Proteorhodopsin Phototrophy in Antarctic Coastal Waters

Abstract

Proteorhodopsin-bearing microorganisms in the Southern Ocean have been overlooked since their discovery in 2000. The present study identify taxonomy and quantify the relative abundance of proteorhodopsin-bearing bacteria and proteorhodopsin gene transcription in the West Antarctic Peninsula’s coastal waters.

Widespread use of proton-pumping rhodopsin in Antarctic phytoplankton

“…Because PPRs in bacteria colocalize with ATP (adenosine triphosphate) synthases and transporters in the same membrane surrounding the cell, the resulting proton gradient can then be used for membrane active transport, ATP synthesis and other cellular functions ( 2 , 7 ). Expression of proteorhodopsins (PRs) in bacterioplankton is common across different marine environments ( 8 , 9 ), including Antarctic coastal waters ( 10 ). Based on current evidence, bacterial PPRs may absorb as much light energy as photosynthetic light-harvesting complexes ( 11 ), yet it is unclear whether the membrane pH gradients generated by PPR light absorption are used primarily for ATP synthesis, as opposed to other physiological functions such as active membrane transport ( 7 , 12 , 13 ).…”