Journal
FREE RADICAL BIOLOGY AND MEDICINE
Volume 161, Issue -, Pages 272-282Publisher
ELSEVIER SCIENCE INC
DOI: 10.1016/j.freeradbiomed.2020.10.015
Keywords
Magnetospirillum gryphiswaldense MSR-1; Magnetosomes; OxyR; Iron metabolism; Redox state
Funding
- Project for Extramural Scientists of the State Key Laboratory of Agrobiotechnology [2018SKLAB6-29]
- National Natural Science Foundation of China [31570067, 31860013]
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Magnetospirillum gryphiswaldense MSR-1 uses chains of magnetosomes, membrane-enveloped magnetite (Fe(II)Fe (III)(2)O-4) nanocrystals, to align along magnetic field. The process of magnetosome biomineralization requires a precise biological control of redox conditions to maintain a balanced amounts of ferric and ferrous iron. Here, we identified functions of the global regulator OxyR (MGMSRv2_4250, OxyR-4250) in MSR-1 during magnetosome formation. OxyR deletion mutant Delta oxyR-4250 displayed reduced magnetic response, and increased levels of intracellular ROS (reactive oxygen species). OxyR-4250 protein upregulated expression of six antioxidant genes (ahpC1, ahpC2, katE, katG, sodB, trxA), four iron metabolism-related regulator genes (fur, irrA, irrB, irrC), a bacterioferritin gene (bfr), and a DNA protection gene (dps). OxyR-4250 was shown, for the first time, to directly regulate magnetosome island (MAI) genes mamGFDC, mamXY, and feoAB1 operons. Taken together, our findings indicate that OxyR-4250 helps maintain a proper redox environment for magnetosome formation by eliminating excess ROS, regulating iron homeostasis and participating in regulation of Fe2+/Fe3+ ratio within the magnetosome vesicle through regulating MAI genes.
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