Cellular signal transmission is not only optimized for precision—it also includes a cost cap. The relationship between information and energy, a concept well established in physics and engineering, is likely to fundamentally shape cellular signaling networks.
What enables reliable transmission of signals in the "noisy" cellular environment? The research team is studying signal transmission in baker's yeast (Saccharomyces cerevisiae), combining information theoretical approaches with quantitative experiments.
In biological systems, random fluctuations of signals always lead to background noise, which can impede cell communication. Organisms must therefore have developed strategies to improve the accuracy of signal transmission in the presence of such interference. However, little is yet known about how noise suppression is achieved in cellular networks.
That the pheromone signaling pathway of yeast contains negative feedback regulations could be seen as clear indication of selection for increased accuracy. Surprisingly, however, both theoretical and experimental analyses of the signaling pathway showed that its accuracy could be easily further improved by increasing the sensitivity of one of the negative feedbacks. So why this discrepancy between the potentially more efficient hypothetical and the natural design? In other words, why didn't yeast naturally optimize the system this way?
The answer seems to lie in the cellular economics. The discrepancy disappears when the energy investment in the operation of the signaling pathway is also considered. "We were able to show that the core of the MAPK signaling pathway, the phosphorylation cycle, has measurable fitness costs. When these are taken into account, and the accuracy of the signal transduction is weighed against the energetic costs of the signaling pathway operation, the naturally observed design appears optimal,"
cellular signaling에서 negative feedback 방식을 하면 더 효과적으로 반응한다고 한다. 하지만 그 방식을 잘 사용하지 않는데, 그 이유는 에너지가 더 많이 들기 때문이다.
reference
Alexander Anders et al, Design of a MAPK signaling cascade balances energetic cost versus accuracy of information transmission, Nature Communications (2020). DOI: 10.1038/s41467-020-17276-4