Nitric Oxide (NO) and its associated reactive nitrogen species (RNS) produce nitrosative stress under various pathophysiological conditions in eukaryotes. The fission yeast Schizosaccharomyces pombe regulates stress response mainly through the Sty1-Atf1 MAP Kinase pathway. The present study deals with the role of transcription factor Atf1 and Sty1 in S. pombe under nitrosative stress. In this study, exposure to an NO donor resulted in S-phase slowdown with associated mitotic block in S. pombe. Deletion of sty1 and atf1 in S. pombe had differential growth sensitivity towards NO donor. Both Sty1 and Atf1 were involved in regulating mitotic slowdown in S. pombe under nitrosative stress. Experimental data obtained in this study reveals a novel role of Atf1 in initiating the replication slowdown in S. pombe under nitrosative stress. Both Sty1 and Atf1 were accumulated in the nucleus in S. pombe under nitrosative stress in a concentration and time dependent manner. Atf1 is also found to be nuclear delocalized under longer nitrosative stress.

Nitric oxide (NO) acts as a signalling molecule that has direct and indirect regulatory roles in various functional processes in biology, though in plant kingdom its role is relatively unexplored. One reason for this is the fact that sensing of NO is always challenging. There are very few probes that can classify the different NO species. The present paper proposes a simple but straightforward way for sensing different NO species using chlorophyll, the source of inspiration being hemoglobin that serves as NO sink in mammalian systems. The proposed method is able to classify NO from DETA-NONOate or (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl) amino] diazen-1-ium-1,2-diolate, nitrite, nitrate and S-nitrosothiol or SNO. This discrimination is carried out by chlorophyll a (chl a) at nano molar (nM) order of sensitivity and at 293 K-310 K. Molecular docking reveals the differential binding effects of NO and SNO with chlorophyll, the predicted binding affinity matching with the experimental observation. Additional experiments with a diverse range of cyanobacteria reveal that apart from the spectroscopic approach the proposed sensing module can be used in microscopic inspection of NO species. Binding of NO is sensitive to temperature and static magnetic field. This provides additional support for the involvement of the porphyrin ring structures to the NO sensing process. This also, broadens the scope of the sensing methods as hinted in the text.

No abstract

Nitric oxide (NO) acts as a signalling molecule that has direct and indirect regulatory roles in various functional processes in biology, though in plant kingdom its role is relatively unexplored. One reason for this is the fact that sensing of NO is always challenging. There are very few probes that can classify the different NO species. The present paper proposes a simple but straightforward way for sensing different NO species using chlorophyll, the source of inspiration being hemoglobin that serves as a NO sink in most mamalian system. The proposed method is able to classify NO from DETA-NONOate or (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl) amino] diazen-1-ium-1,2-diolate, nitrite, nitrate and S-nitrosothiol or SNO. This discrimination is carried out by chlorophyll a (chl a) at nano molar (nM) order of sensitivity and at 293K to 310K. Molecular docking reveals the differential binding behaviour of NO and SNO with chlorophyll, the predicted binding affinity matching with the experimental observation. Additional expreiments with diverse range of cyanobacteria reveals that apart from spectroscopic approach the proposed sensing module can be used in microscopic inspection of NO speices. Binding of NO is sensitive to tempertaure and static magnetic field. This provides additional support to the involvement of the porphyrin ring structure to the NO sensing process. This

No abstract