a ‘m olecular d eal ’ between lipophilic peptides and hydrophilic nucleic acids helped to...

A ‘MOLECULAR DEAL’ between lipophilic peptides and hydrophilic nucleic acids helped to overcome the major

selection obstacle of each class of compounds : Too low mobility and irreversible precipitation of peptides.

Too high mobility and infinite dilution of nucleic acids.

Basic Questions about the Origin of Life

ON THE GENETIC CODE

A proposition by Peter Strazewski, Lyon

Angewandte Chemie

International Edition in English,

1972, 11, 798-8301972

Angewandte Chemie

International Edition in English,

1981, 20, 500-520

Angewandte Chemie

International Edition in English,

1981, 20, 500-520

Journal of

Molecular Evolution,

1989, 29, 465-474

A) 3'-aminoacyl-RNA

B) Uncoded peptidyl transfer

C) mRNA-encoded peptidyl transfer (PT)

D) ribosome-catalysed and mRNA-encoded PT

Eörs Szathmáry in:

«Evolution: from

Cosmogenesis to Biogenesis»

(B. Lukacs et al. eds.)

KFKI 1990, 50/C, 77-83

Origin of genetically encoded protein synthesis : A model based on selection for RNA peptidation

Origin of Life and

Evolution of the Biosphere,

1991, 21, 165-176

A) 3'-aminoacyl-AMP + 3'-peptidyl-RNA

B) Uncoded peptidyl transfer

C) mRNA-encoded peptidyl transfer

Jeffrey Tze-Fei Wong

Early Middle Late

A1-AMP A3-tRNA3 A3-tRNA3

+ A2-A3-tRNA3 + A1-A2-tRNA2 + A1-A2-tRNA2

A1-A2-A3-tRNA3

===

===

TemplateRNA

III

On the origin of protein synthesis : A speculative model based on hairpin RNA structures

Journal of

Theoretical Biology,

1994, 171, 303-8

A) Uncoded peptidyl transfer through (bulged) double-strand formation between

3'-aminoacyl-RNA hairpin (+) RNA hairpin (+) 5'-aminoacyl-RNA hairpin => 5'-dipeptidyl-RNA hairpin (-)

5'-aminoacyl-RNA hairpin (-) 5'-dipeptidyl-RNA hairpin (-)

B) Stabilisation of cruciforms between the above hairpins through mRNA

C) mRNA-encoded peptidyl transfer between 3'-aminoacyl and 3'-peptidyl-tRNAs

D) rRNA-catalysed peptidyl transfer

Massimo Di Giulio

1994

1994 (reproduced from 1987)

Experimentally taken care of by:

John D. Sutherland, Manchester, UK

Prebiotic Aminoacylation of Nucleotides

Chemistry & Biodiversity 2004, 1, 203-246

More contributions to the origin of tRNA as a basis for the appearance of the genetic code and translation (and replication) :

Manfred Eigen, Peter Schuster, Ruthild Winkler 1972, 1981, 1989Jeffrey Tze-Fei Wong 1975-2006, ...Massimio Di Giulio 1989-2006, ...Toby Gibson & Angus Lamond 1990Tobias Dick & Wolfgang Schamel 1995Nancy Maizels & Alun Weiner 1987-1999

...

Importance of compartmentalisation and the matrix effect :

William Hargreaves, Sean Mulvihill,David Deamer et al. 1977- ...

Pier Luigi Luisi, Peter Walde, Evelyne Blöchliger, Markus Blocher et al. 1998-2004

Jack Szostak, Martin Hanczyc 2001- ...

MAJOR PLAYERS

NUCLEICACIDS

replicateprimary

sequence

PROTEINS

recognise

LIPIDS

replicateshape

SUGARS

recognise

HYDROPHILES AMPHIPHILES

A-RNA hairpin-3'-oligopeptidehydrophilic lipophilic

shallowgroove

deepgroove

shallowgroove

-helixA-RNA

5’-RNA-3’-(Ala)21

UUCGloop

ACCAstack

ACCAstack

UUCGloop

deepgroove

-helix

helixdipole

shallowgroove

shallowgroove

deepgroove

A-RNA hairpin-3'-oligopeptidehydrophilic lipophilic

-strandA-RNA

5’-RNA-3’-(Ala)21UUCGloop

ACCAstack

MOLECULAR DEAL

N.A. to P.P.: « I'll help you to stay in solution,

if you help me not to get washed away »

P.P. to N.A.: « I'll help you to stick around,

if you help me to hold sufficient distance to my buddies »

love you both