PlyC, a novel bacteriophage lysin for compartment-dependent proteomics of group A streptococci.

Streptococcus pyogenes (Spy) (group A streptococci) is an important and exclusively human bacterial pathogen, which uses secreted and surface-associated proteins to circumvent the innate host defense mechanisms and to adhere and internalize into host cells. Thus, investigation of the bacterial extracellular compartments, including secreted and cell wall-associated subproteomes, is crucial for understanding adherence, invasion, and internalization mechanisms as major steps of Spy pathogenesis. Here, we compared a bacteriophage encoded cell wall hydrolase, PlyC, a multimeric lysin of the C1 bacteriophage, with the established glycosidase, mutanolysin, from Streptomyces globisporus for their suitability to efficiently digest Spy cell walls and release cell wall-anchored Spy proteins for subsequent proteome research. Our results show that PlyC is superior for cell wall protein extraction compared to mutanolysin due to its higher activity and specificity as an N-acetylmuramoyl-L-alanine amidase. Furthermore, our experimental design allowed us to delineate the actual localization of the proteins despite contamination with intracellular proteins.