Phototrophs trade growth for defense through graded regulatory states under escalating oxidative stress
Abstract
Oxygenic phototrophs face a paradox: the reactions powering growth generate oxidative stress, whose damage or costly defense reduces fitness. In Synechococcus elongatus PCC 7942, we profiled steady-state growth, photophysiology, and transcription across a dissolved oxygen gradient (0-374% air saturation). Independent component analysis of these transcriptomes within a 407-sample compendium resolved 78 regulatory modules (iModulons) explaining 72.3% of variance. Growth rate followed a graded, sigmoidal dose-response, which we divide into low, moderate, and severe stress regimes (14% and 47% decline, then arrest). Stress-responsive module activities shifted across these regimes: low stress activated SufR and PerR at minimal growth cost; moderate stress modulated three RpaB states, then ManR, CopR, and Rre1; and severe stress triggered a dual-control checkpoint with a fourth RpaB state linking redox sensing to the stringent response and growth arrest. Protein oxidation, pigments, and energy transfer tracked these transitions, suggesting cells trade growth for defense through discrete regulatory states.
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BibTeX
@article{johnson2026phototrophs,
title = {{Phototrophs trade growth for defense through graded regulatory states under escalating oxidative stress}},
author = {Zachary Johnson and Natalie C. Sadler and Marci Garcia and Ashley Gilliam and Eric Allen Hill and Xiaolu Li and Jesse B. Trejo and Wei-Jun Qian and Margaret S. Cheung and Pavlo Bohutskyi},
journal = {iScience},
year = {2026},
month = oct,
doi = {10.1016/j.isci.2026.117861},
url = {https://www.cell.com/iscience/fulltext/S2589-0042(26)03242-6},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Phototrophs trade growth for defense through graded regulatory states under escalating oxidative stress
AU - Zachary Johnson
AU - Natalie C. Sadler
AU - Marci Garcia
AU - Ashley Gilliam
AU - Eric Allen Hill
AU - Xiaolu Li
AU - Jesse B. Trejo
AU - Wei-Jun Qian
AU - Margaret S. Cheung
AU - Pavlo Bohutskyi
PY - 2026
DA - 2026/10/14
JO - iScience
DO - 10.1016/j.isci.2026.117861
UR - https://www.cell.com/iscience/fulltext/S2589-0042(26)03242-6
AB - Oxygenic phototrophs face a paradox: the reactions powering growth generate oxidative stress, whose damage or costly defense reduces fitness. In Synechococcus elongatus PCC 7942, we profiled steady-state growth, photophysiology, and transcription across a dissolved oxygen gradient (0-374% air saturation). Independent component analysis of these transcriptomes within a 407-sample compendium resolved 78 regulatory modules (iModulons) explaining 72.3% of variance. Growth rate followed a graded, sigmoidal dose-response, which we divide into low, moderate, and severe stress regimes (14% and 47% decline, then arrest). Stress-responsive module activities shifted across these regimes: low stress activated SufR and PerR at minimal growth cost; moderate stress modulated three RpaB states, then ManR, CopR, and Rre1; and severe stress triggered a dual-control checkpoint with a fourth RpaB state linking redox sensing to the stringent response and growth arrest. Protein oxidation, pigments, and energy transfer tracked these transitions, suggesting cells trade growth for defense through discrete regulatory states.
SN - 2589-0042
ER -