Synthetic rescue (or synthetic recovery or synthetic viability when a lethal phenotype is rescued  ) refers to a genetic interaction in which a nonviable or sensitive to a specific drug due to the presence of a genetic mutation becomes viable when the original mutation is combined with a second mutation in a different gene.  The second mutation can be a loss-of-function mutation (equivalent to a knockout) or a gain-of-function mutation.  
Synthetic Reservoir could potentially be exploited for gene therapy , but it also provides information on the function of the genes involved in the interaction
Types of genetic suppression
Dosage-mediated suppression occurs when the suppression of the mutant phenotype is mediated by the over expression of a second gene suppressor. This can occur when the initial mutations destabilize the protein-protein interaction and the expression of the interacting protein bypass the negative effect of the initial mutation.
Interaction-mediated suppression occurs when a deleterious mutation in a component of a protein complex destabilizes the complex. A compensatory mutation in another component of the protein complex can then suppress the deleterious phenotype by re-establishing the interaction between the two proteins. It usually means that the deleterious mutation and the suppressive mutation occurs in two dimensions that are closely located in the three-dimensional structure of the multi-protein complex. Thus, this type of suppression provides indirect information on the molecular structure of the proteins involved.
Pathway bypass suppression
Genetic suppression can be mediated by tRNA genes when mutating their anticodon sequence. For example, a tRNA designated for the recognition of the TCA codon and the corresponding insertion of serine in the growing polypeptide chain can mutate so that it recognizes a TAA stop codon and promotes the insertion of serine instead of the termination of the polypeptide chain. This invention may be useful when a mutated mutation (TCA> TAA) prevents the expression of a gene expression or a partial transformation of the polypeptide or degradation of the mRNA by nonsense-mediated decay . The redundancy of tRNA genes makes sure that such mutation would not prevent the normal insertion of serines when the TCA codon specified them.
- Synthetic lethality
- Gene therapy
- Complex networks
- Suppressor mutation
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