ao8b03582_si_001.pdf (3.08 MB)
Ameloblastin Binds to Phospholipid Bilayers via a Helix-Forming Motif within the Sequence Encoded by Exon 5
Version 2 2019-09-11, 17:49
Version 1 2019-02-28, 14:05
journal contribution
posted on 2019-09-11, 17:49 authored by Jingtan Su, Natalie C. Kegulian, Rucha Arun Bapat, Janet Moradian-OldakAmeloblastin (Ambn), the most abundant non-amelogenin enamel protein,
is intrinsically disordered and has the potential to interact with
other enamel proteins and with cell membranes. Here, through multiple
biophysical methods, we investigated the interactions between Ambn
and large unilamellar vesicles (LUVs), whose lipid compositions mimicked
cell membranes involved in epithelial cell-extracellular matrix adhesion.
Using a series of Ambn Trp/Phe variants and Ambn mutants, we further
showed that Ambn binds to LUVs through a highly conserved motif within
the sequence encoded by exon 5. Synthetic peptides derived from different
regions of Ambn confirmed that the sequence encoded by exon 5 is involved
in LUV binding. Sequence analysis of Ambn across different species
showed that the N-terminus of this sequence contains a highly conserved
motif with a propensity to form an amphipathic helix. Mutations in
the helix-forming sequence resulted in a loss of peptide binding to
LUVs. Our in vitro data suggest that Ambn binds the lipid membrane
directly through a conserved helical motif and have implications for
biological events such as Ambn-cell interactions, Ambn signaling,
and Ambn secretion via secretory vesicles.