Identification of the minimal cytolytic unit for streptolysin S and an expansion of the toxin family

Conclusions:
The mutagenesis data described herein indicate that the minimal cytolytic unit of SLS encompasses the NPH region of the core peptide. Interestingly, this region is found in all characterized TOMM cytolysins, as well as the novel putative TOMM cytolysins we discovered. We propose that this conserved region represents the defining feature of the SLS-like TOMM family. We demonstrate the cytolytic potential of a Bbsl SLS-like precursor peptide, which has a core region of similar length to the SLS minimal cytolytic unit, when modified with purified SLS biosynthetic enzymes. As such, we speculate that some Borrelia have the potential to produce a TOMM cytolysin, although the biological significance of this finding remains to be determined. In addition to providing new insight into the structure-activity relationships of SLS, this study greatly expands the cytolysin group of TOMMs.

Source: BMC Microbiology - July 24, 2015 Category: Microbiology Authors: Evelyn MolloySherwood CasjensCourtney CoxTucker MaxsonNicole EthridgeGabriele MargosVolker FingerleDouglas Mitchell Source Type: research