1

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

(Takahashi et al. ’06 PNAS103:477)

Identification of light mobile elements

(Takahashi et al. ’06 PNAS103:477)

Chlamydomonas LHCs Part of a Multigene Family

(Takahashi et al. ’06 PNAS 103:477)

Antenna Pigments of Major Algal Classes

__________________________________________________

Cyanophytes Chl a apc, pc, pe

Chlorophytes Chl a, b - lut, vio, neo

(sipho)

Rhodophytes Chl a, (d) apc, pc, pe

Chromophytes Chl a, c - fuco, dia, dino

Cryptos Chl a, c pc, pe allo

Dinophytes Chl a, c - per, dia

Prochlorophytes

6

LHCI Antenna in Reds: Common LHCI Antenna in Reds: Common Origin of LHCs of Varied Pigments?Origin of LHCs of Varied Pigments?

G.R. Wolfe

(Wolfe, et al. 1994 Nature 367:566)

PSI Holocomplex = 135-150 Chl/P700

PSI Core = 98 Chl/P700 , -carotene

LHC I = 35-50 Chl, Zeaxanthin

S. Tan

B. Green

D. Durnford

21Kd

30Kd

14Kd

Anti-Barley Anti-Diatom

PorphThyl

PorphPSI H

Spinach Thyl

PorphThyl

PorphPSI H

Spinach Thyl

Native & Reconst. LHC Complex of Native & Reconst. LHC Complex of Porphyridium: Porphyridium: Energy TransferEnergy Transfer

AB

SOR

BA

NC

E RELA

TIVE INTEN

SITY

LHCIrLHCaR1

Chl a

6771.0

0.8

0.6

0.4

0.20.0

400 480 560 640 660 680 730 780WAVELENGTH (nm)

Car

Chl a

(2000 Phot Res 63:85

B. Grabowski

LHCaR1

Functional Reconstitution with Pigments of:Functional Reconstitution with Pigments of:

Spinach (Spinacea) Diatom (Thallasiosira)

Wavelength (nm)(Grabowski et al. 2001 PNAS 98:2911)

Pigment Insertion Into Simple Red Algal Pigment Insertion Into Simple Red Algal Protein Crosses Phylogenetic LinesProtein Crosses Phylogenetic Lines

Pigments/PolypeptideRhodo. Chloro. Chromo.

Chl a 8.2 6.2 7.0Chl b - 1.8 -Chl c - - 1.0

Zea 4.0 - -Lut - 2.4 -Neo - 0.7 -Vio - 1.2 -Fuc - - 8.0Diadin - - 1.9(<0.5 not included)

Wavelength (nm)

Chlorophyllsd

a

Abs

orba

nce

b

c1

Abs

orba

nce

lutein B-PE PC APC

700650600550500450400

Photosynthetic Pigments: Where & How? Photosynthetic Pigments: Where & How? PorphyridiumPorphyridium Photosystem ComplexesPhotosystem Complexes

Gantt - DOE Supporte

7

M N

What Are Those What Are Those 'Granules' in the 'Granules' in the Chloroplast of Chloroplast of PorphyridiumPorphyridium??

Are They Found in Are They Found in Other Other

Chloroplasts?Chloroplasts?

(1965 JCB 26:365)

Visual Ident. Followed by PBS IsolationVisual Ident. Followed by PBS Isolation

(1966 JCB 29:423)

Red pellet

Green pellet

Purple pellet

P

G

R

Major Major P. cruentumP. cruentum PBS PigmentsPBS Pigments

(1974 Biochem 13:2960)

B-PE

b-PE

R-PCAPC

Abs. Fluor.678

J. GrabowskiEnergy Transfer (FEnergy Transfer (Föörster Type): rster Type): Fluorescence Lifetimes, Quantum Fluorescence Lifetimes, Quantum Yields, & Polarized Spectra Yields, & Polarized Spectra

hv

PEF575 > PCF640 > APCF660nm > ? >Chl?(1978 Phot Phot 28:47)

C. Lipschultz

(1976 BBA 430:375)

?

PBS: Phycobiliprotein PBS: Phycobiliprotein Release PE>PC>APCRelease PE>PC>APC

PBS Pigment Location by ImmunoPBS Pigment Location by Immuno--FerretinFerretin

Anti-PE: ++++ + ---

Anti-PC: --- +++ +

Anti-APC: --- + +++(1977 J Phycol 13:185)

8

M. MimuroLLCMCM (F(F682682) is Terminal PBS Emitter ) is Terminal PBS Emitter

PEF575 > PCF640 > APCF660nm >LCMF682 >? Chl

(1986 BBA852:126)

PEF575 > PCF640 > APCF660 > LCM682 > Chl

PIIPII--PBSPBS ParticleParticle IsolationIsolation T. Katoh

(1983 FEBS Lett 156:185)

J. Clement-Metral

695 nm irradiated

665 nm irradiated

545 nm irradiated

ųM O

2/mg

Chl

-h

(1985 Plant Phys 77:626)

PIIPII--PBS Particle Evolve OPBS Particle Evolve O22 Chromatic acclimation

Regulation to light quality

• HOW COMMON?

• WHERE DOES IT OCCUR?

• HOW IS IT REGULATED?

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