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Linking chlorophyll biosynthesis to a dynamic plastoquinone pool.

Steccanella, Verdiana; Hansson, Mats LU and Jensen, Poul Erik (2015) In Plant Physiology and Biochemistry 97. p.207-216
Abstract
Chlorophylls are essential cofactors in photosynthesis. All steps in the chlorophyll pathway are well characterized except for the cyclase reaction in which the fifth ring of the chlorophyll molecule is formed during conversion of Mg-protoporphyrin IX monomethyl ester into Protochlorophyllide. The only subunit of the cyclase identified so far, is AcsF (Xantha-l in barley and Chl27 in Arabidopsis). This subunit contains a typical consensus di-iron-binding sequence and belongs to a subgroup of di-iron proteins, such as the plastid terminal oxidase (PTOX) in the chloroplast and the alternative oxidase (AOX) found in mitochondria. In order to complete the catalytic cycle, the irons of these proteins need to be reduced from Fe(3+) to Fe(2+) and... (More)
Chlorophylls are essential cofactors in photosynthesis. All steps in the chlorophyll pathway are well characterized except for the cyclase reaction in which the fifth ring of the chlorophyll molecule is formed during conversion of Mg-protoporphyrin IX monomethyl ester into Protochlorophyllide. The only subunit of the cyclase identified so far, is AcsF (Xantha-l in barley and Chl27 in Arabidopsis). This subunit contains a typical consensus di-iron-binding sequence and belongs to a subgroup of di-iron proteins, such as the plastid terminal oxidase (PTOX) in the chloroplast and the alternative oxidase (AOX) found in mitochondria. In order to complete the catalytic cycle, the irons of these proteins need to be reduced from Fe(3+) to Fe(2+) and either a reductase or another form of reductant is required. It has been reported that the alternative oxidase (AOX) and the plastid terminal oxidase (PTOX) utilize the di-iron center to oxidise ubiquinol and plastoquinol, respectively. In this paper, we have used a specific inhibitor of di-iron proteins as well as Arabidopsis and barley mutants affected in regulation of photosynthetic electron flow, to show that the cyclase step indeed is directly coupled to the plastoquinone pool. Thus, plastoquinol might act as an electron donor for the cyclase reaction and thereby fulfil the role of a cyclase reductase. That would provide a functional connection between the redox status of the thylakoids and the biosynthesis of chlorophyll. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Plant Physiology and Biochemistry
volume
97
pages
207 - 216
publisher
Elsevier
external identifiers
  • pmid:26480470
  • wos:000366950100022
  • scopus:84944673034
ISSN
1873-2690
DOI
10.1016/j.plaphy.2015.10.009
language
English
LU publication?
yes
id
236066b2-77ad-435e-8c44-7891c33c1301 (old id 8148969)
date added to LUP
2015-11-17 10:59:32
date last changed
2017-07-02 03:01:54
@article{236066b2-77ad-435e-8c44-7891c33c1301,
  abstract     = {Chlorophylls are essential cofactors in photosynthesis. All steps in the chlorophyll pathway are well characterized except for the cyclase reaction in which the fifth ring of the chlorophyll molecule is formed during conversion of Mg-protoporphyrin IX monomethyl ester into Protochlorophyllide. The only subunit of the cyclase identified so far, is AcsF (Xantha-l in barley and Chl27 in Arabidopsis). This subunit contains a typical consensus di-iron-binding sequence and belongs to a subgroup of di-iron proteins, such as the plastid terminal oxidase (PTOX) in the chloroplast and the alternative oxidase (AOX) found in mitochondria. In order to complete the catalytic cycle, the irons of these proteins need to be reduced from Fe(3+) to Fe(2+) and either a reductase or another form of reductant is required. It has been reported that the alternative oxidase (AOX) and the plastid terminal oxidase (PTOX) utilize the di-iron center to oxidise ubiquinol and plastoquinol, respectively. In this paper, we have used a specific inhibitor of di-iron proteins as well as Arabidopsis and barley mutants affected in regulation of photosynthetic electron flow, to show that the cyclase step indeed is directly coupled to the plastoquinone pool. Thus, plastoquinol might act as an electron donor for the cyclase reaction and thereby fulfil the role of a cyclase reductase. That would provide a functional connection between the redox status of the thylakoids and the biosynthesis of chlorophyll.},
  author       = {Steccanella, Verdiana and Hansson, Mats and Jensen, Poul Erik},
  issn         = {1873-2690},
  language     = {eng},
  pages        = {207--216},
  publisher    = {Elsevier},
  series       = {Plant Physiology and Biochemistry},
  title        = {Linking chlorophyll biosynthesis to a dynamic plastoquinone pool.},
  url          = {http://dx.doi.org/10.1016/j.plaphy.2015.10.009},
  volume       = {97},
  year         = {2015},
}