Excretion of unassembled hook-associated proteins by Salmonella typhimurium.

Hook-associated proteins (HAPs) were excreted into the culture medium of the Fla+ strain as well as into the growth medium of the filamentless mutants of Salmonella typhimurium. This indicates that the bacteria synthesize HAPs excessively, beyond the amount required for construction of flagella. The extra HAPs are shed into the culture medium after a definite amount of each HAP has been assembled into the flagellar structure.