The phytoglobin and nitric oxide cycle is a metabolic pathway that is induced in plants under conditions of oxygen deficiency and is an alternative to glycolytic fermentation . In this cycle, nitric oxide (NO) is metabolized with the participation of phytoglobin (Pgb) [1] . The cycle ensures the maintenance of the energy status of plants in conditions of limited access of oxygen [2] . Phytoglobin acts as a component of the terminal dioxigenase system in which a nitrate ion is formed as a result of the reaction of oxygenated phytoglobin with NO. Class 1 phytoglobins are induced in plants under hypoxic conditions, bind oxygen at nanomolar concentrations and can efficiently metabolize NO at cellular oxygen concentrations that are significantly lower than those required for the functioning of cytochrome c oxidase . During the reaction, phytoglobin is oxidized to metphytoglobin, which must be further reduced to ensure continuous operation of the cycle [3] [4] . Nitrate is reduced to nitrite by nitrate reductase , while NO is formed mainly due to anaerobic reduction of nitrite, which can occur in mitochondria using complex III and complex IV in the absence of oxygen, in the side reaction of nitrate reductase [5] or electron transport proteins on the plasma membrane [ 6] . The general sequence of cycle reactions leads to the oxidation of NADH and can help maintain ATP levels under conditions of deep hypoxia [7] . The functioning of the cycle explains the observation of B. B. Vartapetyan , that plant mitochondria under hypoxic conditions preserve ultrastructure in the presence of nitrate [8] .
Notes
- ↑ Igamberdiev AU, Baron K., Manac'h-Little N., Stoimenova M., Hill RD The haemoglobin / nitric oxide cycle: involvement in flooding stress and effects on hormone signalling (Eng.) // Annals of Botany : journal. - 2005. - Vol. 96 , no. 4 . - P. 557-564 . - DOI : 10.1093 / aob / mci210 . - PMID 16027133 .
- ↑ Gupta KJ, Igamberdiev AU The anoxic plant mitochondrion as a nitrite: NO reductase (English) // Mitochondrion: journal. - 2011. - Vol. 11 , no. 4 . - P. 537-543 . - DOI : 10.1016 / j.mito.2011.03.005 . - PMID 21406251 .
- ↑ Igamberdiev AU, Bykova NV, Hill RD Nitric oxide scavenging by barley hemoglobin is facilitated by a monodehydroascorbate reductase-mediated ascorbate reduction of methemoglobin (Eng.) // Planta: journal. - 2006. - Vol. 223 , no. 5 . - P. 1033-1040 . - DOI : 10.1007 / s00425-005-0146-3 . - PMID 16341544 .
- ↑ Jokipii-Lukkari S., Kastaniotis AJ, Parkash V., Sundström R., Leiva-Eriksson N., Nymalm Y., Blokhina O., Kukkola E., Fagerstedt KV, Salminen TA, Läärä E., Bülow L., Ohlmeier S., Hiltunen JK, Kallio PT, Häggman H. Dual targeted poplar ferredoxin NADP (+) oxidoreductase interacts with hemoglobin 1 // Plant Science : journal. - Elsevier , 2016 .-- Vol. 247 . - P. 138-149 . - DOI : 10.1016 / j.plantsci.2016.03.03.013 . - PMID 27095407 .
- ↑ Yamasaki H., Sakihama Y. Simultaneous production of nitric oxide and peroxynitrite by plant nitrate reductase: in vitro evidence for the NR-dependent formation of active nitrogen species (English) // FEBS Letters : journal. - 2000. - Vol. 468 , no. 1 . - P. 89-92 . - DOI : 10.1016 / S0014-5793 (00) 01203-5 . - PMID 10683447 .
- ↑ Stöhr C., Strube F., Marx G., Ullrich WR, Rockel P. A plasma membrane-bound enzyme of tobacco roots catalyses the formation of nitric oxide from nitrite (Eng.) // Planta: journal. - 2001. - Vol. 212 , no. 5-6 . - P. 835-841 . - DOI : 10.1007 / s004250000447 . - PMID 11346959 .
- ↑ Stoimenova M., Igamberdiev AU, Gupta KJ, Hill RD Nitrite-driven anaerobic ATP synthesis in barley and rice root mitochondria (Eng.) // Planta: journal. - 2007. - Vol. 226 , no. 2 . - P. 465-474 . - DOI : 10.1007 / s00425-007-0496-0 . - PMID 17333252 .
- ↑ Vartapetian BB, Polyakova LI Protective effect of exogenous nitrate on the mitochondrial ultrastructure of Oryza sativa coleoptiles under strict anoxia (Eng.) // Protoplasma. - 1999. - Vol. 206 , iss. 1-3 . - P. 163-167 . - ISSN 1615-6102 0033-183X, 1615-6102 . - DOI : 10.1007 / BF01279263 .