Selektive Neutralitt und Effizienz der Evolution Was wir aus - - PowerPoint PPT Presentation

Selektive Neutralität und Effizienz der Evolution

Was wir aus Evolutionsexperimenten lernen können Peter Schuster Institut für Theoretische Chemie und Molekulare Strukturbiologie der Universität Wien Seminar des Naturhistorischen Museums Wien, 28.04.2004

Web-Page for further information: http://www.tbi.univie.ac.at/~pks

200 400 600 800 1000 0.2 0.4 0.6 0.8 1 Zeit [Generationen] A n t e i l a n v

• r

t e i l h a f t e r V a r i a n t e s = 0.1 s = 0.01 s = 0.02 s = (f - f ) / f

2 1 1

Selektion vorteilhafter Varianten in einer Population von N = 10 000 Individuen

Massif Central Mount Fuji

Beispiele glatter Landschaften

Dolomiten

Beispiele zerklüfteter Landschaften

Bryce Canyon

Sequenzraum M i t t l e r e F i t n e ß

Start der Optimierung Ende

Optimierung auf einer Fitneßlandschaft ohne selektive Neutralität

Sequenzraum M i t t l e r e F i t n e ß

Start der Optimierung Start der Optimierung Start der Optimierung Ende Ende Ende

Optimierung auf einer Fitneßlandschaft ohne selektive Neutralität

Sequenzraum Mittlere Fitneß

Start der Optimierung Ende Zufallsdrift Adaptive Perioden

Evolutionäre Optimierung auf einer Landschaft mit neutralen Zonen

Grand Canyon

Beispiel einer Landschaft mit neutralen Graten und Plateaus

Neutrale Grate und Plateaus

„...Variations neither useful not injurious would not be affected by natural selection, and would be left either a fluctuating element, as perhaps we see in certain polymorphic species, or would ultimately become fixed,

• wing to the nature of the organism and the nature of

the conditions. ...“

Charles Darwin, Origin of species (1859)

The molecular clock of evolution

Motoo Kimura’s population genetics of neutral evolution. Evolutionary rate at the molecular level. Nature 217: 624-626, 1955. The Neutral Theory of Molecular Evolution. Canbridge University Press. Cambridge, UK, 1983.

Molecular evolution through comparison

• f sequences from different organisms

Five kingdoms.

• L. Margulis, K.V. Schwartz, W.H.Freeman & Co., 1982

Evolution at the molecular level.

R.K. Selander, A.G. Clark, T.S. Whittam, eds. Sinauer Associates, 1991.

Generation time 10 000 generations 106 generations 107 generations RNA molecules 10 sec 1 min 27.8 h = 1.16 d 6.94 d 115.7 d 1.90 a 3.17 a 19.01 a Bacteria 20 min 10 h 138.9 d 11.40 a 38.03 a 1 140 a 380 a 11 408 a Higher multicelluar

• rganisms

10 d 20 a 274 a 20 000 a 27 380 a 2 × 107 a 273 800 a 2 × 108 a

Time scales of evolutionary change

Bacterial Evolution

• S. F. Elena, V. S. Cooper, R. E. Lenski. Punctuated evolution caused by selection of

rare beneficial mutants. Science 272 (1996), 1802-1804

• D. Papadopoulos, D. Schneider, J. Meier-Eiss, W. Arber, R. E. Lenski, M. Blot.

Genomic evolution during a 10,000-generation experiment with bacteria. Proc.Natl.Acad.Sci.USA 96 (1999), 3807-3812

24 h 24 h

Serial transfer of Escherichia coli cultures in Petri dishes

1 day 6.67 generations 1 month 200 generations

• 1 year 2400 generations
• lawn of E.coli

nutrient agar

1 year

Epochal evolution of bacteria in serial transfer experiments under constant conditions

• S. F. Elena, V. S. Cooper, R. E. Lenski. Punctuated evolution caused by selection of rare beneficial mutants.

Science 272 (1996), 1802-1804

2000 4000 6000 8000 Time 5 10 15 20 25 Hamming distance to ancestor Generations

Variation of genotypes in a bacterial serial transfer experiment

• D. Papadopoulos, D. Schneider, J. Meier-Eiss, W. Arber, R. E. Lenski, M. Blot. Genomic evolution during a

10,000-generation experiment with bacteria. Proc.Natl.Acad.Sci.USA 96 (1999), 3807-3812

Evolution of RNA molecules based on Qβ phage

D.R.Mills, R,L,Peterson, S.Spiegelman, An extracellular Darwinian experiment with a self-duplicating nucleic acid molecule. Proc.Natl.Acad.Sci.USA 58 (1967), 217-224 S.Spiegelman, An approach to the experimental analysis of precellular evolution. Quart.Rev.Biophys. 4 (1971), 213-253 C.K.Biebricher, Darwinian selection of self-replicating RNA molecules. Evolutionary Biology 16 (1983), 1-52 C.K.Biebricher, W.C. Gardiner, Molecular evolution of RNA in vitro. Biophysical Chemistry 66 (1997), 179-192 G.Strunk, T. Ederhof, Machines for automated evolution experiments in vitro based on the serial transfer concept. Biophysical Chemistry 66 (1997), 193-202

