Bacterial coexistence driven by motility and spatial competition
Sebastian Gude et al. | Nature 578, 588-592 (2020) | pdf & DOI
Processive extrusion of polypeptide loops by a Hsp100 disaggregase
Mario Avellaneda et al. | Nature 578, 317-320 (2020) | pdf & DOI
Alternative modes of client binding enable functional plasticity of Hsp70
Alireza Mashaghi et al. | Nature 539, 448-451 (2016) | pdf & DOI: 10.1038/nature20137
Stochasticity of metabolism and growth at the single-cell level
Daniel J. Kiviet et al. | Nature 514, 376-379 (2014) | pdf & DOI: 10.1038/nature13582
Reshaping of the conformational search of a protein by the chaperone trigger factor
Alireza Mashaghi et al. | Nature 500, 98-101 (2013) | pdf & DOI: 10.1038/nature12293
Tradeoffs and optimality in the evolution of gene regulation
Frank J. Poelwijk et al. | Cell 146, 462-470 (2011) | pdf & DOI:10.1016/j.cell.2011.06.035
Direct Observation of Chaperone-Induced Changes in a Protein Folding Pathway
Philipp Bechtluft, Ruud van Leeuwen et al. | Science 318:1458-1461 (2007) | pdf & DOI:10.1126/science.1144972
Empirical fitness landscapes reveal accessible evolutionary paths
Frank Poelwijk, Daan Kiviet et al. | Nature 445:383-386 (2007) | pdf & DOI:10.1038/nature05451
The bacteriophage phi29 portal motor can package DNA against a large internal force
Douglas E. Smith, Sander J. Tans et al. | Nature 413:748-52 (2001) | pdf & DOI:10.1038/35099581
Molecular transistors: Potential modulations along carbon nanotubes
Sander J. Tans, Cees Dekker. | Nature 404:834-35 (2000) | pdf & DOI:10.1038/35009026
Imaging electron wave functions of quantized energy levels in carbon nanotubes
Liesbeth C. Venema et al. | Science 283:52-55 (1999) | pdf & DOI:10.1126/science.283.5398.52
Electron-electron correlations in carbon nanotubes
Sander J. Tans et al. | Nature 394:761-64 (1998) | pdf & DOI:10.1038/29494
Room-temperature transistor based on a single carbon nanotube
Sander J. Tans, Alwin R. M. Verschueren & Cees Dekker | Nature 393:49-52 (1998) | pdf & DOI:10.1038/29954
Individual single-wall carbon nanotubes as quantum wires
Sander J. Tans et al. | Nature 386:474-77 (1997) | pdf & DOI:10.1038/386474a0
Fullerene 'crop circles'
Jie Liu et al. | Nature 385, 780-781 (1997) | pdf & DOI:10.1038/385780b0

Breaking evolutionary constraint with a tradeoff ratchet

de Vos, M. G.; Dawid, A.; Sunderlikova, V.; Tans, S. J.
Epistatic interactions can frustrate and shape evolutionary change. Indeed, phenotypes may fail to evolve when essential mutations are only accessible through positive selection if they are fixed simultaneously. How environmental variability affects such constraints is poorly understood. Here, we studied genetic constraints in fixed and fluctuating environments using the Escherichia coli lac operon as a model system for genotype-environment interactions. We found that, in different fixed environments, all trajectories that were reconstructed by applying point mutations within the transcription factor-operator interface became trapped at suboptima, where no additional improvements were possible. Paradoxically, repeated switching between these same environments allows unconstrained adaptation by continuous improvements. This evolutionary mode is explained by pervasive cross-environmental tradeoffs that reposition the peaks in such a way that trapped genotypes can repeatedly climb ascending slopes and hence, escape adaptive stasis. Using a Markov approach, we developed a mathematical framework to quantify the landscape-crossing rates and show that this ratchet-like adaptive mechanism is robust in a wide spectrum of fluctuating environments. Overall, this study shows that genetic constraints can be overcome by environmental change and that cross-environmental tradeoffs do not necessarily impede but also, can facilitate adaptive evolution. Because tradeoffs and environmental variability are ubiquitous in nature, we speculate this evolutionary mode to be of general relevance.
Type of Publication:
Proc. Natl. Acad. Sci. U.S.A.
[PubMed Central:\href{}{PMC4672788}] [DOI:\href{}{10.1073/pnas.1510282112}] [PubMed:\href{}{26567153}]
Hits: 430