Crystal Structure of the Receptor-Binding Protein Head Domain from Lactococcus lactis Phage bIL170

ABSTRACT Lactococcus lactis, a gram-positive bacterium widely used by the dairy industry, is subject to lytic phage infections. In the first step of infection, phages recognize the host saccharidic receptor using their receptor binding protein (RBP). Here, we report the 2.30-Å-resolution crystal structure of the RBP head domain from phage bIL170. The structure of the head monomer is remarkably close to those of other lactococcal phages, p2 and TP901-1, despite any sequence identity with them. The knowledge of the three-dimensional structures of three RBPs gives a better insight into the module exchanges which have occurred among phages.

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The Atomic Structure of the Phage Tuc2009 Baseplate Tripod Suggests that Host Recognition Involves Two Different Carbohydrate Binding Modules

mBio ◽

10.1128/mbio.01781-15 ◽

2016 ◽

Vol 7 (1) ◽

Cited By ~ 32

Author(s):

Pierre Legrand ◽

Barry Collins ◽

Stéphanie Blangy ◽

James Murphy ◽

Silvia Spinelli ◽

...

Keyword(s):

Lactococcus Lactis ◽

Receptor Binding ◽

Binding Protein ◽

Structural Features ◽

Host Recognition ◽

Carbohydrate Binding ◽

Major Step ◽

Head Domain ◽

Carbohydrate Binding Modules ◽

Receptor Binding Protein

ABSTRACTThe Gram-positive bacteriumLactococcus lactis, used for the production of cheeses and other fermented dairy products, falls victim frequently to fortuitous infection by tailed phages. The accompanying risk of dairy fermentation failures in industrial facilities has prompted in-depth investigations of these phages. Lactococcal phage Tuc2009 possesses extensive genomic homology to phage TP901-1. However, striking differences in the baseplate-encoding genes stimulated our interest in solving the structure of this host’s adhesion device. We report here the X-ray structures of phage Tuc2009 receptor binding protein (RBP) and of a “tripod” assembly of three baseplate components, BppU, BppA, and BppL (the RBP). These structures made it possible to generate a realistic atomic model of the complete Tuc2009 baseplate that consists of an 84-protein complex: 18 BppU, 12 BppA, and 54 BppL proteins. The RBP head domain possesses a different fold than those of phages p2, TP901-1, and 1358, while the so-called “stem” and “neck” domains share structural features with their equivalents in phage TP901-1. The BppA module interacts strongly with the BppU N-terminal domain. Unlike other characterized lactococcal phages, Tuc2009 baseplate harbors two different carbohydrate recognition sites: one in the bona fide RBP head domain and the other in BppA. These findings represent a major step forward in deciphering the molecular mechanism by which Tuc2009 recognizes its saccharidic receptor(s) on its host.IMPORTANCEUnderstanding how siphophages infectLactococcus lactisis of commercial importance as they cause milk fermentation failures in the dairy industry. In addition, such knowledge is crucial in a general sense in order to understand how viruses recognize their host through protein-glycan interactions. We report here the lactococcal phage Tuc2009 receptor binding protein (RBP) structure as well as that of its baseplate. The RBP head domain has a different fold than those of phages p2, TP901-1, and 1358, while the so-called “stem” and “neck” share the fold characteristics also found in the equivalent baseplate proteins of phage TP901-1. The baseplate structure contains, in contrast to other characterized lactococcal phages, two different carbohydrate binding modules that may bind different motifs of the host’s surface polysaccharide.

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Crystal Structure of Thaumatin I, a Sweet Taste Receptor Binding Protein

Crystallography in Molecular Biology ◽

10.1007/978-1-4684-5272-3_36 ◽

1987 ◽

pp. 395-402

Author(s):

Abraham de Vos ◽

Sung-Hou Kim

Keyword(s):

Crystal Structure ◽

Receptor Binding ◽

Binding Protein ◽

Taste Receptor ◽

Sweet Taste ◽

Sweet Taste Receptor ◽

Receptor Binding Protein

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Molecular Insights on the Recognition of a Lactococcus lactis Cell Wall Pellicle by the Phage 1358 Receptor Binding Protein

Journal of Virology ◽

10.1128/jvi.00739-14 ◽

2014 ◽

Vol 88 (12) ◽

pp. 7005-7015 ◽

Cited By ~ 38

Author(s):

C. Farenc ◽

S. Spinelli ◽

E. Vinogradov ◽

D. Tremblay ◽

S. Blangy ◽

...

Keyword(s):

Cell Wall ◽

Lactococcus Lactis ◽

Receptor Binding ◽

Binding Protein ◽

Receptor Binding Protein

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Receptor-Binding Protein of Lactococcus lactis Phages: Identification and Characterization of the Saccharide Receptor-Binding Site

Journal of Bacteriology ◽

10.1128/jb.188.7.2400-2410.2006 ◽

2006 ◽

Vol 188 (7) ◽

pp. 2400-2410 ◽

Cited By ~ 82

Author(s):

Denise M. Tremblay ◽

Mariella Tegoni ◽

Silvia Spinelli ◽

Valérie Campanacci ◽

Stéphanie Blangy ◽

...

Keyword(s):

Binding Site ◽

Lactococcus Lactis ◽

Receptor Binding ◽

Binding Protein ◽

Receptor Binding Site ◽

Glycerol Molecule ◽

Vh Domain ◽

Interaction Surface ◽

Receptor Binding Protein

ABSTRACT Phage p2, a member of the lactococcal 936 phage species, infects Lactococcus lactis strains by binding initially to specific carbohydrate receptors using its receptor-binding protein (RBP). The structures of p2 RBP, a homotrimeric protein composed of three domains, and of its complex with a neutralizing llama VH domain (VHH5) have been determined (S. Spinelli, A. Desmyter, C. T. Verrips, H. J. de Haard, S. Moineau, and C. Cambillau, Nat. Struct. Mol. Biol. 13:85-89, 2006). Here, we show that VHH5 was able to neutralize 12 of 50 lactococcal phages belonging to the 936 species. Moreover, escape phage mutants no longer neutralized by VHH5 were isolated from 11 of these phages. All of the mutations (but one) cluster in the RBP/VHH5 interaction surface that delineates the receptor-binding area. A glycerol molecule, observed in the 1.7-Å resolution structure of RBP, was found to bind tightly (Kd = 0.26 μM) in a crevice located in this area. Other saccharides bind RBP with comparable high affinity. These data prove the saccharidic nature of the bacterial receptor recognized by phage p2 and identify the position of its binding site in the RBP head domain.

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