Article (Scientific journals)
De novo backbone and sequence design of an idealized alpha/beta-barrel protein: Evidence of stable tertiary structure
Offredi, Fabrice; Dubail, Fabien; Kischel, Philippe et al.
2003In Journal of Molecular Biology, 325 (1), p. 163-174
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De novo Backbone and Sequence Design of an Idealized alpha-beta-barrel Protein-Evidence of Stable Tertiary Structure (Offredi 2003).pdf
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Keywords :
protein design; backbone parameterization; side-chain modeling; fluorescence; circular dichroism
Abstract :
[en] We have designed, synthesized, and characterized a 216 amino acid residue sequence encoding a putative idealized alpha/beta-barrel protein. The design was elaborated in two steps. First, the idealized backbone was defined with geometric parameters representing our target fold: a central eight parallel-stranded beta-sheet surrounded by eight parallel alpha-helices, connected together with short structural turns on both sides of the barrel. An automated sequence selection algorithm, based on the dead-end elimination theorem, was used to find the optimal amino acid sequence fitting the target structure. A synthetic gene coding for the designed sequence was constructed and the recombinant artificial protein was expressed in bacteria, purified and characterized. Far-UV CD spectra with prominent bands at 222nm and 208nm revealed the presence of alpha-helix secondary structures (50%) in fairly good agreement with the model. A pronounced absorption band in the near-UV CD region, arising from immobilized aromatic side-chains, showed that the artificial protein is folded in solution. Chemical unfolding monitored by tryptophan fluorescence revealed a conformational stability (DeltaG(H2O)) of 35kJ/mol. Thermal unfolding monitored by near-UV CD revealed a cooperative transition with an apparent T(m) of 65 degrees C. Moreover, the artificial protein did not exhibit any affinity for the hydrophobic fluorescent probe 1-anilinonaphthalene-8-sulfonic acid (ANS), providing additional evidence that the artificial barrel is not in the molten globule state, contrary to previously designed artificial alpha/beta-barrels. Finally, 1H NMR spectra of the folded and unfolded proteins provided evidence for specific interactions in the folded protein. Taken together, the results indicate that the de novo designed alpha/beta-barrel protein adopts a stable three-dimensional structure in solution. These encouraging results show that de novo design of an idealized protein structure of more than 200 amino acid residues is now possible, from construction of a particular backbone conformation to determination of an amino acid sequence with an automated sequence selection algorithm.
Disciplines :
Biochemistry, biophysics & molecular biology
Author, co-author :
Offredi, Fabrice;  Université de Liège - ULiège > Département des Sciences Biomédicales et Précliniques > Biologie Moléculaire et Génie Génétique
Dubail, Fabien;  Université de Liège - ULiège > Département des sciences biomédicales et précliniques > Biologie Moléculaire et Génie Génétique
Kischel, Philippe ;  Université de Liège - ULiège > Département des sciences biomédicales et précliniques > Biologie Moléculaire et Génie Génétique
Sarinski, K.
Stern, A. S.
Van de Weerdt, Cécile ;  Université de Liège - ULiège > Département des sciences de la vie > Biologie Moléculaire et Génie Génétique
Hoch, J. C.
Prosperi, Christelle ;  Université de Liège - ULiège > Département de physique > Département de physique
François, Jean-Marie ;  Université de Liège - ULiège > Département des sciences biomédicales et précliniques > Biologie Moléculaire et Génie Génétique
Mayo, S. L.
Martial, Joseph ;  Université de Liège - ULiège > Département des sciences de la vie > GIGA-R : Biologie et génétique moléculaire
Language :
English
Title :
De novo backbone and sequence design of an idealized alpha/beta-barrel protein: Evidence of stable tertiary structure
Publication date :
03 January 2003
Journal title :
Journal of Molecular Biology
ISSN :
0022-2836
eISSN :
1089-8638
Publisher :
Academic Press Ltd Elsevier Science Ltd, London, United Kingdom
Volume :
325
Issue :
1
Pages :
163-174
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 04 May 2009

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