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Abstract
Proteorhodopsin (PR) is a proton-pumping protein powered by light that can be used to generate energy, potentially powering ATP synthase. Transcripts for a PR-like gene have been isolated in some species of temperate and polar diatoms. A study investigating the distribution of the PR-like genes showed that they are mostly found in regions of the ocean that experience iron limitation. This suggests that the diatoms may use PR as a supplement to conventional photosynthesis during iron limitation. The following project uses physiological measurements and mass spectrometry-based quantitative proteomics to examine energy flow through the conventional photosynthetic system and compare it to energy flow through PR under varying levels of iron limitation. One PR containing diatom was studied alongside two non-PR containing diatoms for comparison. There was insufficient evidence to conclude that PR provided enough supplemental energy to increase the cellular energy budget of the PR containing diatom under iron limitation.