FIG 2.

Schematic overview of different bacteriophage entry mechanisms. Several different entry mechanism for nonenveloped (Head-Tail, Corticovirus, and Tectivirus), enveloped (Cystovirus), and filamentous (Enterobacteria phage M13) bacteriophage are shown. Structures are not drawn to scale, and only key structures for viral entry are shown and color coded according to the part they breach during entry, e.g., components responsible for cell wall degradation have the same color as the cell wall indicated in the legend. Associated membrane proteins are indicated as circles. Mechanisms for Gram-positive bacterial hosts are shown on the left, while those Gram-negative hosts are shown on the right. Numbers in parentheses indicate references for the corresponding step (steps without references are putative and inferred by the authors) (see references 50 to 53, 56, 57, 61, 109, 116, and 244 to 246). No Gram-positive hosts are known for corticovirus and cystovirus, and a red X indicates possible interference of the cell wall onto the entry mechanism.