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A discrete role for alternative oxidase under hypoxia to increase nitric oxide and drive energy production

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Title A discrete role for alternative oxidase under hypoxia to increase nitric oxide and drive energy production
 
Creator Vishwakarma, Abhaypratap
Kumari, Aprajita
Mur, Luis A.J.
Gupta, Kapuganti Jagadis
 
Subject alternative oxidase
nitric oxide
peroxynitrite
superoxide
energy efficiency
 
Description Accepted date: 26 March 2018
Alternative oxidase (AOX) is an integral part of the mitochondrial electron transport and can prevent reactive oxygen species (ROS) and nitric oxide (NO) production under non-stressed, normoxic conditions. Here we assessed the roles of AOX by imposing stress under normoxia in comparison to hypoxic conditions using AOX over expressing (AOX OE) and anti-sense (AOX AS) transgenic Arabidopsis seedlings and roots. Under normoxic conditions stress was induced with the defence elicitor flagellin (flg22). AOX OE reduced NO production whilst this was increased in AOX AS. Moreover AOX AS also exhibited an increase in superoxide and therefore peroxynitrite, tyrosine nitration suggesting that scavenging of NO by AOX can prevent toxic peroxynitrite formation under normoxia. In contrast, during hypoxia interestingly we found that AOX is a generator of NO. Thus, the NO produced during hypoxia, was enhanced in AOX OE and suppressed in AOX AS. Additionally, treatment of WT or AOX OE with the AOX inhibitor SHAM inhibited hypoxic NO production. The enhanced levels of NO correlated with expression of non-symbiotic haemoglobin, increased NR activity and ATP production. The ATP generation was suppressed in nia1,2 mutant and non symbiotic haemoglobin antisense line treated with SHAM. Taken together these results suggest that hypoxic NO generation mediated by AOX has a discrete role by feeding into the haemoglobin-NO cycle to drive energy efficiency under conditions of low oxygen tension.
KJG was funded by IYBA and Ramalingaswami fellowship fro Department of Biotechnology, Govt of India, AV was a recipient of National Postdoctoral Fellowship from SERB, Department of Science and Technology, Govt of India. We thank Debasis Chattopadhyay for providing flg22.Foot notes: KJG conceived original research plans. AV performed the experiment. LM provided AOX transgenics, AOX antibodies. KJG and LM prepared the manuscript.
 
Date 2018-03-28T09:15:27Z
2018-03-28T09:15:27Z
2018
 
Type Article
 
Identifier Free Radical Biology and Medicine, 122: 40-51
0891-5849
http://223.31.159.10:8080/jspui/handle/123456789/843
https://www.sciencedirect.com/science/article/pii/S0891584918301485
https://doi.org/10.1016/j.freeradbiomed.2018.03.045
 
Language en_US
 
Format application/pdf
 
Publisher Elsevier B.V.