RNA sample Stock solution: Q RNA-replicase, ATP, CTP, GTP and UTP, buffer

• Time

1 2 3 4 5 6 69 70 The serial transfer technique applied to RNA evolution in vitro

Reproduction of the original figure of the serial transfer experiment with Q RNA β D.R.Mills, R,L,Peterson, S.Spiegelman, . Proc.Natl.Acad.Sci.USA (1967), 217-224 An extracellular Darwinian experiment with a self-duplicating nucleic acid molecule 58

Decrease in mean fitness due to quasispecies formation

The increase in RNA production rate during a serial transfer experiment

Evolutionary design of RNA molecules

D.B.Bartel, J.W.Szostak, In vitro selection of RNA molecules that bind specific ligands. Nature 346 (1990), 818-822 C.Tuerk, L.Gold, SELEX - Systematic evolution of ligands by exponential enrichment: RNA ligands to bacteriophage T4 DNA polymerase. Science 249 (1990), 505-510 D.P.Bartel, J.W.Szostak, Isolation of new ribozymes from a large pool of random sequences. Science 261 (1993), 1411-1418 R.D.Jenison, S.C.Gill, A.Pardi, B.Poliski, High-resolution molecular discrimination by RNA. Science 263 (1994), 1425-1429

• Y. Wang, R.R.Rando, Specific binding of aminoglycoside antibiotics to RNA. Chemistry &

Biology 2 (1995), 281-290 Jiang, A. K. Suri, R. Fiala, D. J. Patel, Saccharide-RNA recognition in an aminoglycoside antibiotic-RNA aptamer complex. Chemistry & Biology 4 (1997), 35-50

No new principle will declare itself from below a heap of facts.

Sir Peter Medawar, 1985

G G G C C C C C C G G G C C C G G G C C C G G G G G G C C C

Plus Strand Plus Strand Plus Strand Minus Strand Minus Strand Minus Strand

3' 3' 3' 5' 5' 5' 5' 5' 5' 3' 3' 3'

+

Replication of DNA is a higly complex copying mechanism involving more than ten different protein

• molecules. Complementarity is determined by

Watson-Crick base pairs: G C and A=T

James Watson and Francis Crick, 1953

dx / dt = x - x x

i i i j j

; Σ = 1 ; i,j f f

i j

Φ Φ fi Φ = ( = Σ x

• i

)

j j

x =1,2,...,n [I ] = x 0 ;

i i

i =1,2,...,n ; Ii I1 I2 I1 I2 I1 I2 I i I n I i I n I n

+ + + + + +

(A) + (A) + (A) + (A) + (A) + (A) + fn fi f1 f2 I m I m I m

+

(A) + (A) + fm fm fj = max { ; j=1,2,...,n} xm(t) 1 for t

• [A] = a = constant

Reproduction of organisms or replication of molecules as the basis of selection

G G G C C C G C C G C C C G C C C G C G G G G C

Plus Strand Plus Strand Minus Strand Plus Strand 3' 3' 3' 3' 5' 3' 5' 5' 5'

Point Mutation Insertion Deletion

GAA AA UCCCG GAAUCC A CGA GAA AA UCCCGUCCCG GAAUCCA

The origins of changes in RNA sequences are replication errors called mutations.

Theory of molecular evolution

M.Eigen, Self-organization of matter and the evolution of biological macromolecules. Naturwissenschaften 58 (1971), 465-526 C.J. Thompson, J.L. McBride, On Eigen's theory of the self-organization of matter and the evolution

• f biological macromolecules. Math. Biosci. 21 (1974), 127-142

B.L. Jones, R.H. Enns, S.S. Rangnekar, On the theory of selection of coupled macromolecular

• systems. Bull.Math.Biol. 38 (1976), 15-28

M.Eigen, P.Schuster, The hypercycle. A principle of natural self-organization. Part A: Emergence of the hypercycle. Naturwissenschaften 58 (1977), 465-526 M.Eigen, P.Schuster, The hypercycle. A principle of natural self-organization. Part B: The abstract

• hypercycle. Naturwissenschaften 65 (1978), 7-41

M.Eigen, P.Schuster, The hypercycle. A principle of natural self-organization. Part C: The realistic

• hypercycle. Naturwissenschaften 65 (1978), 341-369
• J. Swetina, P. Schuster, Self-replication with errors - A model for polynucleotide replication.

