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Science. 2015 Feb 27;347(6225):1014-7. doi: 10.1126/science.1259145.

Evolution. Evolutionary resurrection of flagellar motility via rewiring of the nitrogen regulation system.

Author information

1
School of Biological Sciences, University of Reading, Whiteknights, Reading RG6 6AJ, UK.
2
Department of Biology, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA.
3
School of Biological Sciences, University of Reading, Whiteknights, Reading RG6 6AJ, UK. Department of Plant Production and Protection, Qassim University, Qassim, P.O. Box 6622, Saudi Arabia.
4
College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
5
Department of Biology, University of York, Wentworth Way, York YO10 5DD, UK.
6
School of Biological Sciences, University of Reading, Whiteknights, Reading RG6 6AJ, UK. l.j.johnson@reading.ac.uk.
7
School of Biological Sciences, University of Reading, Whiteknights, Reading RG6 6AJ, UK. The University of Akureyri, Borgir vid Nordurslod, IS-600 Akureyri, Iceland.

Abstract

A central process in evolution is the recruitment of genes to regulatory networks. We engineered immotile strains of the bacterium Pseudomonas fluorescens that lack flagella due to deletion of the regulatory gene fleQ. Under strong selection for motility, these bacteria consistently regained flagella within 96 hours via a two-step evolutionary pathway. Step 1 mutations increase intracellular levels of phosphorylated NtrC, a distant homolog of FleQ, which begins to commandeer control of the fleQ regulon at the cost of disrupting nitrogen uptake and assimilation. Step 2 is a switch-of-function mutation that redirects NtrC away from nitrogen uptake and toward its novel function as a flagellar regulator. Our results demonstrate that natural selection can rapidly rewire regulatory networks in very few, repeatable mutational steps.

PMID:
25722415
DOI:
10.1126/science.1259145
[Indexed for MEDLINE]
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