2026-04-22 ワシントン大学（UW）
In a new study, UW researchers explored why cells “stockpile” some proteins that are required for growth. Shown here is a series of “heat map” images that detail the abundance of a required protein over five bacterial generations — red represents more protein within the cell, while dark blue represents less. When the researchers disabled the gene necessary to make the protein, the abundance of that protein diminished in each generation (top row). The cells in the bottom row had a functioning gene, so the protein remained abundant. Photo: H. James Cho et. al/Science Advances
＜関連情報＞
- https://www.washington.edu/news/2026/04/22/paul-wiggins-protein-overabundance-study/
- https://www.science.org/doi/full/10.1126/sciadv.adz9623
タンパク質の過剰は成長の頑健性によって引き起こされる Protein overabundance is driven by growth robustness
H. James Choi, Teresa W. Lo, Kevin J. Cutler, Dean Huang, […] , and Paul A. Wiggins
Science Advances Published:20 Mar 2026
DOI:https://doi.org/10.1126/sciadv.adz9623
Abstract
Protein expression levels optimize cell fitness: Too low an expression level of essential proteins will slow growth by compromising essential processes, whereas overexpression slows growth by increasing the metabolic load. This trade-off naïvely predicts that cells maximize their fitness by sufficiency, expressing just enough of each essential protein for function. We test this prediction in the naturally competent bacterium Acinetobacter baylyi by characterizing the proliferation dynamics of essential-gene knockouts at a single-cell scale (by imaging) as well as at a genome-wide scale. In these experiments, cells proliferate for multiple generations as target protein levels are diluted from their endogenous levels. This approach facilitates a proteome-scale analysis of the fitness landscape with respect to protein abundance. We find that most essential proteins are subject to a threshold-like fitness landscape: Growth is independent of protein abundance above a critical threshold and arrests below that threshold. We have recently analyzed the implications of this landscape for growth robustness. Confirming signature predictions of this model, we find that (i) roughly 70% of essential proteins are overabundant, (ii) overabundance increases as the expression level decreases, and (iii) the lowest abundance proteins are in vast excess (>10×) of what is required for growth in the typical cell. These results reveal that robustness plays a fundamental role in determining the expression levels of essential genes and that overabundance is a key mechanism for ensuring robust growth.