Biophys.Chem. 16 (1982), 329-345 J.S. McCaskill, A localization threshold for macromolecular quasispecies from continuously distributed replication rates. J.Chem.Phys. 80 (1984), 5194-5202 M.Eigen, J.McCaskill, P.Schuster, The molecular quasispecies. Adv.Chem.Phys. 75 (1989), 149-263

• C. Reidys, C.Forst, P.Schuster, Replication and mutation on neutral networks. Bull.Math.Biol. 63

(2001), 57-94

Chemical kinetics of molecular evolution

• M. Eigen, P. Schuster, `The Hypercycle´,

Springer-Verlag, Berlin 1979

Ij In I2 Ii I1 I j I j I j I j I j I j

+ + + + +

(A) + fj Qj1 fj Qj2 fj Qji fj Qjj fj Qjn Q (1- )

ij

• d(i,j)

d(i,j)

=

l

p p

p .......... Error rate per digit d(i,j) .... Hamming distance between Ii and Ij ........... Chain length of the polynucleotide l

dx / dt = x - x x

i j j i j j

Σ

; Σ = 1 ; f f x

j j j i

Φ Φ = Σ Qji Qij

Σi

= 1 [A] = a = constant [Ii] = xi 0 ;

• i =1,2,...,n ;

Chemical kinetics of replication and mutation as parallel reactions

space Sequence C

• n

c e n t r a t i

• n

Master sequence Mutant cloud

The molecular quasispecies in sequence space

N1

N2

N3

N4

N A U G C

k =

, , ,

3' - end 5' - end Na Na Na Na

RNA

nd 3’-end

GCGGAU AUUCGC UUA AGUUGGGA G CUGAAGA AGGUC UUCGAUC A ACCA GCUC GAGC CCAGA UCUGG CUGUG CACAG 3'-end 5’-end

70 60 50 40 30 20 10

Definition of RNA structure

5'-e

Optimization of RNA molecules in silico

W.Fontana, P.Schuster, A computer model of evolutionary optimization. Biophysical Chemistry 26 (1987), 123-147 W.Fontana, W.Schnabl, P.Schuster, Physical aspects of evolutionary optimization and

• adaptation. Phys.Rev.A 40 (1989), 3301-3321

M.A.Huynen, W.Fontana, P.F.Stadler, Smoothness within ruggedness. The role of neutrality in adaptation. Proc.Natl.Acad.Sci.USA 93 (1996), 397-401 W.Fontana, P.Schuster, Continuity in evolution. On the nature of transitions. Science 280 (1998), 1451-1455 W.Fontana, P.Schuster, Shaping space. The possible and the attainable in RNA genotype- phenotype mapping. J.Theor.Biol. 194 (1998), 491-515 B.M.R. Stadler, P.F. Stadler, G.P. Wagner, W. Fontana, The topology of the possible: Formal spaces underlying patterns of evolutionary change. J.Theor.Biol. 213 (2001), 241-274

Evolution in silico

• W. Fontana, P. Schuster,

Science 280 (1998), 1451-1455

Optimized element: RNA structure

Stock Solution Reaction Mixture

Replication rate constant: fk = / [+ dS

(k)]

• dS

(k) = dH(Sk,S

) Selection constraint: # RNA molecules is controlled by the flow N N t N ± ≈ ) ( The flowreactor as a device for studies of evolution in vitro and in silico

5'-End 3'-End

70 60 50 40 30 20 10

Randomly chosen initial structure Phenylalanyl-tRNA as target structure

s p a c e Sequence Concentration

Master sequence Mutant cloud “Off-the-cloud” mutations

The molecular quasispecies in sequence space

f0 f f1 f2 f3 f4 f6 f5 f7

Replication rate constant: fk = / [+ dS

(k)]

• dS

(k) = dH(Sk,S

)

Evaluation of RNA secondary structures yields replication rate constants

In silico optimization in the flow reactor: Trajectory (biologists‘ view) Time (arbitrary units) A v e r a g e d i s t a n c e f r

• m

i n i t i a l s t r u c t u r e 5

• d
• S

500 750 1000 1250 250 50 40 30 20 10

Evolutionary trajectory

10 08 12 14 Time (arbitrary units) Average structure distance to target dS

• 500

250 20 10

Uninterrupted presence Evolutionary trajectory Number of relay step

28 neutral point mutations during a long quasi-stationary epoch Transition inducing point mutations Neutral point mutations

Neutral genotype evolution during phenotypic stasis

Variation in genotype space during optimization of phenotypes

Mean Hamming distance within the population and drift velocity of the population center in sequence space.

