PMC

Photographs showing increased suppression of the ochre mutation in the lacZ gene of the lacZU118 episome in strain MG1655 harboring supE44 compared to the wild type (WT) after 7 days of incubation.

Amber, ochre and opal suppression in HEK293T cells. Immunoblot analysis of proteins isolated from cells co-transfected with plasmids carrying the genes encoding the luciferase reporter, hsup2/C32A38am, hsup2/C32A38oc or the hsup2/C32A38op tRNAs and, when present, E.coli GlnRS. The RLucFLuc fusion protein was detected with an anti-FLuc antibody and E.coli GlnRS was detected with an anti-His4-antibody. An antibody against β-actin was used as a loading control. RLucFLuc, full-length fusion protein; RLucFLuc^*, truncated RLucFLuc fusion protein.

Molecular mechanism of the suppression of the cox15-TAA mutation by SUP7- o. In a cell containing wild-type SUP7, ribosome ceases translation elongation when it reaches the in-frame ochre mutation to produce a C-terminal truncated non-functional polypeptide (left). When an anticodon mutation occurs in the SUP7 gene, the ochre suppressor SUP7- o inserts tyrosine to suppress the ochre codon, and enables translation elongation to proceed in order to produce a full-length polypeptide (right)

SUP4 dependent ochre suppression in absence of nonsense mediated decay. Plate assays of ade2-1 and can1-100 suppression by SUP4. Strains of the indicated genetic backgrounds were spotted on +Ade, −Ade or −Arg/+Can media and photographed after 40 h of incubation at 30 °C (+Ade and −Arg/+Can) or at the indicated time points (−Ade).