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A Structural Perspective on Respiratory Complex IRecruitment of the Antiporter Module – A Key Event in Complex I Evolution

A Structural Perspective on Respiratory Complex I: Recruitment of the Antiporter Module – A Key... [It has long been known that NADH:quinone oxidoreductase or complex I is composed of proteins homologous to other smaller enzymes, electron carriers and transporters. By understanding the recruitment process of each of the smaller functional units, their individual functions and at what stage of complex I building the different functions were needed, we can also better understand the current functional mechanism of this large and intricate molecular machine. This work is focused on the role of the ion translocation proteins, important components of the energy coupling mechanism. We postulate that only one ion transporter protein is actually used for pumping protons in present day complex I, whereas the other two ion transporter proteins form a unit that is used to modulate the output from the proton pumping engine. When recruited to primordial complex I, the modulator unit allowed the proton pumping engine to adapt the stoichiometric output depending on the amount of energy available in different redox couple substrates. This critical step made the emerging complex I a vastly more useful and versatile enzyme, ensuring its evolutionary success. Today, when many members of the complex I family reside in more constant environments and need to use only a limited number of substrates, the most important function of the modulator unit is to function as an antiporter, regulating which type of ion gradient is maintained across the membrane.] http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png

A Structural Perspective on Respiratory Complex IRecruitment of the Antiporter Module – A Key Event in Complex I Evolution

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References (90)

Publisher
Springer Netherlands
Copyright
© Springer Science+Business Media Dordrecht 2012
ISBN
978-94-007-4137-9
Pages
123 –143
DOI
10.1007/978-94-007-4138-6_7
Publisher site
See Chapter on Publisher Site

Abstract

[It has long been known that NADH:quinone oxidoreductase or complex I is composed of proteins homologous to other smaller enzymes, electron carriers and transporters. By understanding the recruitment process of each of the smaller functional units, their individual functions and at what stage of complex I building the different functions were needed, we can also better understand the current functional mechanism of this large and intricate molecular machine. This work is focused on the role of the ion translocation proteins, important components of the energy coupling mechanism. We postulate that only one ion transporter protein is actually used for pumping protons in present day complex I, whereas the other two ion transporter proteins form a unit that is used to modulate the output from the proton pumping engine. When recruited to primordial complex I, the modulator unit allowed the proton pumping engine to adapt the stoichiometric output depending on the amount of energy available in different redox couple substrates. This critical step made the emerging complex I a vastly more useful and versatile enzyme, ensuring its evolutionary success. Today, when many members of the complex I family reside in more constant environments and need to use only a limited number of substrates, the most important function of the modulator unit is to function as an antiporter, regulating which type of ion gradient is maintained across the membrane.]

Published: Apr 10, 2012

Keywords: Mrp antiporter; Ion transport; Proton pumping; Protein evolution; NuoL; NuoM; NuoN

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