A novel solenoid fold in the cell wall anchoring domain of the pneumococcal virulence factor LytA

Choline binding proteins are virulence determinants present in several Gram -positive bacteria. Because anchorage of these proteins to the cell wall th rough their choline binding domain is essential for bacterial virulence, th eir release from the cell surface is considered a powerful target for a wea pon against these pathogens. The first crystal structure of a choline bindi ng domain, from the toxin-releasing enzyme pneumococcal major autolysin (Ly tA), reveals a novel solenoid fold consisting exclusively of beta -hairpins that stack to form a left-handed superhelix. This unique structure is main tained by choline molecules at the hydrophobic interface of consecutive hai rpins and maybe present in other choline binding proteins that share high h omology to the repeated motif of the domain.