Fotosyntéza řas – regulace v průběhu denních cyklů

Fotosyntéza, řasy a Chromera velia
Laboratory of Photosynthesis – Algatech,
Institute of Microbiology, Třeboň
Academy of Sciences, Czech Republic
Fotosyntéza jako součást biologického cyklu uhlíku
účinnost přeměny zachycené energie ~ 30%
globálně 1.5x1014 W/rok ~ 150 000 jaderných elektráren
science.nationalgeographic.com
Fytoplankton: základní údaje
Průměr: < 1 m až > 100 m
Pokud naskládáte 1000 planktonních buněk o
velikosti 1 um vedle sebe, budou jako tlouštka
mince! (~18,000 buněk na šířku)
Koncentrace: 103 až 106 / ml
Pokud naplníte pivní láhev mořskou vodou v
době, kdy dochází k “vodnímu květu”, může
obsahovat i přes miliardu buněk!
Celková biomasa: < 1% celkové rostlinné biomasy na Zemi
ALE je zodpovědná za téměř polovinu čisté fotosyntézy celé biosféry!
Primary productivity of our planet
0
Productivity of all biosphere = 110 - 120 Gt C year-1
(annual anthropogenic emisisons 7.1 Gt C)
Hydrothermal vents ~ 0.01 Gt C year-1
Approx. 50% of productivity on land & 50% in oceans
50
100
Primary production (gC m-2 month-1)
(Giga = 109)
Chemosynthesis
hydrothermal vents on the bottom
of oceans ~ 0.01 Gt C year-1
Not every photosynthesis is about (bacterio)chlorophyl !
Halobacteria (archea): extremely halophilic (>4M NaCl)
proteins bacteriorhodopsin (pumps H+), halorhodopsin (Cl-)
forms membrane 2D crystals
Pigment - carotenoid retinal
Marine flavobacteria:
proteorhodopsin
discovered in 2000
13-80%
of all
marine
bacteria
Vývoj života a fotosyntézy
Miliardy let
Cévnaté
rostliny
Bezobratlí
Savci
Člověk
Vznik
Země
Řasy
Život
Makroskopická
eukaryota
Fototrofní
bakterie
Sinice a další
fototrofní organismy
Stromatolity
mikrofosilie
Vývoj života a fotosyntézy
Miliardy let
Cévnaté
rostliny
Bezobratlí
Savci
Člověk
Vznik
Země
Řasy
Život
Makroskopická
eukaryota
Fototrofní
bakterie
Sinice a další
fototrofní organismy
Milestones in the history of the Earth
Biomarkers for cyanos
and eukaryotes
Origin of Oxygenic PS
??
? ?
Rise of O2
Xiong and Bauer, 2002
Tree of life and photosynthesis
Photosynthetic
Prokaryotes
Diverse classes of antenna,
reaction center and electron
transfer complexes
Martin Hohmann-Marriott
Fylogenetické rozšíření oxygenních fotoautotrofů
druhově dominují
terestrické
(Embryofyta)
vodní prostředí
~30 tis. druhů
moře/sladkovodní
17/13 tis.
v mořích početně
sinice
druhově Bacillariofyta
Prochlorococcus
Endosymbiózy
primární
(~ 1.5 mld let)
sekundární
(~ 1.2 mld let)
terciární
Tree of life & eukaryotic diversity
Apicomplexa
Fehling et al., 2008
Plasmodium - contains relict plastid (apicoplast)
Apicoplast
© 2009 QIAGEN, all rights reserved
Nature 2007
Chromera velia
Plesiastrea versipora
Chromera velia – chlorophyll a (no chl c), symbiotic?
Apicomplexa
Alveolate evolution
Plasmodium falciparum
Toxoplasma gondii
Chromerida
Dinophyta
Moore et al., Nature 2007
Plesiastrea
versipora
Diversity of Chromerid algae
Phylum: Chromerida
 Different life cycle
 Different morphology
 Different plastid genome
Family: Vitrellaceae –
Vitrella brassicaformis
Janouškovec et al. PNAS 2010
Oborník et al. Protist 2012
Family: Chromeraceae –
Chromera velia
Oborník et al. Protist 2011
Chromera velia
Chromera velia
 Antennae organized as in Diatoms
Phaeodactylum
tricornutum
(Pan et al. Photosynth. Res. 2012)
Cyclotella
meneghiana
 Simple pigmentation asi in Eustigmatophytes
(Moore et al. Nature 2008)
Nannochloropsis sp.
 Primitive type II RuBisCO as in Dinoflagellates
Symbiodimum sp.
(Janouškovec et al. PNAS 2010)
 Heme synthesis as in Apicomplexans
(Kořený et. al Plant Cell 2011)
Plasmodium
falciparum
Toxoplasma
gondii
Heme biosynthesis pathway
• Two different ways of
5-Aminolevulinate (ALA)
synthesis
C4
C5
• Remaining 7 steps are
conserved among all
organisms
• Eukaryotes differ in the
origin of the genes and
intracellular localisation
of the enzymes
Chlorophyll Biosynthesis in Photosynthetic eukaryotes
• In the Photosynt. Cell, the
majority of the end-products
are needed in the Plastid
• Chlorophyll is synthesized in
much higher rate than the
Heme.
• Most Heme is used in the
Plastid for cytochromes and
for synthesis of Bilin
Chromophores
• Only small portion of the
heme is needed in mitochondrion for respiratory
complexes
Heme Biosynthesis in Apicomplexa
Apicoplast
• Similarly to secondary algae, some
genes come from the plastid
• However, it uses δ-aminolevulinate synthase and localization
resembles more the primary
heterotrophs
Tetrapyrrole biosynthesis in Chromera velia?
• Data from 454 genome sequencing – small reads
• Search for Sequences homologous to Heme genes
• Full-length cDNA amplification by RACE
• Phylogenetic analyses
• Targeting Predictions
Kořený et al. 2011. Plant Cell
Tetrapyrrole biosynthesis in Chromera velia
HETEROTROPH
PRIMARY ALGA
Chromera
Apicomplexa
+
Kořený et al. 2011. Plant Cell
Tetrapyrrole biosynthesis in Chromera velia
C14
• 14C Glycine and Glutamate were used to
C14
discriminate between the two ways of
ALA synthesis
• Chlorophyll was subsequently extracted,
converted into chlorin and separated on
TLC plate
• Synechocystis was used as a control
organism that uses glutamate for ALA
synthesis
Chlorophyll a
Chlorin e6
C14
Kořený et al. 2011. Plant Cell
Tetrapyrrole biosynthesis in Chromera velia
Kořený et al. 2011. Plant Cell
Tetrapyrrole biosynthesis in chromalveolates
Kořený et al. 2011. Plant Cell
Enzyme RuBisCO
Form II
dimer of large subunits (L2)n
 lacks small subunits
 low Srel value - low discrimination against O2 as an alternative substrate
 poor affinity for CO2
 relatively high kcat

