THE HOLY GRAIL: Structure of a Nanomachine If seeing is believing, how do scientists see cellular nanomachines, smaller than the wavelength of visible light? One way is to use a beam of electrons 100,000 times smaller than ordinary light to peer at individual atoms. But the energy of the powerful 200,000 volt electron beam can destroy the protein being imaged: imagine the radiation damage if you stood 20 m away from a thermonuclear device.
• Take a Chill Pill: To cut down on damage to delicate chemical bonds, scientists use a variation known as Cryo EM. First, they place the purified sample on to a microfabricated carbon grid. Then they plunge it into a bath of liquid ethane that instantly vitrifies water, not allowing it to form crystals. This preserves the molecules in its native state. Using only a small puff of electrons, they image the sample in liquid nitrogen in a vacuum. The resulting underexposed and overdeveloped image is disappointingly grainy. So they average many images of the same view to sharpen the resolution and cut down on noise. The 3D image is made from a series of tilted 2D images.
• Tripping on Acid: The image seen in gray scale is at an unprecedented 9.7 angstroms resolution (or 0.97 nm) of a nanomachine from an ancient bacteria, Thermus thermophilus. Although it functions as a rotary ATP synthase, it resembles the V-ATPase found in our cells- another rotary machine that works in reverse: breaking down ATP to acidify compartments. The V-ATPase and the ATP synthase share a common evolutionary origin seen in ancient archaebacteria like Thermus.
• Intel Inside: Inside the gray outline seen by cryo-EM are the individual proteins that make up this nanomachine, observed by X-ray imaging. Compared to the ATP synthase (goo.gl/gjiZN), the V-ATPase is even more complex and sophisticated.
➤ Many thanks to expert gif-fer and science enthusiast Kevin Staff who converted the original movie for your viewing pleasure! Check out Kevin’s original style and wit on his profile.
♫ Konstantin Lamanov saw the HOLY GRAIL and suggested the mystical melody of “The Holy Grail” Composed by Laurence Galian
Thank you for the musical pairing, Konstantin Lamanov as always 🙂
REF: Subnanometre-resolution structure of the intact Thermus thermophilus H+-driven ATP synthase.Lau WC, Rubinstein JL. Nature. 2011 Dec 18;481(7380):214-8. doi: 10.1038/nature10699
John Rubinstein: http://biochemistry.utoronto.ca/rubinstein/bch.html