The FliI ATPase couples ATP hydrolysis to substrate switching in bacterial flagellar type-III secretion.

ABSTRACT: Bacterial flagella are assembled by a specialized type-III secretion system that exports structural subunits in a defined order. While the ATPase FliI is known to couple ATP hydrolysis to substrate translocation, its role in the transition between early and late secretion stages has remained unclear. Here, we systematically analyzed Salmonella enterica strains with mutations in the catalytic domain of FliI and found that early substrate export and hook-basal body formation can proceed with minimal FliI ATPase activity, whereas efficient triggering of the substrate specificity switch and late substrate export requires near-wild-type activity levels. Mutant strains showed delayed gene expression from class 3 promoters, prolonged early secretion, and impaired flagellar filament assembl

SUBMITTER: Einenkel R 

PROVIDER: S-EPMC12802181 | biostudies-literature | 2026 Jan

REPOSITORIES: biostudies-literature