Revisiting the host adhesion determinants of Streptococcus thermophilus siphophages

Katherine Lavelle (1) , Adeline Goulet (2, 3, 4, 5) , Brian Mcdonnell (1) , Silvia Spinelli (3, 4, 2) , Douwe Van Sinderen (1, 6) , Jennifer Mahony (1, 6) , Christian Cambillau (1, 3, 4, 2)

1 UCC - University College Cork
2 AFMB - Architecture et fonction des macromolécules biologiques
3 CNRS - Centre National de la Recherche Scientifique
4 AMU - Aix Marseille Université
5 LISM - Laboratoire d'ingénierie des systèmes macromoléculaires
6 APC Microbiome Institute [Cork]

Available 3D structures of bacteriophage modules combined with predictive bioinformatic algorithms enabled the identification of adhesion modules in 57 siphophages infecting Streptococcus thermophilus (St). We identified several carbohydrate-binding modules (CBMs) in so-called evolved distal tail (Dit) and tail-associated lysozyme (Tal) proteins of St phage baseplates. We examined the open reading frame (ORF) downstream of the Tal-encoding ORF and uncovered the presence of a putative p2-like receptor-binding protein (RBP). A 21 A resolution electron microscopy structure of the baseplate of cos-phage STP1 revealed the presence of six elongated electron densities, surrounding the core of the baseplate, that harbour the p2-like RBPs at their tip. To verify the functionality of these modules, we expressed GFP-or mCherry-coupled Tal and putative RBP CBMs and observed by fluorescence microscopy that both modules bind to their corresponding St host, the putative RBP CBM with higher affinity than the Tal-associated one. The large number of CBM functional domains in St phages suggests that they play a contributory role in the infection process, a feature that we previously described in lactococcal phages and beyond, possibly representing a universal feature of the siphophage host-recognition apparatus.

Domaines: Sciences du Vivant [q-bio]

Katherine Lavelle, Adeline Goulet, Brian Mcdonnell, Silvia Spinelli, Douwe Van Sinderen, et al.. Revisiting the host adhesion determinants of Streptococcus thermophilus siphophages. Microbial Biotechnology, 2020, 13 (6), pp.1765 - 1779. ⟨10.1111/1751-7915.13593⟩. ⟨hal-03049551⟩