AI Article Synopsis

  • The study investigates how UV radiation affects the fitness of the cyanobacterium PCC 7942 by assessing various genes involved in UV tolerance, emphasizing the need to identify specific genes that help these organisms survive in UV-rich environments.
  • Key findings point to crucial genes related to DNA repair, glutathione synthesis, and the function of photosystem II, as well as the unique role of a gene encoding leucyl aminopeptidase (LAP), which shows significant impact on UVR tolerance when disrupted.
  • The research highlights that LAP's function in glutathione catabolism is pH-sensitive and underreported under UV exposure, suggesting that similar LAP roles might be conserved in other organisms, offering insights into broader

Article Abstract

UV radiation (UVR) has significant physiological effects on organisms living at or near the Earth's surface, yet the full suite of genes required for fitness of a photosynthetic organism in a UVR-rich environment remains unknown. This study reports a genome-wide fitness assessment of the genes that affect UVR tolerance under environmentally relevant UVR dosages in the model cyanobacterium PCC 7942. Our results highlight the importance of specific genes that encode proteins involved in DNA repair, glutathione synthesis, and the assembly and maintenance of photosystem II, as well as genes that encode hypothetical proteins and others without an obvious connection to canonical methods of UVR tolerance. Disruption of a gene that encodes a leucyl aminopeptidase (LAP) conferred the greatest UVR-specific decrease in fitness. Enzymatic assays demonstrated a strong pH-dependent affinity of the LAP for the dipeptide cysteinyl-glycine, suggesting an involvement in glutathione catabolism as a function of night-time cytosolic pH level. A low differential expression of the LAP gene under acute UVR exposure suggests that its relative importance would be overlooked in transcript-dependent screens. Subsequent experiments revealed a similar UVR-sensitivity phenotype in LAP knockouts of other organisms, indicating conservation of the functional role of LAPs in UVR tolerance.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9659335PMC
http://dx.doi.org/10.1073/pnas.2211789119DOI Listing

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