title: Role of mrgA in peroxide and light stress in the cyanobacterium Synechocystis sp. PCC 6803.
abstract: In the unicellular cyanobacterium Synechocystis sp. PCC 6803, the mrgA gene is part of the PerR regulon that is upregulated during peroxide stress. We determined that an DeltamrgA mutant was highly sensitive to low peroxide levels and that the mutant upregulated a gene cluster (sll1722-26) that encoded enzymes involved with exopolymeric substance (EPS) production. We made mutants in this EPS cluster in both a wild type and DeltamrgA background and studied the responses to oxidative stress by measuring cell damage with LIVE/DEAD stain. We show that Synechocystis sp. PCC 6803 becomes highly sensitive to oxidative stress when either mrgA or the sll1722-26 EPS components are deleted. The results suggest that the deletion of the EPS cluster makes a cell highly susceptible to cell damage, under moderate oxidative stress conditions. Mutations in either mrgA or the EPS cluster also result in cells that are more light and peroxide sensitive, and produce significantly less EPS material than in wild type. In this study, we show that in the absence of MrgA, which is known to be involved in the storage or mobilization of iron, cells can be more easily damaged by exogenous oxidative and light stress.
authors.affiliation: University of Florida Space Life Science Lab, Department of Microbiology and Cell Science, Kennedy Space Center, FL 32899, USA.
authors.forename: Jamie S
authors.initials: JS
authors.lastname: Foster
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Havemann
authors.forename: Abhay K
authors.initials: AK
authors.lastname: Singh
authors.forename: Louis A
authors.initials: LA
authors.lastname: Sherman
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D008027:Light; D050296:Microbial Viability; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress; D010545:Peroxides / Q000494:pharmacology; D013194:Staining and Labeling / Q000379:methods; D013312:Stress, Physiological; D046939:Synechocystis / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D016877:Oxidants; D010545:Peroxides