High affinity anchoring of the decoration protein pb10 onto the bacteriophage T5 capsid.
Bacteriophage capsids constitute icosahedral shells of exceptional stability that protect the viral genome. Many capsids display on their surface decoration proteins whose structure and function remain largely unknown. The decoration protein pb10 of phage T5 binds at the centre of the 120 hexamers formed by the major capsid protein. Here we determined the 3D structure of pb10 and investigated its capsid-binding properties using NMR, SAXS, cryoEM and SPR. Pb10 consists of an α-helical capsid-binding domain and an Ig-like domain exposed to the solvent. It binds to the T5 capsid with a remarkably high affinity and its binding kinetics is characterized by a very slow dissociation rate. We propose that the conformational exchange events observed in the capsid-binding domain enable rearrangements upon binding that contribute to the quasi-irreversibility of the pb10-capsid interaction. Moreover we show that pb10 binding is a highly cooperative process, which favours immediate rebinding of newly dissociated pb10 to the 120 hexamers of the capsid protein. In extreme conditions, pb10 protects the phage from releasing its genome. We conclude that pb10 may function to reinforce the capsid thus favouring phage survival in harsh environments.
Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette cedex, France.
Emeline
E
Vernhes
Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette cedex, France.
Madalena
M
Renouard
Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette cedex, France.
Bernard
B
Gilquin
Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette cedex, France.
Philippe
P
Cuniasse
Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette cedex, France.
Dominique
D
Durand
Institut Pasteur, Biophysique Moléculaire, Citech, UMR 3528, Paris, France.
Patrick
P
England
Institut Pasteur, Biophysique Moléculaire, Citech, UMR 3528, Paris, France.
Sylviane
S
Hoos
Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
Alexis
A
Huet
Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
James F
JF
Conway
Institute of Protein Research, Russian Academy of Sciences, Pushchino, Russia.
Anatoly
A
Glukhov
Institute of Protein Research, Russian Academy of Sciences, Pushchino, Russia.
Vladimir
V
Ksenzenko
Institut de Chimie des Substances Naturelles, Univ Paris-Sud, Université Paris-Saclay, CNRS UPR 2301, Gif-sur-Yvette, France.
Eric
E
Jacquet
Institut de Chimie des Substances Naturelles, Univ Paris-Sud, Université Paris-Saclay, CNRS UPR 2301, Gif-sur-Yvette, France.
Naïma
N
Nhiri
Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette cedex, France.
Sophie
S
Zinn-Justin
Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette cedex, France.
Pascale
P
Boulanger