Conformational Plasticity Of Protein Nanoturbine

Innovation study of the structure of protein nanoturbine revealing in the study; showing that Cells rely on protein complexes known as ATP synthases or ATPases for their energy needs. Adenosine triphosphate (ATP) molecules power most of the processes sustaining life. By this  determining the first atomic structure of the representative of the V/A-ATPase family; filling in the gap in the evolutionary tree of these essential molecular machines.

But the ATP synthases/ATPases are large membrane protein complexes; which share overall gross building plans and rotary catalysis mechanisms. This protein family includes F-type enzyme found in mitochondria, chloroplasts and bacteria; vacuolar type finding in intracellular compartments in eukaryotes and archaeal type found in prokaryotes archaea and some bacteria.

But this showing different flavors of ATPase F- and A-type enzymes usually function to produce ATP, driven by proton flow across the membrane. V-type enzymes usually work in reverse, using ATP to pump protons. V- and A-ATPases are similar structurally but they differ from the F-type by having two or three peripheral stalks and additional connecting protein subunits between V1 and Vo.

Structure of protein nanoturbine

according ton the study V-type enzymes probably evolving from the A-type and because of these similarities A-type is also termed V/A-ATPase. Some bacteria, including Thermus thermophilus, acquired an A-type enzyme. Long Zhou, postdoc in the Sazanov research group of IST Austria, has purified and studied this enzyme (ThV1Vo) by cryo-EM.

The scientists determined not one, but in total five structures of the entire ThV1Vo enzyme, using cryo-electron microscopy methods developed recently in the so-called “resolution revolution” of this technique. The structures represent several conformational states of the enzyme differing by the position of the rotor inside the stator.

Global conformational plasticity

Global conformational plasticity of ThV1Vo is revealed as substantial V1 wobbling in space in transition from one state to another. It is a result of mechanical competition between rotation of the bent central rotor and stiffness of the stator. V1-Vo coupling is achieved via close structural and electrostatic match between the shaft and V-type specific subunit linking it to the c-ring.

The visualization of the proton path revealing significant differences; in the distribution of charging protein residue from; that in F-ATPases, with a stricter “check-point” preventing “slipping” of the enzyme. Instead of a single peripheral stalk of F-type enzymes; A-types such as ThV1Vo have two peripheral stalks, while eukaryotic V-types have three. But what is the advantage of the additional complexity in the already very large protein assembly, along with additional subunits linking V1 and Vo