PHOTOSYNTHESIS: REACTION CENTERS & DIVERSITY IN ANTENNAES College Park, MD College Park, MD E. Gantt Cell Biol. & Molecular Genetics Oxygenic plants utilize the visible spectrum Origin of Photosynthesis Explored by: • Microfossils • Biomarkers • Genomics • Functional reconstitution Two Types of Photosynthesis of Same Origin? Anaerobic conditions in photosynthetic bacteria: heliobacteria, green sulfur, green non-sulfur and purple bacteria. Aerobic conditions in cyanobacteria, prochlorophytes, algae, and plants: oxygen from water oxidation. Evolution of Life Time-Frame Bill. Yr. Ago Time Events 4.5 BYA Origin of the earth 3.5-3.3 BYA Fossils resembling prokaryotes 2.8-2.5 BYA Biomarkers & cyanob. fossils 2.2-1.9 BYA Oxygen level rise 1.9-1.6 BYA Respiration level oxygen 1.5 BYA Cytoskeleton ancestral form? 1.2 BYA Eukaryote: Red algal fossil 0.6 BYA Land plant invasion, crown taxa Brown algae, dinoflag. fossils O2 CO2 (Modified after Green 2003) Biomineralized Microfossils (left) From O 2 -Evolved by Neoarchean Cyanobacteria (ca. 2.5 BYA) in Stromatolites (Kazmierczak.. Science, 2002, 298:2351) From: Tonga From: Poland Modern Morphological Evidence of Ancient Microfossils (3.46 MYA) Differentially Interpreted (Schopf et al. 2002 Nature 416:73) (Brasier et al. 2002 Nature 416:76) 3.46 2.1 0.77 .1 3.46
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PHOTOSYNTHESIS: REACTION CENTERS &
DIVERSITY IN ANTENNAES
College Park, MDCollege Park, MD
E. Gantt Cell Biol. & Molecular Genetics
Oxygenic plants utilize the visible spectrum
Origin of Photosynthesis Explored by:• Microfossils
• Biomarkers
• Genomics
• Functional reconstitution
Two Types of Photosynthesis of Same Origin?
Anaerobic conditions in photosynthetic bacteria:heliobacteria, green sulfur, green non-sulfur and purple bacteria.
Aerobic conditions in cyanobacteria, prochlorophytes, algae, and plants: oxygen from water oxidation.
Evolution of Life Time-Frame Bill. Yr. AgoTime Events
4.5 BYA Origin of the earth
3.5-3.3 BYA Fossils resembling prokaryotes
2.8-2.5 BYA Biomarkers & cyanob. fossils
2.2-1.9 BYA Oxygen level rise
1.9-1.6 BYA Respiration level oxygen
1.5 BYA Cytoskeleton ancestral form?
1.2 BYA Eukaryote: Red algal fossil
0.6 BYA Land plant invasion, crown taxa
Brown algae, dinoflag. fossilsO2
CO2
(Modified after Green 2003)
Biomineralized Microfossils (left) From O2-Evolved by Neoarchean Cyanobacteria (ca. 2.5 BYA) in Stromatolites
(Kazmierczak.. Science, 2002, 298:2351)
From:Tonga
From: Poland Modern
Morphological Evidence of Ancient Microfossils (3.46 MYA) Differentially Interpreted
(Schopf et al. 2002 Nature 416:73) (Brasier et al. 2002 Nature 416:76)
3.46
2.10.77.1
3.46
2
2-Methyl Hopanoid Biomarkers from Cyanobacteria: Consistent with Oxygenic Photosynthesis
(Summons et al. 1999 Nature 400:554)
Hopanoids-extant cyanobacteria
Hopanoids-petroleum sediments
Chloroflexu
s
Chlorobium
Heliobacte
rium
CyanobacteriaChloroplasts
Proteobacteria
16S rRNA Tree of Photosyn. Prokaryotes (Modified after Green 2003)
16S rRNA with RC types (Mod. Green 2003)
Chloro
flexus
Chlorobium
Heliobacterium
CyanobacteriaChloroplasts
Proteobacteria
Q
Q
Q
FeS
FeS
FeS
PHOTOSYNTHESIS ORIGIN? GENE DUPLICATION/ LATERAL TRANSFER
Ancestral RC(homodimeric, few antenna Chls)
LGT
Major Innovations:•Linear electron transport chain•H2O as electron donoraddition of Mn complex
Protocyanobacterial line
Gene duplication --> 2 cyclic PSs Proto-PSII loses FeS center
antenna-RC splitincrease in core antenna Chls
Cyanobacteria
?
FeS
Pre-protocyanobacterial line(homodimeric, more antenna Chls)
FeS
HeliobacteriaFeS
LGT:Bchl c synthesischlorosomes
Chlorobiaceae(homodimer, Bchl a)
FeS
QProto-PSII
PsaA PsaBFeS
Proto-PSIFeS
D1D2
Q CP43CP47
(Mod.from Green 2003)
Chloroflexaceae
Heterodimer-ization/ LGT
Proteobacteria
QL MLGT?
