2009 Nobel Prize in Chemistry was awarded to
Venkatraman Ramakrishnan,
Thomas A. Steitz and
Ada E. Yonath for having showed what the
ribosome looks like and how it functions at the atomic level. All
three have used X-ray crystallography and high-resolution cryo-electron
microscopy (freeze-fracture EM) to map the
position for each and every one of the hundreds of thousands of
atoms that make up the ribosome. "All three have generated
3D models
that show how different antibiotics bind to the ribosome. These
models are now used by scientists in order to develop new
antibiotics, directly assisting the saving of lives and decreasing
humanity's suffering".
 |
Ada
Yonath’s work |
Thomas Steitz and collaborators in 1999 were the first to solve the profoundly challenging phase problem of the 50S structure from
H. marismortui. Since the phase problem had not been solved for the 30S subunit at this time, this meant a decisive break through in ribosomal crystallography. For this, they initially used a cryo-electron microscopy (cryo-EM) reconstruction of the ribosomal 50S subunit .
The same year a 5.5 Å resolution structure of the 30S subunit (T. thermophilus) appeared from V. Ramakrishnan and collaborators (Clemons et al., 1999) soon followed by a 4.5 Å resolution structure of the T. thermophilus 30S subunit from Yonath and collaborators (Tocilj et al., 1999). In the same year, Harry Noller and collaborators at UCSC reported the structure of the 70S ribosome from T. thermophilus at 7.8Å resolution, containing tRNAs in the ribosomal A, P and E sites and a mRNA in the track around the neck of the 30S subunit (Cate et al., 1999). Neither one of these structures displayed high enough resolution to construct complete atomic models, but they provided the necessary stepping stones on the path to the high resolution structures to rapidly follow.
When the structures of the two ribosomal subunits had been obtained at high resolution it suggested that the peptidyl-transferase center, where peptide bond formation occurs, lacked ribosomal proteins components, which supported the earlier suggestions of Noller (1992) that the ribosome is a RIBOZYME.