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| Daniela Stock - | |
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ATP synthase, or F-type ATPase, is central to biological energy conversion.
Photosynthetic and respiratory systems of all living organisms convert
energy derived from light or from nutrients into transmembrane
electrochemical proton gradients. ATP synthase uses energy stored
in these gradients to synthesise the universal biological energy carrier
ATP from ADP and inorganic phosphate. The transmembrane Fo sector of the
enzyme contains a rotary motor that is fuelled by the proton gradient
similar to a turbine. The rotary torque induced by the passage of protons
through Fo is transmitted via a central stalk to the catalytic subunits in
the soluble F1 domain, where the rotation induces conformational changes
that enable the synthesis and subsequent release of ATP.
Eukaryotic vacuolar (V-type) ATPases operate in reverse: They utilise
energy derived from ATP hydrolysis to build up transmembrane ion gradients.
V-type ATPases play an important role in pH homeostasis and enable transport
processes across membranes. While most eubacterial ATPases are of the
F-type, some eubacteria and all known archaea have ATPases of the A-type,
which are close homologues of V-type ATPases, but are used for ATP
synthesis. Although V- and A-type ATPases are similar in size and shape to
F-type ATPases, only the catalytic subunits and the core of the
transmembrane motor share significant sequence homology.
In my talk I will discuss the X-ray structure of the F1c10 complex from
yeast mitochondria, which represents the largest structurally known portion
of any type of ATPase to date. I will compare this structure to a lower
resolution 3D reconstruction of an intact eubacterial A-type ATPase
obtained by electron microscopy.
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