Tài liệu Báo cáo khoa học: How disorder influences order and vice versa – mutual effects in fusion

How disorder influences order and vice versa – mutual

effects in fusion proteins containing an intrinsically

disordered and a globular protein

Ilaria Sambi1

, Pietro Gatti-Lafranconi1

*, Sonia Longhi2 and Marina Lotti1

1 Dipartimento di Biotecnologie e Bioscienze, Universita` di Milano-Bicocca, Italy

2 Architecture et Fonction des Macromole´ cules Biologiques, Universite´ Aix-Marseille I et II, France

Introduction

Until very recently, one of the pillars of protein science

has been the so-called structure–function paradigm,

which posits the formation of a unique 3D structure as

the prerequisite for biological function [1]. However,

during the last decade, numerous proteins have been

described that fail to adopt a stable tertiary structure

under physiological conditions and yet display biologi￾cal activity [2]. This condition, defined as intrinsic

disorder, has been found to be widespread in func￾tional proteins. Importantly, disordered regions are

often required for biological activity, indicating that

the lack of stable secondary and tertiary structure is a

Keywords

conformation; fusion proteins; intrinsically

disordered proteins; stability; viral proteins

Correspondence

M. Lotti, Dipartimento di Biotecnologie e

Bioscienze, Universita` di Milano-Bicocca,

Piazza della Scienza 2, 20126 Milano, Italy

Fax: +3902 6448 3569

Tel: +3902 6448 3527

E-mail: marina.lotti@unimib.it or

S. Longhi, Architecture et Fonction des

Macromolecules Biologiques (AFMB), UMR

6098 CNRS et Universite´ s d’Aix-Marseille I

et II, 163, Avenue de Luminy, Case 932,

13288 Marseille, Cedex 09, France

Fax: +33 (0) 4 91 26 67 20

Tel: +33 (0) 4 91 82 55 80

E-mail: sonia.longhi@afmb.univ-mrs.fr

*Present address

Biochemistry Department, University of

Cambridge, UK

(Received 30 June 2010, revised 10 August

2010, accepted 23 August 2010)

doi:10.1111/j.1742-4658.2010.07825.x

Intrinsically disordered proteins (IDPs) are functional proteins either fully

or partly lacking stable secondary and tertiary structure under physiologi￾cal conditions that are involved in important biological functions, such as

regulation and signalling in eukaryotes, prokaryotes and viruses. The func￾tion of many IDPs relies upon interactions with partner proteins, often

accompanied by conformational changes and disorder-to-order transitions

in the unstructured partner. To investigate how disordered and ordered

regions interact when fused to one to another within the same protein, we

covalently linked the green fluorescent protein to three different, well char￾acterized IDPs and analyzed the conformational properties of the fusion

proteins using various biochemical and biophysical approaches. We

observed that the overall structure, compactness and stability of the chime￾ric proteins all differ from what could have been anticipated from the

structural features of their isolated components and that they vary as a

function of the fused IDP.

Abbreviations

GFP, green fluorescent protein; IDP, intrinsically disordered protein.

4438 FEBS Journal 277 (2010) 4438–4451 ª 2010 The Authors Journal compilation ª 2010 FEBS