Deciphering cellular and molecular determinants of human DPCD protein in complex with RUVBL1/RUVBL2 AAA-ATPases

Area of Science:

• Molecular and Cellular Biology
• Structural Biology
• Biochemistry

Background:

• DPCD protein's role in cilia formation and primary ciliary dyskinesia (PCD) is suggested but poorly understood.
• RUVBL1 (R1) and RUVBL2 (R2) are conserved AAA+ ATPases crucial for macromolecular complex assembly and cellular processes.
• Previous high-throughput studies hinted at DPCD as a potential R1 and R2 binding partner.

Purpose of the Study:

• To investigate the interaction between DPCD and the R1R2 complex.
• To characterize the biochemical and structural properties of DPCD and its complex with R1R2.
• To elucidate the molecular mechanisms underlying DPCD's interaction with R1R2.

Main Methods:

• In vivo and in vitro interaction studies to confirm DPCD-R1R2 binding.
• Physico-chemical characterization of DPCD in solution and 3D model construction.
• Orthogonal biophysical techniques: small-angle X-ray scattering (SAXS), structural mass spectrometry, and electron microscopy.

Main Results:

• DPCD was identified as a novel in vivo binding partner of R1R2.
• Direct interaction between DPCD and R1R2 was confirmed both in vitro and in cellular contexts.
• DPCD binding disrupts the dodecameric R1R2 complex, primarily through interaction with the R1R2 DII domains.

Conclusions:

• DPCD directly interacts with R1 and R2 proteins, establishing it as a new R1R2 partner.
• The interaction between DPCD and R1R2 has significant structural implications, altering the R1R2 complex's quaternary structure.
• This study provides foundational insights into the molecular mechanisms of DPCD function, potentially relevant to cilia biology and PCD.