TY  - JOUR
A1  - Mettler, Tabea
A1  - Mühlhaus, Timo
A1  - Hemme, Dorothea
A1  - Schöttler, Mark Aurel
A1  - Rupprecht, Jens
A1  - Idoine, Adam
A1  - Veyel, Daniel
A1  - Pal, Sunil Kumar
A1  - Yaneva-Roder, Liliya
A1  - Winck, Flavia Vischi
A1  - Sommer, Frederik
A1  - Vosloh, Daniel
A1  - Seiwert, Bettina
A1  - Erban, Alexander
A1  - Burgos, Asdrubal
A1  - Arvidsson, Samuel Janne
A1  - Schoenfelder, Stephanie
A1  - Arnold, Anne
A1  - Guenther, Manuela
A1  - Krause, Ursula
A1  - Lohse, Marc
A1  - Kopka, Joachim
A1  - Nikoloski, Zoran
A1  - Müller-Röber, Bernd
A1  - Willmitzer, Lothar
A1  - Bock, Ralph
A1  - Schroda, Michael
A1  - Stitt, Mark
T1  - Systems analysis of the response of photosynthesis, metabolism, and growth to an increase in irradiance in the photosynthetic model organism chlamydomonas reinhardtii
JF  - The plant cell
N2  - We investigated the systems response of metabolism and growth after an increase in irradiance in the nonsaturating range in the algal model Chlamydomonas reinhardtii. In a three-step process, photosynthesis and the levels of metabolites increased immediately, growth increased after 10 to 15 min, and transcript and protein abundance responded by 40 and 120 to 240 min, respectively. In the first phase, starch and metabolites provided a transient buffer for carbon until growth increased. This uncouples photosynthesis from growth in a fluctuating light environment. In the first and second phases, rising metabolite levels and increased polysome loading drove an increase in fluxes. Most Calvin-Benson cycle (CBC) enzymes were substrate-limited in vivo, and strikingly, many were present at higher concentrations than their substrates, explaining how rising metabolite levels stimulate CBC flux. Rubisco, fructose-1,6-biosphosphatase, and seduheptulose-1,7-bisphosphatase were close to substrate saturation in vivo, and flux was increased by posttranslational activation. In the third phase, changes in abundance of particular proteins, including increases in plastidial ATP synthase and some CBC enzymes, relieved potential bottlenecks and readjusted protein allocation between different processes. Despite reasonable overall agreement between changes in transcript and protein abundance (R-2 = 0.24), many proteins, including those in photosynthesis, changed independently of transcript abundance.
Y1  - 2014
U6  - https://doi.org/10.1105/tpc.114.124537
SN  - 1040-4651
SN  - 1532-298X
VL  - 26
IS  - 6
SP  - 2310
EP  - 2350
PB  - American Society of Plant Physiologists
CY  - Rockville
ER  - 
TY  - JOUR
A1  - Martins, Marina Camara Mattos
A1  - Hejazi, Mahdi
A1  - Fettke, Jörg
A1  - Steup, Martin
A1  - Feil, Regina
A1  - Krause, Ursula
A1  - Arrivault, Stephanie
A1  - Vosloh, Daniel
A1  - Figueroa, Carlos Maria
A1  - Ivakov, Alexander
A1  - Yadav, Umesh Prasad
A1  - Piques, Maria
A1  - Metzner, Daniela
A1  - Stitt, Mark
A1  - Lunn, John Edward
T1  - Feedback inhibition of starch degradation in arabidopsis leaves mediated by trehalose 6-phosphate
JF  - Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants
N2  - Many plants accumulate substantial starch reserves in their leaves during the day and remobilize them at night to provide carbon and energy for maintenance and growth. In this paper, we explore the role of a sugar-signaling metabolite, trehalose-6-phosphate (Tre6P), in regulating the accumulation and turnover of transitory starch in Arabidopsis (Arabidopsis thaliana) leaves. Ethanol-induced overexpression of trehalose-phosphate synthase during the day increased Tre6P levels up to 11-fold. There was a transient increase in the rate of starch accumulation in the middle of the day, but this was not linked to reductive activation of ADP-glucose pyrophosphorylase. A 2- to 3-fold increase in Tre6P during the night led to significant inhibition of starch degradation. Maltose and maltotriose did not accumulate, suggesting that Tre6P affects an early step in the pathway of starch degradation in the chloroplasts. Starch granules isolated from induced plants had a higher orthophosphate content than granules from noninduced control plants, consistent either with disruption of the phosphorylation-dephosphorylation cycle that is essential for efficient starch breakdown or with inhibition of starch hydrolysis by beta-amylase. Nonaqueous fractionation of leaves showed that Tre6P is predominantly located in the cytosol, with estimated in vivo Tre6P concentrations of 4 to 7 mu M in the cytosol, 0.2 to 0.5 mu M in the chloroplasts, and 0.05 mu M in the vacuole. It is proposed that Tre6P is a component in a signaling pathway that mediates the feedback regulation of starch breakdown by sucrose, potentially linking starch turnover to demand for sucrose by growing sink organs at night.
Y1  - 2013
U6  - https://doi.org/10.1104/pp.113.226787
SN  - 0032-0889
SN  - 1532-2548
VL  - 163
IS  - 3
SP  - 1142
EP  - 1163
PB  - American Society of Plant Physiologists
CY  - Rockville
ER  -