RC-LH1 core complex from R. palustris Neil Isaacs Department of Chemistry University of Glasgow.

RC-LH1 core complex from R. palustrisNeil Isaacs

Department of Chemistry

University of Glasgow

ATP synthase

ATPADP + Pi

H+

H+

H+

H+

LH2 LH1

RC

Light

Cyt c

Q

Q

Q

Q Q

Qe-

e-e-

B800

B850 B880

Cytochrome b/c1

Cytoplasm

Periplasm

QB

Q

Photosynthetic system of purple bacteria

Peripheral light-harvesting antenna (LH2 complex) from Rh. Acidophila, McDermott et al. (1995) Nature 374, 517.

Shown above is the structure of RC from Rhodobacter sphaeroides, Allen, et al. (1987) PNAS, 84, 5730; McAuley, et al. (1999) PNAS, 96, 14706.

First structure of reaction centre, from Rhodopseudomonas viridis, was determined by Deisenhofer, et al. (1985) Nature 318, 618.

The Bacterial Reaction Centre

Cytochrome bc1(Iwata et al (1998) Science, 281, 64—71)

F1ATPase Abrahams et al, (1994) Nature, 370, 621--8

ATP synthase

ATPADP + Pi

H+

H+

H+

H+

LH2 LH1

RC

Light

Cyt c

Q

Q

Q

Q Q

Qe-

e-e-

B800

B850 B880

Cytochrome b/c1

Cytoplasm

Periplasm

QB

Q

Karrasch et al. (1995) EMBO J., 14, 631.

Electron Microscopy 8.5 Å projection map for 2D-crystalof the reconstituted light-harvesting complex I (LH1) fromRhodospirillum rubrum.

Hypothetical model of the purple bacteria PSU

Papiz MZ, Prince SM, Hawthornthwaite-Lawles AM, McDermott G, Freer AA, Isaacs NW & Cogdell RJ (1996) Trends Plant Sci. 1, 198-206.

LH1

RC

LH2

Walz, et al. (1998) J. Mol. Biol. 282, 833.

Electron Microscopy 25 Å projections for 2D-crystals of the RC-LH1 complex from Rhodobacter sphaeroides.

Diffraction from crystals of the LH1-RC core complex

Current electron density map

QB

W

S. Bahatyrova et al, (2004) Nature, 430, 1058-1062

AFM shows the arrangement of photosynthetic complexes in the membrane

Questions to tax the brain:

What is protein W?

How does LH1 interact with RC?

How does W interact with RC and LH1?

How does the complex assemble?

34 proteins 2 Ubiquinone

19 Bchl 16? Carotenoid

2 Pheophytin Fe

> 70 components & no instructions….

LH60 column of Rps. palustris 'French' core complex

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 20 40 60 80 100 120

Fraction Number

Ab

sorb

an

ce (

280n

m)

RC polypeptides

LH polypeptidesPigments/phospholipids

W?

Separation of organic solvent soluble polypeptides

LH1-RC core

6.5

14

21 -dimers

-polypeptide

-polypeptide10

15

20

W?

6.5

14

21

SDS-PAGE of purified low-molecular weight LH polypeptides

The crystal structure of the RC LH1 core complex from

Rhodopseudomonas palustris

Aleksander W. Roszak, Tina D. Howard, June Southall, Alastair T. Gardiner, Neil W. Isaacs and Richard J. Cogdell

BBSRC Wellcome Trust

SRS Daresbury, stations14.1 and 9.6

Questions:What is protein W?

How does LH1 interact with RC?

How does W interact with RC and LH1?

How does the complex assemble?

34 proteins 2 Ubiquinone

19 Bchl 16? Carotenoid

2 Pheophytin Fe

> 70 components & no instructions….

Cytochrome bc1(Iwata et al (1998) Science, 281, 64—71)

F1ATPase Abrahams et al, (1994) Nature, 370, 621--8