Subunit composition, structure, and distribution of bacterial V-type ATPases

Area of Science:

• Biochemistry
• Structural Biology
• Molecular Biology

Background:

• Vacuolar-type proton ATPases (V-ATPases) are essential molecular machines involved in various cellular processes.
• Their overall structure is similar to F-type ATPases, but the stalk region exhibits greater complexity.
• Understanding the V-ATPase structure is crucial for deciphering its function in different organisms.

Purpose of the Study:

• To investigate the evolutionary relationships and structural diversity of V-ATPases across different domains of life.
• To clarify the nomenclature inconsistencies related to V-ATPase types and subunits.
• To propose a structural model for prokaryotic and eukaryotic V-ATPases based on sequence and structural data.

Main Methods:

• Extensive database searches were conducted to identify V-ATPase sequences.
• Bioinformatic sequence analysis was performed on the five water-soluble stalk region subunits (C-G).
• Existing biochemical, cross-linking, and electron microscopy data were reviewed to assign subunit positions.

Main Results:

• V-ATPases have been identified in 16 bacterial species to date.
• Bacterial V-ATPases demonstrate closer evolutionary ties to archaeal A-ATPases than to eukaryotic V-ATPases.
• Distinct groups of bacterial V-ATPases were identified, suggesting functional or structural variations.
• A proposed structural model differentiates prokaryotic V-ATPases (central stalk with two peripheral stalks) from eukaryotic V-ATPases (an additional peripheral stalk).

Conclusions:

• Bacterial V-ATPases represent a distinct evolutionary lineage, closer to archaeal counterparts.
• The structural complexity of the V-ATPase stalk region varies between prokaryotes and eukaryotes.
• The proposed structural model provides a framework for understanding V-ATPase architecture and evolution.