Mechanism and regulation of the violaxanthin cycle: The role of antenna proteins and membrane lipids

Abstract

The violaxanthin cycle describes the reversible conversion of violaxanthin to zeaxanthin via the intermediate antheraxanthin. This light-dependent xanthophyll conversion is essential for the adaptation of plants and algae to different light conditions and allows a reversible switch of photosynthetic light-harvesting complexes between a light-harvesting state under low light and a dissipative state under high light. The photoprotective functions of zeaxanthin have been intensively studied during the last decade, but much less attention has been directed to the mechanism and regulation of xanthophyll conversion. In this review, an overview is given on recent progress in the understanding of the role of (i) xanthophyll binding by antenna proteins and of (ii) the lipid properties of the thylakoid membrane in the regulation of xanthophyll conversion. The consequences of these findings for the mechanism and regulation of xanthophyll conversion in the thylakoid membrane will be discussed.

Connection of the Photochemical Reflectance Index (PRI) with the Photosystem II Quantum Yield and Nonphotochemical Quenching Can Be Dependent on Variations of Photosynthetic Parameters among Investigated Plants: A Meta-Analysis

“…However, these photosynthetic parameters can be also affected by other mechanisms. In particular, different components of NPQ can be affected by the pH-dependent protonation of PsbS proteins [37,111], state transition [37,113,114], and photoinhibition [115]. The contribution of these processes to the total NPQ depends on environmental conditions [115,116] and the time of their development [117].…”

“…The effect may be due to the complex mechanisms of photosynthetic stress in plants. It is known that changes in PRI are mainly connected with redox processes in the xanthophyll cycle [26,36], which is regulated by pH in the lumen of chloroplasts [111]. Transitions in the xanthophyll cycle can influence the nonphotochemical quenching and the quantum yield of photosystem II [111,112].…”

Isolation and characterization of pigment deficient insertional mutants in the chlorophyte Chlamydomonas reinhardtii

“…The main short-time response in many higher plants and microalgae when transferred from low to high light intensity is the synthesis of zeaxanthin from violaxanthin through the xanthopyll cycle [33,34]. In Chlamydomonas this response to high light shifts is well documented [4].…”

“…The synthesis of zeaxanthin in Chlamydomonas cells after exposure to a high light stress [35] and other kind of stress conditions [36] has been previously reported. It has been demonstrated that this zeaxanthin is produced from violaxanthin via the xanthophyll cycle [33], but neither the enzyme nor the gene encoding this putative violaxanthin de-epoxidase (VDE) has been identified yet in Chlamydomonas. In the sequenced genome of this chlorophyte no orthologues to plant or other algal VDE genes have been identified [37].…”

Análise de pigmentos fotossintetizantes e substâncias fenólicas em Gracilariopsis tenuifrons (C. J. Bird & E. C. Oliveira) Fredericq & Hommersand em diferentes intensidades de luz

“…Essa diferença é a razão da incerteza quanto à presença funcional de um ciclo das xantofilas típico em algas vermelhas, ou da função destes pigmentos na dissipação térmica imediata, por exemplo. Por outro lado, trabalhos realizados em plantas terrestres têm indicado que a zeaxantina também pode ser encontrada livre nos tilacoides (Havaux et al, 2007;Jahns et al, 2009;, da mesma forma que nas membranas plasmáticas de cianobactérias que acumulam zeaxantina quando mantidas em alta intensidade de luz (Masamoto et al, 1999). Dessa forma, seria plausível propor que há duas localizações possíveis para zeaxantina, enquanto nas antenas haveria redução, fora das antenas poderia haver um aumento na concentração, assim a competição entre essas duas localizações poderia explicar o comportamento de aumento nos dias iniciais e redução nos dias finais.…”