The ATPase Motor Turns for Type IV Pilus Assembly

Area of Science:

• Structural Biology
• Biochemistry
• Microbiology

Background:

• Bacterial pili are essential appendages involved in adhesion and motility.
• The assembly of pili is powered by ATP hydrolysis, a process mediated by proteins like PilB.
• Understanding the mechanism of ATP hydrolysis in PilB is crucial for deciphering pilus assembly.

Purpose of the Study:

• To elucidate the crystal structure of the PilB ATPase domain in complex with ATPγS.
• To understand how ATP binding and hydrolysis coordinate conformational changes in PilB.
• To reveal the mechanism by which ATP hydrolysis powers bacterial pilus assembly.

Main Methods:

• X-ray crystallography was used to determine the structure of the PilB ATPase domain.
• Biochemical assays were employed to study ATP binding and hydrolysis.
• Structural analysis was performed to understand conformational changes.

Main Results:

• The crystal structure of the PilB ATPase domain in complex with ATPγS was determined.
• A distinct symmetric rotary mechanism for ATP hydrolysis was identified.
• ATP binding and hydrolysis were shown to coordinate significant conformational changes.

Conclusions:

• The study reveals a novel symmetric rotary mechanism for ATP hydrolysis by PilB.
• This mechanism is essential for powering bacterial pilus assembly.
• The findings provide insights into the molecular basis of pilus biogenesis.