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 f...

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Bibliographic Details
Published in:Scientific reports 2017-02, Vol.7 (1), p.41662, Article 41662
Main Authors: Vernhes, Emeline, Renouard, Madalena, Gilquin, Bernard, Cuniasse, Philippe, Durand, Dominique, England, Patrick, Hoos, Sylviane, Huet, Alexis, Conway, James F., Glukhov, Anatoly, Ksenzenko, Vladimir, Jacquet, Eric, Nhiri, Naïma, Zinn-Justin, Sophie, Boulanger, Pascale
Format: Article
Language:English
Subjects:
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Affinity
Capsid protein
Capsids
Genomes
Harsh environments
Hexamers
Humanities and Social Sciences
Immunoglobulins
Life Sciences
multidisciplinary
Phages
Proteins
Science
Shells
Structure-function relationships
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Summary: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.
ISSN:2045-2322
2045-2322
DOI:10.1038/srep41662