Noller, Harry

Obviously, Harry [Noller] s finding doesn t speak to how life started, and it doesn t explain what came before RNA. But as part of the continually growing body of circumstantial evidence that there was a life form before us on this planet, from which we emerged—boy, it s very strong ... 

Recently Harry Noller has extended the range of ribozymes to include peptide bond catalysis. Noller and his colleagues found that the removal of all protein from the ribosomes of certain thermophilic bacteria left the ribosomes with the ability to catalyze peptide bond formation. 

We thank Dr. Elizabeth Zimmer for proposing an evolutionary comparison of RNA secondary structures in plants and Dr. Harry Noller for encouragement and communications during the course of this study. We also thank Dr. Michael Arnold for constructive criticism and comments on the manuscript. This work was supported by a giant from the U.S. Department of Energy to R.B.M. and an National Institutes of Health postdoctoral fellowship to J.F.S. 

Figure 29.17. Ribosomal RNA Folding Pattern. (A) The secondary structure of 16S ribosomal RNA deduced from sequence comparison and the results of chemical studies. (B) The tertiary structure of 16S RNA determined hy x-ray crystallography. [Part A courtesy of Dr. Bryn Weiser and Dr. Harry Noller.]...

A) Courtesy of Dr. Bryn Weiser and Dr. Harry Noller (B) drawn fromi IFJG.pdb.]... 

In the second step of elongation, the a-amino group of the amino acid in the A site (AA2) acts as a nucleophile and attacks the carbonyl group of AA1 (in this case fMet). This reaction leads to the formation of a dipeptidyl-tRNA in the A site and a deacylated-tRNAfMet in the P site (Fig. 26.12). As shown by Harry Noller in 1992, this peptidyl transferase reaction is catalyzed by ribozyme activity present in the 23 S rRNA of the 50S ribosome subunit (and the 28S rRNA in the 60S ribosome subunit in eukaryotes), rather than by ribosomal proteins, as originally thought. 

US molecular biologist Harry Noller and colleagues produce first detailed X-ray crystallographic image of a complete ribosome. 

Figure 25.13 Structure of the Thermus thermophilus ribosome showing the SOS and SOS subunits and three bound transfer RNAs. The yellow tRNA is at the A site, which would bear the new amino acid to be added to the peptide. The light orange tRNA is at the P site, which would be the tRNA that bears the growing peptide. The red tRNA is at the E site, which is the "empty" tRNA after it has transferred the peptide chain to the new amino acid. (Courtesy of Harry Noller, University of California, Santa Cruz.)...

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