Electron transport and energy conservation in the archaebacterium Sulfolobus acidocaldarius

Abstract

The bioenergetic properties of the thermoacidophilic archaebacterium Sulfolobus acidocaldarius are reviewed and discussed under the aspect whether this archaebacterium conserved energy by oxidative phosphorylation and how the involved catalysts are related to those from eubacteria and eukaryotes. The thermodynamic parameters contributing to the proton-motive force and the efficiency of proton pumping are presented. The major components of the electron transport system are identified and a novel type of heme-aa₃ containing terminal oxidase is described, oxidizing reduced caldariella quinone. The properties of an F₁-analogous ATPase and of a DCCD-binding proteolipid from the plasmamembrane of Sulfolobus are discussed as likely components of an F₀F₁-analogous ATP-synthase. The structural and functional properties of this and other archaebacterial ATPases are compared to each other and with respect to evolutionary relations.