Light-harvesting complex gene expression is controlled by both transcriptional and post-transcriptional mechanisms during photoacclimation in Chlamydomonas reinhardtii

2003 ◽  
Vol 118 (2) ◽  
pp. 193-205 ◽  
Author(s):  
Dion G. Durnford ◽  
Julie A. Price ◽  
Sarah M. McKim ◽  
Michelle L. Sarchfield
Keyword(s):  
Gene Expression ◽  
Chlamydomonas Reinhardtii ◽  
Light Harvesting ◽  
Light Harvesting Complex

Compartmental cross-talk in the regulation of light harvesting complex transcription under short-term light and temperature stress in Chlamydomonas reinhardtii

Botany ◽  
2009 ◽  
Vol 87 (4) ◽  
pp. 375-386 ◽  
Author(s):  
Penny L. Humby ◽  
Michelle L. Cunningham ◽  
Holly L. Saunders ◽  
Julie A. Price ◽  
Dion G. Durnford
Keyword(s):  
Gene Expression ◽  
Chlamydomonas Reinhardtii ◽  
Cross Talk ◽  
Redox State ◽  
Light Harvesting ◽  
Mitochondrial Activity ◽  
Short Term ◽  
Light Harvesting Complex ◽  
Photosynthetic Gene ◽  
Photosynthetic Production

Short-term light stress in Chlamydomonas leads to transient changes in light harvesting complex (LHC) transcription. This requires cross-talk between the plastid and nucleus to coordinate chloroplast function with nuclear transcription. None of the components of this signalling pathway have been identified although several sensor candidates have been proposed. To examine the regulation of nuclear photosynthetic gene expression, we constructed an LHC::Arylsulphatase (ARS) reporter system in Chlamydomonas reinhardtii allowing us to examine short-term regulatory changes on a fine scale. We modulated plastoquinone (PQ) redox state via photosynthetic inhibitors, changes in light and (or) temperature and found no evidence that either the PQ pool or QA redox state were directly involved in short-term retrograde signalling. Shifts in light level and (or) temperature indicated that LHC transcriptional activity is tightly coordinated to photosynthetic production. Transient switching between photoautotrophic and mixotrophic growth, plus the use of mitochondrial inhibitors indicated that nuclear photosynthetic gene expression is coupled to mitochondrial activity. These short-term effects on LHC transcription demonstrate an interdependence of photosynthetic production and mitochondrial activity, suggesting Chlamydomonas is able to respond to environmental changes by monitoring metabolite pools between the chloroplast and mitochondria and not in the chloroplast directly.

scholarly journals Identification of parallel pH- and zeaxanthin-dependent quenching of excess energy in LHCSR3 in Chlamydomonas reinhardtii

2020 ◽  
Author(s):  
Julianne M. Troiano ◽  
Federico Perozeni ◽  
Raymundo Moya ◽  
Luca Zuliani ◽  
Kwangryul Baek ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Light Harvesting ◽  
Complex Stress ◽  
Excess Energy ◽  
Photochemical Quenching ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex ◽  
Non Photochemical Quenching

AbstractUnder high light conditions, oxygenic photosynthetic organisms avoid photodamage by thermally dissipating excess absorbed energy, which is called non-photochemical quenching (NPQ). In green algae, a chlorophyll and carotenoid-binding protein, light-harvesting complex stress-related (LHCSR3), detects excess energy via pH and serves as a quenching site. However, the mechanisms by which LHCSR3 functions have not been determined. Using a combined in vivo and in vitro approach, we identify two parallel yet distinct quenching processes, individually controlled by pH and carotenoid composition, and their likely molecular origin within LHCSR3 from Chlamydomonas reinhardtii. The pH-controlled quenching is removed within a mutant LHCSR3 that lacks the protonable residues responsible for sensing pH. Constitutive quenching in zeaxanthin-enriched systems demonstrates zeaxanthin-controlled quenching, which may be shared with other light-harvesting complexes. We show that both quenching processes prevent the formation of damaging reactive oxygen species, and thus provide distinct timescales and mechanisms of protection in a changing environment.

scholarly journals Correlation between changes in light energy distribution and changes in thylakoid membrane polypeptide phosphorylation in Chlamydomonas reinhardtii.

1984 ◽  
Vol 98 (1) ◽  
pp. 1-7 ◽  
Author(s):  
F A Wollman ◽  
P Delepelaire
Keyword(s):  
Photosystem Ii ◽  
Chlamydomonas Reinhardtii ◽  
Redox State ◽  
Light Harvesting ◽  
Anaerobic Treatment ◽  
Intact Cells ◽  
Light Harvesting Complex ◽  
Plastoquinone Pool

We have used a new method to extensively modify the redox state of the plastoquinone pool in Chlamydomonas reinhardtii intact cells. This was achieved by an anaerobic treatment that inhibits the chlororespiratory pathway recently described by P. Bennoun (Proc. Natl. Acad. Sci. USA, 1982, 79:4352-4356). A state I (plus 3,4-dichlorophenyl-1,1-dimethylurea) leads to anaerobic state transition induced a decrease in the maximal fluorescence yield at room temperature and in the FPSII/FPSI ratio at 77 degrees K, which was three times larger than in a classical state I leads to state II transition. The fluorescence changes observed in vivo were similar in amplitude to those observed in vitro upon transfer to the light of dark-adapted, broken chloroplasts incubated in the presence of ATP. We then compared the phosphorylation pattern of thylakoid polypeptides in C. reinhardtii in vitro and in vivo using gamma-[32P]ATP and [32P]orthophosphate labeling, respectively. The same set of polypeptides, mainly light-harvesting complex polypeptides, was phosphorylated in both cases. We observed that this phosphorylation process is reversible and is mediated by the redox state of the plastoquinone pool in vivo as well as in vitro. Similar changes of even larger amplitude were observed with the F34 mutant intact cells lacking in photosystem II centers. The presence of the photosystem II centers is then not required for the occurrence of the plastoquinone-mediated phosphorylation of light-harvesting complex polypeptides.

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