Reading –Alberts Chapter 3 p –Alberts Chapter 6 p –Voet Chapter 30 p

RNA mRNA-messenger RNA tRNA-transfer RNA rRNA-ribosomal RNA

Alberts 3-16

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 ArcheobacteriaYeastBovine 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