understanding MtbEndo IV's structure is vital for developing novel anti-tuberculosis therapies.
• The identified structural features offer a basis for structure-based drug design against MtbEndo IV.