Dictyostelia (social amoebas)

TLS Online TPP Program

#Id: 3644

#Unit 3. Fundamental Processes

Many Classes I aaRSs must recognize the anticodon to aminoacylate their cognate tRNAs.

TLS Online TPP Program

#Id: 3645

#Unit 3. Fundamental Processes

Several Class II enzymes do not interact with their bound tRNA’s anticodon.

TLS Online TPP Program

#Id: 3646

#Unit 3. Fundamental Processes

All Class I enzymes aminoacylate their bound tRNA’s 3′-terminal 2′-OH group, whereas Class II enzymes charge the 3′-OH group.

TLS Online TPP Program

#Id: 3647

#Unit 3. Fundamental Processes

The amino acids for which the Class I synthetases are specific tend to be larger and more hydrophobic than those for Class II synthetases.

TLS Online TPP Program

#Id: 3648

#Unit 3. Fundamental Processes

In ValRS, the side chain of Asp 279 protrudes into the editing active site, where it hydrogen-bonds with the hydroxyl group of threonine. The isosteric (having the same shape) valine lacks this hydroxyl group and is thereby excluded from the editing pocket.

TLS Online TPP Program

#Id: 3649

#Unit 3. Fundamental Processes

Valine cannot coordinate the Zn2+ in this way and hence does not undergo adenylation by ThrRS. A separate editing site deal with misacylated Ser–tRNAThr.