title: Diazotrophic specific cytochrome c oxidase required to overcome light stress in the cyanobacterium Nostoc muscorum.
abstract: Diazotrophic, filamentous and heterocystous cyanobacterium Nostoc muscorum perform photosynthesis in vegetative whereas nitrogen fixation occurs in heterocyst only. However, despite their metabolic plasticity, respiration takes place both in vegetative cells and heterocysts. The role of the respiratory electron transport system and terminal oxidases under light stress is not evident so far. As compared to the diazotrophically grown cultures, the non-diazotrophically grown cultures of the N. muscorum show a slight decrease in their growth, chlorophyll a contents and photosynthetic O2 evolution under light stress. Whereas respiratory O2 uptake under identical stress condition increases several fold. Likewise, nitrogen fixing enzyme i.e. nitrogenase over-expresses itself under light stress condition. The terminal enzyme of respiratory electron transport chain i.e. cytochrome c oxidase shows more activity under light stress, whilst light stress has no impact on Ca(++)-dependent ATPase activity. This leads to the conclusion that under light stress, cytochrome c oxidase plays a vital role in mitigating given light stress.
authors.affiliation: Division of Microbiology, Department of Botany, Government Motilal Science College, Bhopal, M.P., 462008, India. santoshbhargava@hotmail.com.
authors.forename: Santosh
authors.initials: S
authors.lastname: Bhargava
authors.affiliation: Centre for Excellence in Biotechnology, M.P. Council of Science & Technology, Vigyan Bhavan, Nehru Nagar, Bhopal, M.P., India.
authors.forename: Shweta
authors.initials: S
authors.lastname: Chouhan
mesh_terms: D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D002734:Chlorophyll / Q000031:analogs & derivatives / Q000378:metabolism; D000077194:Chlorophyll A; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000378:metabolism*; D008027:Light; D009584:Nitrogen / Q000378:metabolism; D009586:Nitrogen Fixation; D009591:Nitrogenase / Q000378:metabolism; D050502:Nostoc muscorum / Q000201:enzymology* / Q000254:growth & development / Q000528:radiation effects; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis; D010860:Pigments, Biological / Q000378:metabolism; D013312:Stress, Physiological / Q000502:physiology*
chemical_list: D010860:Pigments, Biological; D002734:Chlorophyll; D002245:Carbon Dioxide; C085815:chlorophyll a'; D009591:Nitrogenase; D003576:Electron Transport Complex IV; D000252:Calcium-Transporting ATPases; D009584:Nitrogen; D010100:Oxygen; D000077194:Chlorophyll A
keywords: Ca++-dependent ATPase; Cyanobacteria; Cytochrome c oxidase; Diazotrophic; Light stress; Nostoc muscorum