DNA deformability in sequence-dependent capture of E. coli gyrase

Area of Science:

• Structural Biology
• Molecular Biology
• Biophysics

Background:

• Bacterial DNA gyrase is a crucial enzyme for DNA replication, transcription, and repair.
• Understanding DNA-gyrase interactions is key to developing novel antibiotics.
• Previous studies utilized cryo-electron microscopy (cryoEM) to visualize DNA-gyrase complexes.

Purpose of the Study:

• To investigate the role of DNA sequence and deformability in E. coli gyrase binding.
• To develop a novel methodology for DNA sequence determination from cryoEM density maps.
• To elucidate how DNA structure influences gyrase's site selection and function.

Main Methods:

• Developed a shape-based recognition methodology to identify DNA sequences from cryoEM density maps.
• Analyzed two cryoEM structures of negatively supercoiled DNA bound to E. coli gyrase.
• Assessed DNA sequence flexibility and base-pair step deformability within the complexes.

Main Results:

• Successfully identified DNA sequences from cryoEM maps, matching previously determined sequences.
• Observed distinct DNA sequence and flexibility patterns in two gyrase-DNA complex structures.
• Demonstrated that flexible DNA facilitates bending for gyrase binding, while inflexible sequences prevent it.

Conclusions:

• DNA sequence and its inherent deformability significantly impact E. coli gyrase binding and function.
• The developed methodology provides a valuable tool for analyzing DNA sequences in cryoEM structures.
• This research enhances our understanding of DNA-protein interactions and gyrase mechanism.