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Publication Abstract from PubMed

Myoviruses, bacteriophages with T4-like architecture, must contract their tails prior to DNA release. However, quantitative kinetic data on myovirus particle opening are lacking, although they are promising tools in bacteriophage-based antimicrobial strategies directed against Gram-negative hosts. For the first time, we show time-resolved DNA ejection from a bacteriophage with a contractile tail, the multi-O-antigen specific Salmonella myovirus Det7. DNA release from Det7 was triggered by lipopolysaccharide (LPS) O-antigen receptors and notably slower than in non-contractile tailed siphoviruses. Det7 showed two individual kinetic steps for tail contraction and particle opening. Our in vitro studies showed that highly specialized tailspike proteins (TSPs) are necessary to attach the particle to LPS. A P22-like TSP confers specificity for the S. Typhimurium O-antigen. Moreover, crystal structure analysis at 1.63 A resolution confirmed that Det7 recognized the S. Anatum O-antigen via an ε15-like TSP, DettilonTSP. DNA ejection triggered by LPS from either host showed similar velocities, particle opening is thus a process independent of O-antigen composition and the recognizing TSP. In Det7, at permissive temperatures TSPs mediate O-antigen cleavage and couple cell surface binding with DNA ejection, but no irreversible adsorption occurred at low temperatures. This finding was in contrast to short-tailed Salmonella podoviruses, illustrating that tailed phages use common particle opening mechanisms, but have specialized into different infection niches.

Time-resolved DNA release from an O-antigen specific Salmonella bacteriophage with a contractile tail.,Broeker NK, Roske Y, Valleriani A, Stephan MS, Andres D, Koetz J, Heinemann U, Barbirz S J Biol Chem. 2019 Jun 12. pii: RA119.008133. doi: 10.1074/jbc.RA119.008133. PMID:31189652^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.