Redundancy in the Genetic Code Serves an Engineering Purpose
It’s not wasteful to keep multiple copies of genes
in the genome, a test of redundancy shows
At first glance, it appears wasteful. Why maintain multiple copies of a gene? E. coli bacteria have 7 copies of ribosomal RNA (rRNA) genes, and six copies each of transfer RNA (tRNA) genes. Why so many? There’s an energy cost to having to maintain and duplicate all those copies each time a cell divides. Is it bad design, or is there a reason for it?
The benefit of redundancy in biological systems (Max Planck Institute for Evolutionary Biology, 22 March 2023). The subtitle reads,
When viewed from an engineer’s perspective, biology is often messy and imperfect. For example, redundancy is a common feature of biological systems, with the job of one biological component overlapping with that of another. This work investigates whether some types of biological redundancy can – despite the apparent inefficiency – actually be beneficial.
Researchers in Germany and India silenced the duplicate copies of transfer RNAs in E. coli to see what happened. The results were beneficial in certain situations:
More gene copies are beneficial under increased translational demand
The growth profiles of all strains were measured across different environments, in which nutrient availability ranged from poor to rich. Generally speaking, the lower-redundancy strains grew faster than the original strain when nutrients were scarce, but slower than the original strain when nutrients were freely available …. These results are consistent with the initial hypothesis: genetic redundancy comes at a cost when translation is slow, and this cost is alleviated under conditions that support faster translation and growth.
This study has demonstrated that carrying multiple rRNA/tRNA gene copies can be beneficial under conditions that support increasingly faster translation and growth. More broadly, the results highlight that (apparent) redundancy can play a beneficial role in complex biological systems, particularly under changing environmental conditions.
Since “changing environmental conditions” are likely to be common in a bacterium’s environment, it looks like the better option is to prepare for large variations in nutrient availability by having more gene copies on hand.
Although the work was done at an institute for evolutionary biology, there was no other mention of evolution in the article. The scientists did not speculate that natural selection had discovered this principle or saw this from an “engineer’s perspective” like the researchers did.
God is a better engineer than evolutionists.
See my article about the cell as a factory of molecular machines (Evolution News, 30 May 2023).