Differential roles of putative arginine fingers of AAA⁺ ATPases Rvb1 and Rvb2

Area of Science:

• Molecular Biology
• Biochemistry
• Structural Biology

Background:

• The evolutionarily conserved Rvb1 and Rvb2 proteins form a heteromeric complex (Rvb1/2) essential for various cellular processes, including chromatin remodeling and ribosome biogenesis.
• Rvb1 and Rvb2 share high sequence and structural similarity, possessing conserved ATPase domains with key motifs like Walker A, Walker B, Sensor I, Sensor II, and an arginine finger.

Approach:

• Investigated distinct active sites of Rvb1 and Rvb2 within the Rvb1/2 complex using biochemical and genetic methods.
• Employed molecular dynamics simulations to analyze the impact of active site modifications on protein dynamics and long-range communication.
• Validated findings through assessment of snoRNP biogenesis and a targeted genetic screen.

Key Points:

• Despite structural similarity, Rvb1 and Rvb2 exhibit distinct active sites that influence their catalytic activity and regulation within the Rvb1/2 complex.
• Modifications to the arginine finger residues in Rvb1 and Rvb2 differentially affect complex activity, cell growth, and interactions with binding partners.
• Molecular dynamics simulations revealed long-range effects from active site changes to the insertion domain, suggesting a mechanism for functional modulation.

Conclusions:

• The study identifies a novel relay mechanism of long-range molecular communication from the ATPase active site to cofactor binding sites in the Rvb1/2 complex.
• Rvb1 and Rvb2, despite their cooperation, possess unique properties critical for the complex's regulation and function.
• Findings shed light on the intricate regulation of essential macromolecular complexes through differential protein properties within a heteromeric structure.