Oxygen

• “Permanent” burial of organic matter on cratons

• Continuous coupling of C/N/O (and S) redox reactions – never an equilibrium state for the planet

• Requires liquid water on the surface of the planet

The evolution of nannomachines

The fundamental problem in origins of life - evolution of energy

transduction before information? Or vice versa?

Transmission microscope picture of NPP1

Electron sources: Photosynthesis and respiration

Model of bacterial reaction center in Ro. denitrificans (modified from Takamia, 1989)

IRFRR fluorescence transient

Light utilization and carbon fixation – these bugs are photoheterotrophs (a “dual fuel” metabolic strategy}

Wavelength [nm]400 500 600 700 800 900Absorbance (a.u.), 875 nm EM (a.u.),

and quantum efficiency

0.0

0.2

0.4

0.6

0.8

1.0Absorbance

Emission at 875 nm x 4

QuantumEfficiency

Irradiance [μmol quanta m-2s-1]

0 200 400 600 800 1000 1200( 2) ( )mmol CO fixed mol BChla

-1 s-1

4

6

8

10

12

14

16

18

electrons RC

-1 s-1

0

10

20

30

40

50

60

CO2 fixedElectron transportrate

PSII type Reaction Center

The Mn cluster in PS II

Frozen metabolic accidents

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

PsaCPsbAAtpHPsbDPetBPsbFAtpBRbcLPsaBPsbLPetDAtpAPsaAPsbCPsbBPsaEPetGPsbKAtpIPsbEPetCPetHAtpCPetAPsaDPsbHAtpEPsbJPetFPsaMPsbWPsbNPsaLAtpDPsbOAtpGAtpFPsbPPsbX

mutation rate (substitution/site/OTU)

proteins in all chloroplasts

proteins in at least one but not all chloroplasts

proteins in nucleus only

PS genes retained in chloroplasts are very highly conserved

34S sulfate 34S sulfide 33S

-50

-25

0

25

50

0 1 2 3 4 5

Age (Ga)

34S

-10

-5

0

5

10

33S

NitrogenaseNitrogenase

Chronically Crippled Nitrogenase

0

50

100

150

200

250

300

350

0 5 20 50

Oxygen concentration (% in air)

% nitrogenase activity from

control

Northern - nifH

Westerns-Fe-protein

Oxygen concentration (% in air)

0 5 20 50

Nitrogenase activity

0

50

100

150

200

250

300

350

0 5 20 50

Oxygen concentration (% in air)

% nitrogenase activity from

control

Northern - nifH

Westerns-Fe-protein

Oxygen concentration (% in air)

0 5 20 50

Nitrogenase activity

Anabaena sp.

H2 or C-mediated

Photosynthesis

O2

Mn4+

NO3-

N2

Fe3+

SO42-

CO2

H2O

Mn2+ NH4+ Fe2+ HS- CH4 H2 [CH2O]

+CO2

Respiration

O2-mediated

Mn -mediated

Fe-mediated

S-mediated

N-mediated

N2-fixation

The rise in oxygen

• The last big biological innovation on Earth

• Led to the rise of metazoans – and the success of aerobic eukaryotes.

• Altered Earth’s chemistry forever

Holding Oxygen concentrations in check

• Feedbacks with N cycle

• C cycle (photorespiration)

• And (later) oxidation of organic matter (lignins)