Genetic Redundancy

David C Krakauer, Santa Fe Institute, Santa Fe, New Mexico, USA

Published online: July 2008

DOI: 10.1002/9780470015902.a0006116.pub2

Genetic redundancy typically relates to the duplication of an open reading frame within a genome. Genetic redundancy is often inferred when the modification or deletion of a portion of genetic material in a duplicated genome results in minimal changes in trait or organismal phenotype in reference to the nonduplicated wildtype. This invariance has been attributed to buffering mechanisms promoted by duplicates and to a number of compensatory pathways independent of the duplicate. Most duplicates are rapidly lost from genomes by mutation and drift.

Keywords: Robustness; canalization; genome architecture; evodevo; regulatory network; evolution

Figure 1. Convergent activation and nonspecific negative feedback can lead to functional redundancy in a gene regulatory network. Proteins A and B are transcription factors produced at an equal rate and capable of activating the expression of gene C. Gene A activates C at a rate ka and gene B activates C at a rate kb. Gene C can be thought to work according to three different negative feedback mechanisms: (1) encode a protein capable of inhibiting the production of A and B, (2) encode a protein inhibiting the activation of C by A and B or (3) increase the decay of A and B mRNA. In all three cases the inhibitory influence of C is given by the rate constant kc. All three proteins are degraded at an equal rate d. We are interested in the steady state concentration of C following the knockout of A in comparison with the steady state concentration of C in the wildtype (in which A and B are both present). The ratio of mutant to wild-type concentration of C assuming feedback mechanisms (1) and (2) is given by math . If we assume that ka=kb, then the reduction in steady state concentration of C is about 30%. The steady state ratio assuming feedback mechanism (3) depends on the rate of protein decay d. When the decay rate is very small (d0), then the ratio is equal to 1. In other words, the circuit is completely redundant with respect to the loss of A. When the decay rate is very fast (d¥) then for ka=kb, the ratio of mutant to wildtype is 0.5. For realistic rates of decay the ratio remains approximately equal to 1. This toy model shows that for a range of negative feedback mechanisms, this network structure produces a degree of functional redundancy greater than the additive contribution of individual genes.
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 Further Reading
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Related Sub-Topics:

Evolutionary Genomics | Molecular Evolution | Chromosomes and Chromatin Modifications | Evolution of Coding and Functional Modules
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Article Title: Genetic Redundancy
 
How to Cite close
Krakauer, David C(Jul 2008) Genetic Redundancy. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0006116.pub2]