Complete 1H, 13C and 15N NMR assignments for donor-strand complemented AafA, the major pilin of aggregative adherence fimbriae (AAF/II) from enteroaggregative E. coli

Abstract

Aggregative adherence fimbriae (AAF) are the primary adhesive factors of enteroaggregative Escherichia coli (EAEC) and are required for intestinal colonization. They mediate binding to extracellular matrix proteins of the enteric mucosa and display proinflammatory effects on epithelial cells in vitro. Among the simplest of bacterial fimbriae, these passive hairlike appendages are composed primarily of a single 16-kDa structural and adhesive subunit, AafA. Oligomerization occurs by incorporating the N-terminal strand of each AafA subunit into an otherwise incomplete β-sheet of an adjacent AafA subunit. We have engineered a highly soluble AafA monomer by positioning the N-terminal “donor strand” at the C-terminus, following a turn and short linker that were introduced to allow access of the donor strand to the recipient cleft of the same subunit. The resulting “donor-strand complemented” AafA subunit, or AafA-dsc folds autonomously, is monodisperse in solution, and yields high quality NMR spectral data. Here, we report the ¹H, ¹³C, and ¹⁵N chemical shift assignments for AafA-dsc.