Live Cell Chemical Profiling of Temporal Redox Dynamics in a Photoautotrophic Cyanobacterium

Protein
reduction–oxidation (redox) modification is an important
mechanism that allows microorganisms to sense environmental changes
and initiate cellular responses. We have developed a quantitative
chemical probe approach for live cell labeling and imaging of proteins
that are sensitive to redox modifications. We utilize this in vivo strategy to identify 176 proteins undergoing ∼5–10-fold
dynamic redox change in response to nutrient limitation and subsequent
replenishment in the photoautotrophic cyanobacterium Synechococcus sp. PCC 7002. We detect redox changes in as little as 30 s after
nutrient perturbation and oscillations in reduction and oxidation
for 60 min following the perturbation. Many of the proteins undergoing
dynamic redox transformations participate in the major components
for the production (photosystems and electron transport chains) or
consumption (Calvin–Benson cycle and protein synthesis) of
reductant and/or energy in photosynthetic organisms. Thus, our in vivo approach reveals new redox-susceptible proteins
and validates those previously identified in vitro.