Proteomic analysis reveals contrasting stress response to uranium in two nitrogen-fixing Anabaena strains, differentially tolerant to uranium

•Response of two native cyanobacterial strains to uranium exposure was studied.•Anabaena L-31 exhibited higher tolerance to uranium as compared to Anabaena 7120.•Uranium exposure differentially affected the proteome profiles of the two strains.•Anabaena L-31 showed better sustenance of photosynthesis and carbon metabolism.•Anabaena L-31 displayed superior oxidative stress defense than Anabaena 7120.

Two strains of the nitrogen-fixing cyanobacterium Anabaena, native to Indian paddy fields, displayed differential sensitivity to exposure to uranyl carbonate at neutral pH. Anabaena sp. strain PCC 7120 and Anabaena sp. strain L-31 displayed 50% reduction in survival (LD50 dose), following 3 h exposure to 75 μM and 200 μM uranyl carbonate, respectively. Uranium responsive proteome alterations were visualized by 2D gel electrophoresis, followed by protein identification by MALDI-ToF mass spectrometry. The two strains displayed significant differences in levels of proteins associated with photosynthesis, carbon metabolism, and oxidative stress alleviation, commensurate with their uranium tolerance. Higher uranium tolerance of Anabaena sp. strain L-31 could be attributed to sustained photosynthesis and carbon metabolism and superior oxidative stress defense, as compared to the uranium sensitive Anabaena sp. strain PCC 7120.SignificanceUranium responsive proteome modulations in two nitrogen-fixing strains of Anabaena, native to Indian paddy fields, revealed that rapid adaptation to better oxidative stress management, and maintenance of metabolic and energy homeostasis underlies superior uranium tolerance of Anabaena sp. strain L-31 compared to Anabaena sp. strain PCC 7120.