Scientific Publications
The cell wall binding domain is a trigger and release factor for the CD27L endolysin targeting Clostridium difficile
PLos Pathogens, 10, e1004228
The bacteriophage ΦCD27 is capable of lysing Clostridium difficile, a pathogenic bacterium that is a major cause for nosocomial infection. A recombinant CD27L endolysin lyses C. difficile in culture, and represents a promising alternative as a bactericide. To better understand the lysis mechanism, we have determined the crystal structure of a proteolytic fragment of the CD27L endolysin. The structure covers the C-terminal domain of the endolysin, and represents a novel fold that is identified in a number of lysins that target Clostridia bacteria. Two dimerization modes are observed in the crystal that are validated to be present for the full length protein in solution by right angle light scattering and SAXS. The structure indicates endolysin cleavage occurs at the stem of the linker connecting the catalytic domain with the C-terminal domain. We show that endolysin cleavage can be inhibited by mutations at the cleavage site and in a dimer interface. These observations indicate that there is a link between the dimerization modes and the autocleavage mechanism. We propose a model for endolysin triggering, where the extended dimer prevails in the cytosol, and a switch to the side-by-side dimer occurs when the endolysin passes through holin lesions into the exterior environment. This leads to the release of the catalytic portion of the endolysin, enabling the efficient digestion of the bacterial cell wall.
PLos Pathogens, 10, e1004228
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