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Molecular studies on structural changes and oligomerisation of violaxanthin de-epoxidase associated with the pH-dependent activation

Hallin, Erik Ingmar LU ; Hasan, Mahmudul LU ; Guo, Kuo LU and Åkerlund, Hans Erik LU (2016) In Photosynthesis Research 129(1). p.29-41
Abstract

Violaxanthin de-epoxidase (VDE) is a conditionally soluble enzyme located in the thylakoid lumen and catalyses the conversion of violaxanthin to antheraxanthin and zeaxanthin, which are located in the thylakoid membrane. These reactions occur when the plant or algae are exposed to saturating light and the zeaxanthin formed is involved in the process of non-photochemical quenching that protects the photosynthetic machinery during stress. Oversaturation by light results in a reduction of the pH inside the thylakoids, which in turn activates VDE and the de-epoxidation of violaxanthin. To elucidate the structural events responsible for the pH-dependent activation of VDE, full length and truncated forms of VDE were studied at different pH... (More)

Violaxanthin de-epoxidase (VDE) is a conditionally soluble enzyme located in the thylakoid lumen and catalyses the conversion of violaxanthin to antheraxanthin and zeaxanthin, which are located in the thylakoid membrane. These reactions occur when the plant or algae are exposed to saturating light and the zeaxanthin formed is involved in the process of non-photochemical quenching that protects the photosynthetic machinery during stress. Oversaturation by light results in a reduction of the pH inside the thylakoids, which in turn activates VDE and the de-epoxidation of violaxanthin. To elucidate the structural events responsible for the pH-dependent activation of VDE, full length and truncated forms of VDE were studied at different pH using circular dichroism (CD) spectroscopy, crosslinking and small angle X-ray scattering (SAXS). CD spectroscopy showed the formation of α-helical coiled-coil structure, localised in the C-terminal domain. Chemical crosslinking of VDE showed that oligomers were formed at low pH, and suggested that the position of the N-terminal domain is located near the opening of lipocalin-like barrel, where violaxanthin has been predicted to bind. SAXS was used to generate models of monomeric VDE at high pH and also a presumably dimeric structure of VDE at low pH. For the dimer, the best fit suggests that the interaction is dominated by one of the domains, preferably the C-terminal domain due to the lost ability to oligomerise at low pH, shown in earlier studies, and the predicted formation of coiled-coil structure.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
CD, Crosslinking, Oligomerisation, pH activation, SAXS, Violaxanthin de-epoxidase
in
Photosynthesis Research
volume
129
issue
1
pages
13 pages
publisher
Springer
external identifiers
  • scopus:84975784309
  • wos:000378411100004
ISSN
0166-8595
DOI
10.1007/s11120-016-0261-y
language
English
LU publication?
yes
id
0ae8b056-8225-4f9f-b16c-db4747706b01
date added to LUP
2016-07-08 11:54:02
date last changed
2017-05-28 04:50:59
@article{0ae8b056-8225-4f9f-b16c-db4747706b01,
  abstract     = {<p>Violaxanthin de-epoxidase (VDE) is a conditionally soluble enzyme located in the thylakoid lumen and catalyses the conversion of violaxanthin to antheraxanthin and zeaxanthin, which are located in the thylakoid membrane. These reactions occur when the plant or algae are exposed to saturating light and the zeaxanthin formed is involved in the process of non-photochemical quenching that protects the photosynthetic machinery during stress. Oversaturation by light results in a reduction of the pH inside the thylakoids, which in turn activates VDE and the de-epoxidation of violaxanthin. To elucidate the structural events responsible for the pH-dependent activation of VDE, full length and truncated forms of VDE were studied at different pH using circular dichroism (CD) spectroscopy, crosslinking and small angle X-ray scattering (SAXS). CD spectroscopy showed the formation of α-helical coiled-coil structure, localised in the C-terminal domain. Chemical crosslinking of VDE showed that oligomers were formed at low pH, and suggested that the position of the N-terminal domain is located near the opening of lipocalin-like barrel, where violaxanthin has been predicted to bind. SAXS was used to generate models of monomeric VDE at high pH and also a presumably dimeric structure of VDE at low pH. For the dimer, the best fit suggests that the interaction is dominated by one of the domains, preferably the C-terminal domain due to the lost ability to oligomerise at low pH, shown in earlier studies, and the predicted formation of coiled-coil structure.</p>},
  author       = {Hallin, Erik Ingmar and Hasan, Mahmudul and Guo, Kuo and Åkerlund, Hans Erik},
  issn         = {0166-8595},
  keyword      = {CD,Crosslinking,Oligomerisation,pH activation,SAXS,Violaxanthin de-epoxidase},
  language     = {eng},
  month        = {07},
  number       = {1},
  pages        = {29--41},
  publisher    = {Springer},
  series       = {Photosynthesis Research},
  title        = {Molecular studies on structural changes and oligomerisation of violaxanthin de-epoxidase associated with the pH-dependent activation},
  url          = {http://dx.doi.org/10.1007/s11120-016-0261-y},
  volume       = {129},
  year         = {2016},
}