Suppressors Flashcards
What is a suppressor?
Two mutations that cancel each other out and revert the mutant back to WT
What are the two classes of suppression?
True reversion
Pseudo reversion
What are the two classes of pseudo reversion?
Intragenic
Extragenic
What does a true reversion do?
Fixes genotype
What does a pseudo reversion do?
Fixes phenotype
A second indel fixing a Frameshift is what type of suppression?
Intragenic
A second mutation fixing a mutation in FtsZ’s ATP binding pocket by further altering the pocket is what type of suppression?
Intragenic, different codon
What is conformational suppression?
It restores an interaction or activity based on structure
Is conformational suppression intragenic or extragenic?
Both
Is conformational suppression gene or allele specific?
Both
What the the types of conformational suppression?
RNA-RNA
Protein-DNA
Protein-protein
What’s an example of RNA-RNA conformational suppression?
A mutated ribosome regains binding via another mutation
What’s an example of protein-DNA conformational suppression?
A protein is mutated but then can binds to a mutated binding site
What’s an example of protein-protein conformational suppression?
The lock and key example with the semicircles with various shapes carved into them
What are the types of extragenic suppression?
Conformational
Informational
Bypass
What’s an informational suppressor?
Changes how the mutation is read or decoded
Is informational suppression gene or allele specific?
Allele specific only
What are the types of informational suppressors?
Nonsense
Frameshift suppressors
What is a nonsense suppressor?
Amber, ochre, opal are mutated tRNAs that compete with the STOP tRNA for binding
Fix premature STOP
What’s a Frameshift suppressor?
The tRNA with codon CCCC that can pick up a G insertion to revert the reading frame
What’s a bypass suppressor?
Suppresses the need for an altered gene or pathway
Can act on one gene with multiple mutations or multiple mutated genes in the same pathway
Are bypass suppressors gene or allele specific?
Gene/pathway specific only
What does over-expression do and how?
Allows ordering of genes in a pathway
If the pathway reverts to WT, the over-expressed gene is downstream
What genes are informational suppressors?
Always tRNA genes
