• Reading– Alberts Chapter 3 p. 98-111– Alberts Chapter 6 p. 223-231– Voet Chapter 30 p. 981-991

RNA

• mRNA-messenger RNA

• tRNA-transfer RNA

• rRNA-ribosomal RNA

Alberts 3-16

Alberts 3-18

Alberts 3-18

Alberts 6-11

Alberts 6-14

rRNA

• Major components of large RNA-protein complex--ribosome

• Ribosome is the catalytic machinery involved in translation

Alberts 8-62

Alberts 6-20

How do we study complex structures?

• Purification of subunits and reconstitution in vitro

• Electron microscopy

• Antibody crosslinking

• Crystallography

Voet and Voet 30-25

Voet and Voet 30-27

Voet 30-36

Archeobacteria Yeast Bovine mitochondria

Alberts 6-19

Challenges

• How do all the parts fit into this structure?– 3-4 RNA molecules and over 50 proteins

• Where is the function?– In the 60’s people assumed that the functions of

the ribosome was due to proteins

• Reconstitution experiments--can make Functional ribosomal subunits in a test tube starting with purified parts– Masayasu Nomura

– Partial reconstructions used to map proper order of assembly

– Order of addition important for functional ribosome

– Indicates the ribosome is a self-assembling structure and that isolated retain native structure

Voet and Voet 30-32

Catalytic activity

• Knoller and colleagues circa 1992– Demonstrate that rRNA of the large subunit is

capable of peptidyl transferase activity independent of any proteins.

• Watanabe and colleagues circa 1998– Synthetic fragments of 23S rRNA catalyze

formation of peptide bonds.

Alberts 6-21

Alberts 6-22

Alberts 6-23

Alberts 6-24

Alberts 6-25

Alberts 6-22

Alberts 6-30

Alberts 6-28

Alberts 6-29