Molecular insights on the recognition of a Lactococcus lactis cell wall pellicle by the phage 1358 receptor binding protein.
The Gram-positive bacterium Lactococcus lactis is used for the production of cheeses and other fermented dairy products. Accidental infection of L. lactis cells by virulent lactococcal tailed phages is one of the major risks of fermentation failures in industrial dairy factories. Lactococcal phage 1358 possesses a host range limited to a few L. lactis strains and strong genomic similarities to Listeria phages. We report here the X-ray structures of phage 1358 receptor binding protein (RBP) in complex with monosaccharides. Each monomer of its trimeric RBP is formed of two domains: a "shoulder" domain linking the RBP to the rest of the phage and a jelly roll fold "head/host recognition" domain. This domain harbors a saccharide binding crevice located in the middle of a monomer. Crystal structures identified two sites at the RBP surface, ∼8 Å from each other, one accommodating a GlcNAc monosaccharide and the other accommodating a GlcNAc or a glucose 1-phosphate (Glc1P) monosaccharide. GlcNAc and GlcNAc1P are components of the polysaccharide pellicle that we identified at the cell surface of L. lactis SMQ-388, the host of phage 1358. We therefore modeled a galactofuranose (Galf) sugar bridging the two GlcNAc saccharides, suggesting that the trisaccharidic motif GlcNAc-Galf-GlcNAc (or Glc1P) might be common to receptors of genetically distinct lactococcal phages p2, TP091-1, and 1358. Strain specificity might therefore be elicited by steric clashes induced by the remaining components of the pellicle hexasaccharide. Taken together, these results provide a first insight into the molecular mechanism of host receptor recognition by lactococcal phages.


OBJECTIVE
Siphophages infecting the Gram-positive bacterium Lactococcus lactis are sources of milk fermentation failures in the dairy industry. We report here the structure of the pellicle polysaccharide from L. lactis SMQ-388, the specific host strain of phage 1358. We determined the X-ray structures of the lytic lactococcal phage 1358 receptor binding protein (RBP) in complex with monosaccharides. The positions and nature of monosaccharides bound to the RBP are in agreement with the pellicle structure and suggest a general binding mode of lactococcal phages to their pellicle saccharidic receptor.
Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Aix-Marseille Université, Marseille, France Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Centre National de la Recherche Scientifique, Marseille, France.
Carine
C
Farenc
Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Aix-Marseille Université, Marseille, France Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Centre National de la Recherche Scientifique, Marseille, France.
Silvia
S
Spinelli
Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario, Canada.
Evgeny
E
Vinogradov
Groupe de Recherche en Écologie Buccale and Félix d'Hérelle Reference Center for Bacterial Viruses, Faculté de Médecine Dentaire, Université Laval, Québec, Canada.
Denise
D
Tremblay
Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Aix-Marseille Université, Marseille, France Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Centre National de la Recherche Scientifique, Marseille, France.
Stéphanie
S
Blangy
Université Lille Nord de France, Lille, France Université du Littoral-Côte d'Opale, Boulogne-sur-Mer, France.
Irina
I
Sadovskaya
Groupe de Recherche en Écologie Buccale and Félix d'Hérelle Reference Center for Bacterial Viruses, Faculté de Médecine Dentaire, Université Laval, Québec, Canada Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Québec, Canada sylvain.moineau@bcm.ulaval.ca cambillau@afmb.univ-mrs.fr.
Sylvain
S
Moineau
Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Aix-Marseille Université, Marseille, France Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Centre National de la Recherche Scientifique, Marseille, France sylvain.moineau@bcm.ulaval.ca cambillau@afmb.univ-mrs.fr.
Christian
C
Cambillau
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001435:Bacteriophages / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000821:virology*; D018360:Crystallography, X-Ray; D013294:Lactococcus lactis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000821:virology*; D008958:Models, Molecular; D011485:Protein Binding; D011991:Receptors, Virus / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D011991:Receptors, Virus; D014764:Viral Proteins