Janelia Research Campus
Dr. Grigorieff is a group leader at the Janelia Research Campus. He is also a visiting professor at Brandeis University. He was an HHMI investigator at Brandeis from 2000 to 2013.
Electron Microscopy of Large Molecular Assemblies and Membrane Proteins
Nikolaus Grigorieff has always enjoyed figuring out how electronic gadgets work, building them, and speaking their language using mathematics, circuitry diagrams, and computer algorithms.
As a boy, he used a toaster and two pieces of pencil graphite to construct an arc lamp, which used electricity to create a bright light. To tease his mother, who would shut off the electricity in the house when he played his music too loud, Grigorieff built a generator to independently operate his stereo. He even programmed an early computer to play the game "Battleship" with himand lost.
Today, Grigorieff's gadget of choice is a 300,000-volt electron microscope (EM), which he uses to see molecules that operate as minute biological "machines" inside of cells. Grigorieff writes his own specialized computer software to transform data from the microscope into vivid, three-dimensional images of a cell's components.
"Most processes in the cell come down to chemistry," Grigorieff explains. "Chemical reactions are performed by atoms or groups of atoms, so you need to know where and how these atoms are arranged."
Grigorieff came to biology after studying physics. His Ph.D. thesis focused on semiconductor devices and their analysis with the EM. But the work was more concerned with engineering, he says, than an intellectual quest to explore new territory. "I always felt biology was discovery of entirely unknown things and that fascinated me more," he says.
As a postdoctoral fellow at the Medical Research Council in England, he used the EM to study large biological complexes. At the time, scientists couldn't see the level of detail that they would have liked in these structures. So Grigorieff developed EM techniques and algorithms to make higher-resolution images of protein complexes inside cells to reveal greater detail.
In particular, Grigorieff studied the structure of the first enzyme complex in the electron transport chain in the mitochondrion. The organelle uses molecules within it to extract energy from sugar.
Grigorieff was able to obtain a 20-Angström-resolution structure of the complex, improving upon earlier structures of this complex. Resolution distinguishes two points in a structurethe smaller the resolution value, the greater the ability to see more detail.
During the past decade, Grigorieff has improved his method and achieved resolutions of 3.8 Angströms in some structures. "In order to get the high-resolution detail we can now achieve, we take a lot of images," he says.
Once he has taken many pictures of the molecule, Grigorieff uses the computer algorithms he has written to reassemble the structure. "Our process is analogous to computerized tomography, when radiologists take x-rays of an organ from different points of view and reconstruct a three-dimensional image," Grigorieff explains. "We don't know beforehand what side we are taking. But we have devised ways to infer where each image of the molecule belongs in terms of top, bottom, side, or whatever. Then, we put it together three dimensionally."
Grigorieff hopes to improve the resolution of complex structures to, perhaps, 2 Angströms. But the task is challenging. "Most biological complexes exist in many forms," Grigorieff says. Recently, he obtained high-resolution images of Alzheimer's disease fibrils, which can be highly irregular. It remains to be seen if he can be successful with other complicated molecules.
Grigorieff attributes some of his success and aptitude in a field that bridges physics, biology, mathematics, and computer science to his experiences growing up in West Berlin before the Wall fell. "When you live at a border you have a direct experience of the truth, no matter what the propaganda says. We couldn't just say all Communists were bad. We were dependent on them and knew some of them. It wasn't black and white," he says.
"When there are different systems, you build up all sorts of theories about the other systems, but truth happens at the border. The borders where I operate in science let me see many different perspectives and the consequences of the things that impact that border."
In 2013 Grigorieff became a lab head at HHMI's Janelia Research Campus.