Evolutionary primacy of sodium bioenergetics

Armen Y Mulkidjanian,Yuri I Wolf,Eugene V Koonin,Michael Y Galperin,Kira S Makarova

doi:10.1186/1745-6150-3-13

Abstract

BackgroundThe F- and V-type ATPases are rotary molecular machines that couple translocation of protons or sodium ions across the membrane to the synthesis or hydrolysis of ATP. Both the F-type (found in most bacteria and eukaryotic mitochondria and chloroplasts) and V-type (found in archaea, some bacteria, and eukaryotic vacuoles) ATPases can translocate either protons or sodium ions. The prevalent proton-dependent ATPases are generally viewed as the primary form of the enzyme whereas the sodium-translocating ATPases of some prokaryotes are usually construed as an exotic adaptation to survival in extreme environments.ResultsWe combine structural and phylogenetic analyses to clarify the evolutionary relation between the proton- and sodium-translocating ATPases. A comparison of the structures of the membrane-embedded oligomeric proteolipid rings of sodium-dependent F- and V-ATPases reveals nearly identical sets of amino acids involved in sodium binding. We show that the sodium-dependent ATPases are scattered among proton-dependent ATPases in both the F- and the V-branches of the phylogenetic tree.ConclusionBarring convergent emergence of the same set of ligands in several lineages, these findings indicate that the use of sodium gradient for ATP synthesis is the ancestral modality of membrane bioenergetics. Thus, a primitive, sodium-impermeable but proton-permeable cell membrane that harboured a set of sodium-transporting enzymes appears to have been the evolutionary predecessor of the more structurally demanding proton-tight membranes. The use of proton as the coupling ion appears to be a later innovation that emerged on several independent occasions.ReviewersThis article was reviewed by J. Peter Gogarten, Martijn A. Huynen, and Igor B. Zhulin. For the full reviews, please go to the Reviewers' comments section.

Highlights

The F- and V-type ATPases are rotary molecular machines that couple translocation of protons or sodium ions across the membrane to the synthesis or hydrolysis of ATP
The F/V type ATPases, are unique functionally, because they can efficiently operate in the ATP synthase regimen, and mechanistically, in that their reaction cycle is accompanied by rotation of one enzyme part relative to the other [3,15,16,17]
While most authors prefer to speak of eukaryotic and bacterial V-type ATPases [7,9,38], some consider prokaryotic V-ATPases to be a separate group of A-type ATPases, at the same level with eukaryotic V-type ATPases and F-type ATPases [5,40,41]

Summary

Introduction

The F- and V-type ATPases are rotary molecular machines that couple translocation of protons or sodium ions across the membrane to the synthesis or hydrolysis of ATP. The vast majority of the cellular ATP is produced by the membrane ATP synthases, reversible, rotary molecular machines that couple ion transfer across the membrane with the synthesis or hydrolysis of ATP. These machines belong to two distinct types, namely, F-type that is present in bacteria and eukaryotic organelles [1,2,3,4] and V-type, represented in archaea and in some bacteria [5,6,7,8,9]. The F/V type ATPases, are unique functionally, because they can efficiently operate in the ATP synthase regimen, and mechanistically, in that their reaction cycle is accompanied by rotation of one enzyme part (rotor) relative to the other (stator) [3,15,16,17]

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Results

Conclusion