Functional and structural characterization of domain truncated violaxanthin de-epoxidase

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift

Abstract

Photosynthetic organisms need protection against excessive light. By using non-photochemical quenching, where the excess light is converted into heat, the organism can survive at higher light intensities. This process is partly initiated by the formation of zeaxanthin, which is achieved by the de-epoxidation of violaxanthin and antheraxanthin to zeaxanthin. This reaction is catalyzed by violaxanthin de-epoxidase (VDE). VDE consists of three domains of which the central lipocalin-like domain has been the most characterized. By truncating the domains surrounding the lipocalin-like domain, we show that VDE activity is possible without the C-terminal domain but not without the N-terminal domain. The N-terminal domain shows no VDE activity by itself but when separately expressed domains are mixed, VDE activity is possible. This shows that these domains can be folded separately and could therefore be studied separately. An increase of the hydrodynamic radius of wild-type VDE was observed when pH was lowered toward the pH required for activity, consistent with a pH-dependent oligomerization. The C-terminally truncated VDE did not show such an oligomerization, was relatively more active at higher pH but did not alter the KM for ascorbate. Circular dichroism measurements revealed the presence of α-helical structure in both the N- and C-terminal domains. By measuring the initial formation of the product, VDE was found to convert a large number of violaxanthin molecules to antheraxanthin before producing any zeaxanthin, favoring a model where violaxanthin is bound non-symmetrically in VDE.

Detaljer

Författare
Enheter & grupper
Forskningsområden

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Botanik
Originalspråkengelska
Sidor (från-till)414-421
Antal sidor8
TidskriftPhysiologia Plantarum
Volym157
Utgåva nummer4
Tidigt onlinedatum2016 feb 10
StatusPublished - 2016 aug 1
PublikationskategoriForskning
Peer review utfördJa

Relaterad forskningsoutput

Kuo Guo, 2017 nov, Lund: Lund University, Faculty of Science, Department of Chemistry, Division of Biochemistry and Structural Biology. 112 s.

Forskningsoutput: AvhandlingDoktorsavhandling (sammanläggning)

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Related projects

Kuo Guo & Hans-Erik Åkerlund

2013/09/302017/12/12

Projekt: Avhandling

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