Form II enzyme is adapted to functioning in low-O2 and high-CO2 environments.
Badger et al. J. Exp. Bot. 2008
Photosynthesis under
day/night cycle
Oxygen evolution



Very high photosynthetic rates - 4-5 times
higher than those measured in cultures
receiving continuous light
High rate of carbon fixation – due to type II
of enzyme RuBisCO (high kcat)
Type II RuBisCO is very sensitive to presence
of O2 (Srel )
Carbon fixation
There must be a mechanism that reduces O2
accessibility to RuBisCO.

Carbon a
Hysteresis effect - mid-morning maximum
and afternoon depression
Photosynthetic rates
cyclic electron flow
photorespiration
Photorespiration
Oxygen produced
CO2 assimilated
Photorespiration in C. velia –
mechanism for energy dissipation
(photoprotection).
~ 1,3
Dinoflagellates
Summary
Apicomplexa
Plasmodium falciparum
Symbiodinium sp.
Chromerida
Chromera velia
Eustigmatophyceae
Nannochloropsis limnetica
Diatoms
Phaeodactylum tricornutum
Acknowledgements
Eva Kotabová
Jana Jarešová
Radek Kaňa
Barbora Hošková
Jiří Šetlík
Jana Hofhanzlová
Antonietta Quigg (Texas A&M,
USA)
Luděk Kořený
Roman Sobotka
Jan Janouškovec
Patrick J. Keeling (UBC,
Canada)
Miroslav Oborník
This project is supported by:
GAAV IAA601410907 (2009-12)