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Sugar beet hemoglobins : Reactions with nitric oxide and nitrite reveal differential roles for nitrogen metabolism

Eriksson, Nélida Leiva LU ; Reeder, Brandon J. ; Wilson, Michael T. and Bülow, Leif LU (2019) In Biochemical Journal 476(14). p.2111-2125
Abstract

In contrast with human hemoglobin (Hb) in red blood cells, plant Hbs do not transport oxygen, instead research points towards nitrogen metabolism. Using comprehensive and integrated biophysical methods we characterized three sugar beet Hbs: BvHb1.1, BvHb1.2 and BvHb2. Their affinities for oxygen, CO, and hexacoordination were determined. Their role in nitrogen metabolism was studied by assessing their ability to bind NO, to reduce nitrite (NiR, nitrite reductase), and to form nitrate (NOD, NO dioxygenase). Results show that BvHb1.2 has high NOD-like activity, in agreement with the high nitrate levels found in seeds where this protein is expressed. BvHb1.1, on the other side, is equally capable to bind NO as to form nitrate, its main... (More)

In contrast with human hemoglobin (Hb) in red blood cells, plant Hbs do not transport oxygen, instead research points towards nitrogen metabolism. Using comprehensive and integrated biophysical methods we characterized three sugar beet Hbs: BvHb1.1, BvHb1.2 and BvHb2. Their affinities for oxygen, CO, and hexacoordination were determined. Their role in nitrogen metabolism was studied by assessing their ability to bind NO, to reduce nitrite (NiR, nitrite reductase), and to form nitrate (NOD, NO dioxygenase). Results show that BvHb1.2 has high NOD-like activity, in agreement with the high nitrate levels found in seeds where this protein is expressed. BvHb1.1, on the other side, is equally capable to bind NO as to form nitrate, its main role would be to protect chloroplasts from the deleterious effects of NO. Finally, the ubiquitous, reactive, and versatile BvHb2, able to adopt ‘open and closed forms’, would be part of metabolic pathways where the balance between oxygen and NO is essential. For all proteins, the NiR activity is relevant only when nitrite is present at high concentrations and both NO and oxygen are absent. The three proteins have distinct intrinsic capabilities to react with NO, oxygen and nitrite; however, it is their concentration which will determine the BvHbs’ activity.

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author
organization
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type
Contribution to journal
publication status
published
subject
in
Biochemical Journal
volume
476
issue
14
pages
15 pages
publisher
Portland Press Limited
external identifiers
  • scopus:85070848942
  • pmid:31285352
ISSN
0264-6021
DOI
10.1042/BCJ20190154
language
English
LU publication?
yes
id
daf6e6a3-eb47-47e4-9961-e0075e8e200a
date added to LUP
2019-09-09 08:19:42
date last changed
2020-06-03 05:09:12
@article{daf6e6a3-eb47-47e4-9961-e0075e8e200a,
  abstract     = {<p>In contrast with human hemoglobin (Hb) in red blood cells, plant Hbs do not transport oxygen, instead research points towards nitrogen metabolism. Using comprehensive and integrated biophysical methods we characterized three sugar beet Hbs: BvHb1.1, BvHb1.2 and BvHb2. Their affinities for oxygen, CO, and hexacoordination were determined. Their role in nitrogen metabolism was studied by assessing their ability to bind NO, to reduce nitrite (NiR, nitrite reductase), and to form nitrate (NOD, NO dioxygenase). Results show that BvHb1.2 has high NOD-like activity, in agreement with the high nitrate levels found in seeds where this protein is expressed. BvHb1.1, on the other side, is equally capable to bind NO as to form nitrate, its main role would be to protect chloroplasts from the deleterious effects of NO. Finally, the ubiquitous, reactive, and versatile BvHb2, able to adopt ‘open and closed forms’, would be part of metabolic pathways where the balance between oxygen and NO is essential. For all proteins, the NiR activity is relevant only when nitrite is present at high concentrations and both NO and oxygen are absent. The three proteins have distinct intrinsic capabilities to react with NO, oxygen and nitrite; however, it is their concentration which will determine the BvHbs’ activity.</p>},
  author       = {Eriksson, Nélida Leiva and Reeder, Brandon J. and Wilson, Michael T. and Bülow, Leif},
  issn         = {0264-6021},
  language     = {eng},
  month        = {07},
  number       = {14},
  pages        = {2111--2125},
  publisher    = {Portland Press Limited},
  series       = {Biochemical Journal},
  title        = {Sugar beet hemoglobins : Reactions with nitric oxide and nitrite reveal differential roles for nitrogen metabolism},
  url          = {http://dx.doi.org/10.1042/BCJ20190154},
  doi          = {10.1042/BCJ20190154},
  volume       = {476},
  year         = {2019},
}