Open AccessAdaptations of anaerobic archaea to life under extreme energy limitation
Author(s) -
Mayer Florian,
Müller Volker
Publication year - 2014
Publication title -
fems microbiology reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.91
H-Index - 212
eISSN - 1574-6976
pISSN - 0168-6445
DOI - 10.1111/1574-6976.12043
Subject(s) - atp synthase , chemiosmosis , archaea , biology , electrochemical gradient , atp synthase gamma subunit , methanomicrobiales , biochemistry , electron transport chain , adenosine triphosphate , biophysics , enzyme , atp hydrolysis , membrane , methanosarcina , atpase , gene
Some anaerobic archaea live on substrates that do not allow the synthesis of 1 mol of ATP per mol of substrate. Energy conservation in these cases is only possible by a chemiosmotic mechanism that involves the generation of an electrochemical ion gradient across the cytoplasmatic membrane that then drives ATP synthesis via an A 1 A O ATP synthase. The minimal amount of energy required is thus depending on the magnitude of the electrochemical ion gradient, the phosphorylation potential, and the ion/ ATP ratio of the ATP synthase. Methanogens, T hermococcus , P yrococcus , and I gnicoccus have evolved different ways to energize their membranes, such as methyltransferases, H + , or NAD + reducing electron transport systems fueled by reduced ferredoxin or H 2 ‐dependent sulfur reduction that all operate at the thermodynamic limit of life. The structure and function of the enzymes involved are discussed. Despite the differences in membrane energization, they have in common an A 1 A O ATP synthase that shows an extraordinary divergence in rotor composition and structural adaptations to life under these conditions. In sum, adaptation of anaerobic archaea to energy‐limited substrates involves chemiosmotic energy coupling, often with N a + as coupling ion and a structurally and functionally highly adapted ATP synthase.