H2O O2Mn4
Interaction: PSII & PSI in Oxygenic Photosynthesis
RC2
Reductant
E’ 0
(vol
ts)
0.5
1.0
-1.0
-0.5
0 ETC
RC1
Strong reductant
NADP+
H20 O2
Concept of a Photosynthetic Unit
Originated from Emerson & Arnold 19321 Oxygen molec. per maximal light flash
with ca. 2000-3100 Chl participating
How realistic?- only Chl- assumes maximal conversion
3
Electron Transport Chain
Lumen
Stroma
(Kurisu et al., 2005 Science 302:124)
Photosystem 1 Reaction Center Complex
Buchanan et al Biochem..ASPB (2000)
PSI-trimer Synechocystis viewed from Stroma
(Jor
dan
et a
l.’01
Nat
ure
411
:909
)Synechocystis RC1 monomer stromal view
(Jor
dan
et a
l.’01
Nat
ure
411
:909
)
Periph-PsaAPeriph-PsaB
PSI RC:
PsaA, PsaB
Chl 96
Car 22
Fe-S clusters 3
Lipids 4 (plus ?)
Ca ion
(Ben-Shem et al. ’03 Nature 426:630)
cyano & pea
pea unique
pea
RCI Pea & Cofactors
4
Reaction Center 2
Buchanan et al Biochem..ASPB (2000)
1ps
200ps100-200us
Redox-reactive Components Note association of B-carotene Essential Component of Photosystem I and II Reaction Centers
PSII Core ComplexB-car
(Kamiya..2003, PNAS 100:98-103)
B-car
PS
II at
3A
, Lol
l et a
l. N
atur
e 20
05, 4
38: 1
040
PSII RC:
D1, D2 6 Chl
CP43 13 Chl
CP47 16 Chl
Cyt. 559
Cyt. 550
Car 11
Lipids 14
Heme 2
Mn cluster
Ca
(No. small prot.)
Pogson et al. 05,Photosy. II, Springer
Carotenoids functions in addition to accessory pigments
RC2RC1 RC2RC1
RC2RC1RC2RC1
RC2RC1
CYANOPHYTES RHODOPHYTES
CHLOROPHYTES CHROMOPHYTES
RC2RC1
DINOPHYTES CRYPTOPHYTES
Antenna Complexes and Reaction Centers
Ultrastructure of Leaf-chloroplast
Stroma
Thylakoids: Grana – PSII enrichedStromal –PSI enriched
CW
E. Gantt
Starch
5
LHC Antennae increase with Light Quantity Acclimation Photosystem RC1, RC2 in green Plants
Buchanan et al Biochem..ASPB (2000)
State Transition: Migration from PSII to PSI?
State I locked (thin) & State II locked (heavy)
(Takahashi et al. ’06 PNAS103:477)
680
700
State Transition: identification of light mobile elements
Phycobilisomes of Fremyella from red-light and green-light grown cells (Grossman et al. 2003)
Red-light (620 nm)Rod Core
Green-light (540 nm)Rod Core
Nostoc. Gantt
Regulators of Chromatic Acclimation
74 kD green-red ‘phytochrome’ type
73 kD
Sensor:
9
Model of CCA regulation:
Rca regulators &
Cgi system
(green light induction)
Phycobilisomes of Fremyella from red-light and green-light grown cells (Grossman et al. 2003) Two-component Regulators
Putative sensor for CCA
.
K
N
E
H
K
I
C LA G
F Y
PM
G G
LA
W D
V K F
R E
G R
M
A L
I
E I
G
A
V
E
P
M
K
M
AV
G
M
HL
Q
KL
SK
L
I
GI
V
FD
P
QN
PLL G
F DGP
E
M
I
K
W
TP
IA
KKS
IP
YFT E L N P L
KA V
AS T K
DMFV
A
SI
V
L F
Q
GA
KDS
FG
GL
M L
P
Y
P K TQA
L
LG
PP
DDF
A
V
G
GS D
K
NS
K KELFI
SM
N
ILL
PK
C
Stroma
Lumen
1 3
2L
R
Model of Lhca1 of P. cruentum, as influenced by the pea model of Green & Kühlbrandt (1994)Model of Lhca1 of P. cruentum, as influenced by the pea model of Green & Kühlbrandt (1994)
L
V
V
LL
E
K E S M F P I W S P EG
NS
.
..a4
a5
.a6
.a1
.a2
a3 a7
AVPV
G
R M
M EAI
A
KA
.a8
Rhodophyte LhcaR1 Model
Data: Gantt et al.
Phycobilisomes of Fremyella from red-light and green-light grown cells (Grossman et al. 2003) Operons
PS
II at
3A
, Lol
l et a
l. N
atur
e 20
05, 4
38: 1
040
Plastoquinone pocket
10
Cytochrome b6-f
(Kurisu et al., ‘03 Science 302:124 (Yan et al. ’06 PNAS 103: 69
Cytb6-f with quinone analog
HigherPlants
ChlorophytesGreen algae
RhodophytesRed algae
Euglenoids
Primaryendosymbiosis
Secondaryendosymbiosis
Chlorarachniophytes
Cyanobacterium
Photosyntheticeukaryote
Cryptophytes
Dinos.
Tertiary endosymbiosis
Chromophytes Browns, Diatoms
Chloroplast Origin Chloroplast Origin EndosymbiosisEndosymbiosis Hypothesis Hypothesis Summary of Photoreactions to Photophosporylation, note gain of 2 NADPH so far plus a high pH gradient
Becker et al. The World of the Cell
PSI Reaction Center: within the membrane planeN. Nelson 2003 Nature