Identification of proteins in a Salmonella SPI-1 type III secretion injectisome basal body mutant

We determined the cryo-EM structure of a secretion incompetent PrgH130-392 type III secretion injectisome basal body mutant at 6.3 Å. The map shows no density attributable to the inner rod or needle and the periplasmic gate in a closed conformation. We used LC-MS/MS to idensitfy the constituent proteins showing the predominant presence of the major inner- and outer basal body proteins (PrgH+PrgK and InvG respectively) and export apparatus protein SpaP.