The Ectodomain of the Viral Receptor YueB Forms a Fiber That Triggers Ejection of Bacteriophage SPP1 DNA

Abstract

The irreversible binding of bacteriophages to their receptor(s) in the host cell surface triggers release of the naked genome from the virion followed by transit of viral DNA to the host cell cytoplasm. We have purified, for the first time, a receptor from a Gram-positive bacterium that is active to trigger viral DNA ejection in vitro. This extracellular region ("ectodomain") of the Bacillus subtilis protein YueB (YueB780) was a 7 S elongated dimer forming a 36.5-nm-long fiber. YueB780 bound to the tail tip of bacteriophage SPP1. Although a stable receptor-phage interaction occurred between 0 and 37°C, complete blocking of phage DNA release or partial ejection events were observed at temperatures below 15°C. We also showed that the receptor was exposed to the B. subtilis surface. YueB differed structurally from phage receptors from Gram-negative bacteria. Its properties revealed a fiber spanning the full length of the 30-nm-thick peptidoglycan layer. The fiber is predicted to be anchored in the cell membrane through transmembrane segments. These features, highly suitable for a virus receptor in Gram-positive bacteria, are very likely shared by a large number of phage receptors.

Membrane interactions and self‐association of components of the Ess/Type VII secretion system of Staphylococcus aureus

“…Interestingly, essentially the same pattern of EsaA crosslinks was seen whether EssA, EssB or EssC were absent, suggesting that the crosslinked products did not contain any of these proteins. It has been reported that the long extracellular domain of YueB, the Bacillus subtilis homologue of EsaA, forms a highly elongated homo‐dimer 17 and it is therefore likely that the crosslinks seen here correspond to different conformers of a crosslinked EsaA dimer.…”

The First Structure of a Mycobacteriophage, the Mycobacterium abscessus subsp. bolletii Phage Araucaria

“…In Gram-negative (Gram Ϫ ) bacteria (e.g., Escherichia coli), this is observed with phages binding to porins, such as phage T5 (68,69) or phage . In Gram ϩ bacteria, this tail fiber is observed in phage SPP1 (45,66) and lactococcal phage c2 (70), which bind to extracellular components of the type 7 secretion system (T7SS), called, respectively, YueB (66) and PIP (70). In contrast, lactococcal phages of the 936 and P335 families seem to attach exclusively to polysaccharides and bear at their tail end a large macromolecular entity called the baseplate.…”

Structure of bacteriophage SPP1 head-to-tail connection reveals mechanism for viral DNA gating

“…The N terminus, loop ␤2␤2Ј, loop ␤3␤4, and loop ␤6␤7 are located close to gp15, whereas loop ␤2Ј␤3 fills the stopper EM density on the tail side. Incubation of SPP1 with the ectodomain of its cellular receptor (YueB780) (19) leads to efficient DNA release from wild-type phages and virions carrying gp16 with single cysteine mutations, apart from a minor inhibitory effect in case of gp16 Q51C (Fig. 5D).…”

“…We then investigated the effect of covalent intersubunit cross-linking of the stopper in viral genome ejection using a DNase protection assay that quantifies nonejected DNA (9,19).…”

“…Infection is initiated by binding of SPP1 to the surface of the Gram-positive host bacterium. Interaction of the phage tail adsorption apparatus with the receptor YueB generates a signal transmitted along the tail structure to trigger opening of the connector (16,19). Its aperture leads to DNA exit from the capsid through the tail tube to reach the B. subtilis cytoplasm (19).…”