Magnetite biomineralization in M. gryphiswaldense · 2009-02-05 · 26 June 2006 Damien Faivre – Workshop on Complex Materials Genomic Island whole genome shotgun 482 kb WGS 50K

26 June 2006 Damien Faivre – Workshop on Complex Materials

Magnetite biomineralization in M. gryphiswaldense

Damien Faivre

June 26th, 2006


Biomineralization

→ formation of minerals by living organisms (bacteria, higher organisms…)

armature

attack defense


Iron biomineralization

Iron oxide Organism Position Function

MagnetiteFe3O4

BacteriaChitons

FishBirds

CellsTeethHeadHead

OrientationHardness

OrientationOrientation

Goethiteα-FeOOH

Patels Teeth Hardness

Lepidocrociteγ-FeOOH

SpongesChitons

SpiculeTeeth

AnchoringHardness

Ferrihydrite5Fe2O3.9H2O

Animals –plants

Chitons

Ferritine

Teeth

Stocking

Precursor


Iron biomineralization: example

Chiton Radulae:

• Magnetite (Fe3O4): on the surface

• Lepidocrocite (γ-FeOOH): fine underlying layer

• Dahllite ([Ca5(PO4-CO3)3(OH)]): interior


Magnetotactic bacteria

microaerophilic α-Proteobacterium synthesizing magnetosomes


Magnetotaxis

NS


Magnetic orientation relies on

magnetosomes

S

N

ANOXIC

OXIC

MICROOXIC


Magnetosomes

• Species-specific morphology

• Membrane-enclosed

• Biocompatible

Scale bar 100 nm*Schüler, 1999


Magnetosomes

• Nano-crystals: 30-120 nm• Narrow size distribution

0.00

5.00

10.00

15.00

20.00

25.00

30.00

0 10 20 30 40 50 60

size (nm)

frequ

ency

(%)

*Faivre et al., 2006 *Posfai et al., 2006


Functionalized magnetosomes

Applications in Biotechnology:

In vitroImmunoassays Separation of biomolecules

In vivoMagnetic drug targetingHyperthermiaMagnetic resonance imaging


Fluorescence of isolated particles


Magnetic properties• Size within single

magnetic-domain– Below ~ 25 nm

superparamagnetic – Above 100 nm

multidomain• High coercivity

– 6500 A × m-1

(magnetosomes) in comparison to 20 A×m-1 (Schering) (Eberbeck, 2004) *Simpson et al., 2005


Why iron biomineralization?

• biotechnological applications

• proxies for environmental change

• model for nanomolecular interactions between living (bacteria) and non-living (minerals) systems

• model for biomineralization in higher organisms magnetoreception


Genomic Islandwhole genome shotgun 482 kb WGS

50K 100K 150K 200K 250K 300K 350K 400K 450K

130 kb region

mms/mam genes transposase genes hypothetical genes genes with other attributed functions

130 kb core region

tRNA genes

220K 230K 240K 250K 260K 270K 280K 290K 300K 310K 320K 330K 340K 350K

The mam-genes encoding magnetosome membrane proteins are arranged in genomic island (Ullrich et al., 2005)


The chain under genetic control*

*Scheffel et al., Nature, 2006


The chain under genetic control*

*Scheffel et al., Nature, 2006 and Komeili et al., Science, 2006


Biochemistry of magnetite formation

*Bazylinski and Frankel., Nature Rev., 2004


Proposed reaction pathway*

*Frankel et al., 1983

1. Fe(III) cell exterior

→ Fe(II) cell interior

2. Low density Fe(III) oxyde

3. Ferrihydrite

4. Magnetite

But:

1. No controlled conditions

2. Lack dynamic of process

3. Need association with some other techniques


Controlled growth in fermentor

Control of:

1.Temperature

2.pH

3.PO2


Induction experiments

0 min 55 min 100 min 220 min 340 min

Allow to follow the dynamic of the process


Minimal medium

How to study chain formation in growing cells?