Spread of population in sequence space during a quasistationary epoch: t = 150

Spread of population in sequence space during a quasistationary epoch: t = 170

Spread of population in sequence space during a quasistationary epoch: t = 200

Spread of population in sequence space during a quasistationary epoch: t = 350

Spread of population in sequence space during a quasistationary epoch: t = 500

Spread of population in sequence space during a quasistationary epoch: t = 650

Spread of population in sequence space during a quasistationary epoch: t = 820

Spread of population in sequence space during a quasistationary epoch: t = 825

Spread of population in sequence space during a quasistationary epoch: t = 830

Spread of population in sequence space during a quasistationary epoch: t = 835

Spread of population in sequence space during a quasistationary epoch: t = 840

Spread of population in sequence space during a quasistationary epoch: t = 845

Spread of population in sequence space during a quasistationary epoch: t = 850

Spread of population in sequence space during a quasistationary epoch: t = 855

AUGC GC Movies of optimization trajectories over the AUGC and the GC alphabet

Alphabet Runtime Transitions Main transitions

• No. of runs

AUGC 385.6 22.5 12.6 1017 GUC 448.9 30.5 16.5 611 GC 2188.3 40.0 20.6 107

Statistics of trajectories and relay series (mean values of log-normal distributions)

Theory of sequence – structure mappings

• P. Schuster, W.Fontana, P.F.Stadler, I.L.Hofacker, From sequences to shapes and back:

A case study in RNA secondary structures. Proc.Roy.Soc.London B 255 (1994), 279-284 W.Grüner, R.Giegerich, D.Strothmann, C.Reidys, I.L.Hofacker, P.Schuster, Analysis of RNA sequence structure maps by exhaustive enumeration. I. Neutral networks. Mh.Chem. 127 (1996), 355-374 W.Grüner, R.Giegerich, D.Strothmann, C.Reidys, I.L.Hofacker, P.Schuster, Analysis of RNA sequence structure maps by exhaustive enumeration. II. Structure of neutral networks and shape space covering. Mh.Chem. 127 (1996), 375-389 C.M.Reidys, P.F.Stadler, P.Schuster, Generic properties of combinatory maps. Bull.Math.Biol. 59 (1997), 339-397 I.L.Hofacker, P. Schuster, P.F.Stadler, Combinatorics of RNA secondary structures. Discr.Appl.Math. 89 (1998), 177-207 C.M.Reidys, P.F.Stadler, Combinatory landscapes. SIAM Review 44 (2002), 3-54

Reference for postulation and in silico verification of neutral networks

A connected neutral network

Giant Component

A multi-component neutral network

RNA 9:1456-1463, 2003

Evidence for neutral networks and shape space covering

Evidence for neutral networks and intersection of apatamer functions

Reference for the definition of the intersection and the proof of the intersection theorem

Gk Neutral Network

Structure S

k

Gk C k

Compatible Set Ck

The compatible set Ck of a structure Sk consists of all sequences which form Sk as its minimum free energy structure (the neutral network Gk) or one of its suboptimal structures.

Structure S Structure S

1

The intersection of two compatible sets is always non empty: C0 C1

A ribozyme switch

E.A.Schultes, D.B.Bartel, Science 289 (2000), 448-452

Two ribozymes of chain lengths n = 88 nucleotides: An artificial ligase (A) and a natural cleavage ribozyme of hepatitis-

• virus (B)

The sequence at the intersection: An RNA molecules which is 88 nucleotides long and can form both structures

Two neutral walks through sequence space with conservation of structure and catalytic activity

Wolfgang Wieser. Die Erfindung der Individualität oder die zwei Gesichter der Evolution. Spektrum Akademischer Verlag, Heidelberg 1998. A.C.Wilson. The Molecular Basis of Evolution. Scientific American, Oct.1985, 164-173.

1968 2004

Evolution (Cartoon 1980)

Acknowledgement of support

Fonds zur Förderung der wissenschaftlichen Forschung (FWF) Projects No. 09942, 10578, 11065, 13093 13887, and 14898 Jubiläumsfonds der Österreichischen Nationalbank Project No. Nat-7813 European Commission: Project No. EU-980189 Siemens AG, Austria The Santa Fe Institute and the Universität Wien The software for producing RNA movies was developed by Robert Giegerich and coworkers at the Universität Bielefeld

Universität Wien

Coworkers

Universität Wien

Walter Fontana, Santa Fe Institute, NM Christian Reidys, Christian Forst, Los Alamos National Laboratory, NM Peter Stadler, Bärbel Stadler, Universität Leipzig, GE Ivo L.Hofacker, Christoph Flamm, Universität Wien, AT Andreas Wernitznig, Michael Kospach, Universität Wien, AT Ulrike Langhammer, Ulrike Mückstein, Stefanie Widder Jan Cupal, Kurt Grünberger, Andreas Svrček-Seiler, Stefan Wuchty Ulrike Göbel, Institut für Molekulare Biotechnologie, Jena, GE Walter Grüner, Stefan Kopp, Jaqueline Weber

Web-Page for further information: http://www.tbi.univie.ac.at/~pks