RT Journal Article SR Electronic T1 Repurposing a macromolecular machine: Architecture and evolution of the F7 chemosensory system JF bioRxiv FD Cold Spring Harbor Laboratory SP 653600 DO 10.1101/653600 A1 Davi R. Ortega A1 Poorna Subramanian A1 Petra Mann A1 Andreas Kjær A1 Songye Chen A1 Kylie J. Watts A1 Sahand Pirbadian A1 David A. Collins A1 Romain Kooger A1 Marina G. Kalyuzhnaya A1 Simon Ringgaard A1 Ariane Briegel A1 Grant J. Jensen YR 2019 UL http://biorxiv.org/content/early/2019/05/30/653600.1.abstract AB How complex, multi-component macromolecular machines evolved remains poorly understood. Here we reveal the evolutionary origins of the chemosensory machinery that controls flagellar motility in Escherichia coli. We first identified ancestral forms still present in Vibrio cholerae, Pseudomonas aeruginosa, Shewanella oneidensis and Methylomicrobium alcaliphilum, characterizing their structures by electron cryotomography and finding evidence that they function in a stress response pathway. Using bioinformatics, we then traced the evolution of the system through γ-Proteobacteria, pinpointing key evolutionary events that led to the machine now seen in E. coli. Our results suggest that two ancient chemosensory systems with different inputs and outputs (F6 and F7) existed contemporaneously, with one (F7) ultimately taking over the inputs and outputs of the other (F6), which was subsequently lost.