0

50

100

150

200

250

0 1 2 3 4 5 6

time (h)

OD

565 (

*100

0)

0.00

0.50

1.00

1.50

2.00

2.50

3.00

Cm

ag (a

. u.)

1. Iron uptake just for magnetite formation, not for growth

2. Parameters such as # crystals / cell not disturbed by cell division


Evolution of mineralogical properties

time after induction 0h55 1h40 2h10 2h40 3h40 5h40

Magnetism 0.01 0.18 0.53 1.05 1.62 2.40

crystals per cell 16 17.8 17 23.6 20.3 28.8

Average size of crystals

(nm)19 19.4 20.3 22.7 26.3 33.1

Inter-crystal distance

(nm)127 75 56 41 29 19


Implications

2. Magnetic pool

1. “classical” iron storage


Magnetite biomineralization

• Magnetization really due to pure Magnetite ? Magnetite / Maghemite mixture?

• Is there any intermediate?

• What is the nature of the other pool of iron?

→ Mössbauer spectroscopy


Magnetite or Maghemite

Magnetite : Maghemite :• Magnetite: – 2 Sextets (δ = 0.26 & δ = 0.67 mms-1)– a ratio of 1:2 for the Sextet above the Verwey

transistion (T > 119 K), 1:1 below

• Maghemite: – 1 Sextet (δ = 0.32 mms-1) at room temperature– At 4.2K the spectrum splits into two Sextets

(δ = 0.40 & δ = 0.48 mms-1)


-10 -5 0 5 100,75

0,80

0,85

0,90

0,95

1,00

Spectra Simulation A B Ferritin 4Fe4S FEII

Rel

ativ

e Tr

ansm

issi

on

velocity (mm/s)

Identification of the iron pools


Isolated magnetosomes

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 100,80

0,82

0,84

0,86

0,88

0,90

0,92

0,94

0,96

0,98

1,00

spectrum simulation A B

Rel

ativ

e Tr

ansm

issi

on

velocity (mm/s)


Dynamic of magnetite formation

-10 -8 -6 -4 -2 0 2 4 6 8 10

0,8

0,9

1,0

1,1

Rel

ativ

e Tr

ansm

issi

on

velocity (mm/s)

20h30m

20m40m60m95m125m155m215m


Iron uptake in non-magnetic mutantwhole genome shotgun 482 kb WGS

50K 100K 150K 200K 250K 300K 350K 400K 450K

130 kb region

mms/mam genes transposase genes hypothetical genes genes with other attributed functions

130 kb core region

tRNA genes

220K 230K 240K 250K 260K 270K 280K 290K 300K 310K 320K 330K 340K 350K

MSR-1B lacks the complete genomic island


Identification of the iron pools

-5 -4 -3 -2 -1 0 1 2 3 4 50,965

0,970

0,975

0,980

0,985

0,990

0,995

1,000

spectrum simulation 4Fe4S unknown Ferritin

Rel

ativ

e Tr

ansm

issi

on

velocity (mm/s)

The Ferritin-like component split into a magneticsextett at low temperature.


Implications

• Different pools of iron:

1. Ferrous, ferritin, [Fe-S] and magnetite in WT, and no magnetite but unknown compounds in mutant

2. No ferric, no ferrihydrite

• Certainly no intermediate for magnetite biomineralization

• No trace of maghemite


1. Fe(III) cell exterior

or Fe(II) cell exterior

2. Fe(II) cell interior

+ ferritin

and [Fe-S]

3. Magnetite


But:Fe1. Ferritin

+ [Fe-S]

2. Magnetite

OR?

Fe 1. Ferritin + [Fe-S] 2. Magnetite


AcknowledgementsThe Magneto-Lab

E. SimpsonDr. R. Dunin Borkowski

Dr. N. Menguy

L. BoettgerProf. B. Matzanke


Thank you for your attention

Documents

Magnetite biomineralization in M. gryphiswaldense · 2009-02-05 · 26 June 2006 Damien Faivre – Workshop on Complex Materials Genomic Island whole genome shotgun 482 kb WGS 50K