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Proteorhodopsins: an array of physiological roles?

Abstract

Metagenomic analyses have revealed widespread and diverse retinal-binding rhodopsin proteins (named proteorhodopsins) among numerous marine bacteria and archaea, which has challenged the notion that solar energy can only enter marine ecosystems by chlorophyll-based photosynthesis. Most marine proteorhodopsins share structural and functional similarities with archaeal bacteriorhodopsins, which generate proton motive force via light-activated proton pumping, thereby ultimately powering ATP production. This suggests an energetic role for proteorhodopsins. However, results from a growing number of investigations do not readily fit this model, which indicates that proteorhodopsins could have a range of physiological functions.

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Figure 1: Relative abundance of proteorhodopsin-containing bacteria.
Figure 2: Comparison of marine bacterial growth in light versus dark conditions.

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Acknowledgements

The authors thank J. Spudich and the anonymous reviewers for their helpful comments, especially on photoregulation and sensory rhodopsins, and D. Rusch for assistance with the GOS data and recalculating the percentage of PR versus recA. This work was supported by NSF Biological Oceanography and Microbial Observatory grants 0527034, 0648581 and 0703159.

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Correspondence to Jed A. Fuhrman.

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Fuhrman, J., Schwalbach, M. & Stingl, U. Proteorhodopsins: an array of physiological roles?. Nat Rev Microbiol 6, 488–494 (2008). https://doi.org/10.1038/nrmicro1893

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