Molecular architecture of the augmin complex

Area of Science:

• Cell Biology
• Structural Biology
• Biochemistry

Background:

• Mitotic spindle assembly is vital for accurate chromosome segregation.
• The augmin complex (HAUS) is essential for robust spindle formation in metazoa.
• Augmin promotes microtubule branching nucleation and recruits the γ-tubulin ring complex (γ-TuRC).

Purpose of the Study:

• To elucidate the molecular architecture of the augmin complex.
• To understand the structural basis of augmin's function in microtubule organization.

Main Methods:

• Single particle cryo-electron microscopy (cryo-EM)
• Computational modeling
• Crosslinking mass spectrometry (CLMS)

Main Results:

• Determined the molecular architecture of the eight-subunit augmin complex.
• Revealed a flexible V-shaped head and a filamentous tail.
• Identified extended and contracted conformational states of the augmin head.

Conclusions:

• Cryo-EM, computational methods, and CLMS successfully elucidated the structure of the challenging augmin complex.
• The revealed structure provides insights into augmin's mechanism of microtubule branching nucleation.
• Understanding augmin's structure is key to comprehending mitotic spindle assembly and stability.