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Distinct subunit architecture and assembly pattern of DNA gyrase from mycobacteria
Iqball Faheem1, Richa Gupta1, Valakunja Nagaraja1,2
1Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India.
Molecular Microbiology
|May 16, 2023
Summary
Mycobacterial DNA gyrase (A2B2) assembly differs from other bacteria. GyrA forms tetramers (A4) in mycobacteria, unlike dimers, but still forms the active enzyme with GyrB monomers.
Area of Science:
- Molecular Biology
- Biochemistry
- Microbiology
Background:
- DNA gyrase is a type II topoisomerase essential for DNA replication and transcription.
- It is composed of GyrA and GyrB subunits, forming an A2B2 complex.
- Understanding enzyme assembly is crucial for its activity and potential drug targeting.
Purpose of the Study:
- To investigate the assembly mechanism of DNA gyrase in mycobacteria.
- To compare mycobacterial DNA gyrase assembly with that in other bacterial species.
- To elucidate the role of subunits and DNA in holoenzyme formation.
Main Methods:
- Analytical size-exclusion chromatography was used to study subunit oligomerization.
- Interactions between GyrA and GyrB subunits were analyzed.
- The effect of DNA on enzyme assembly was investigated.
Main Results:
- Mycobacterial GyrA forms stable tetramers (A4) in solution, distinct from the dimeric form in E. coli.
- GyrB exists as a monomer in mycobacteria, similar to E. coli.
- GyrB binding induces dissociation of GyrA tetramers to form the active A2B2 complex.
- DNA binding did not alter GyrA tetramer oligomeric state but stabilized the A2B2 complex in M. smegmatis.
Conclusions:
- Mycobacterial DNA gyrase assembly exhibits a unique pattern involving GyrA tetramer intermediates.
- The distinct assembly pathway highlights differences in mycobacterial enzyme regulation.
- This finding has implications for understanding DNA gyrase function and developing novel antimicrobials.
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