<b>Membrane binding properties of the cytoskeletal protein bactofilin</b>

Bactofilins are a widespread family of cytoskeletal proteins with important roles in bacterial morpho-1 genesis, chromosome organization and motility. They polymerize in a nucleotide-independent manner, 2 forming non-polar filaments that are typically associated with the cytoplasmic membrane. Membrane 3 binding was suggested to be mediated by a short N-terminal peptide, but the underlying mechanism and 4 the conservation of this interaction determinant among bacteria remain unclear. Here, we use the bacto-5 filin homolog BacA of the stalked bacterium <i>Caulobacter crescentus </i>as a model to analyze the membrane-6 binding behavior of bactofilins. Based on site-directed mutagenesis of the N-terminal region, we identify 7 the full membrane-targeting sequence of BacA (MFSKQAKS) and identify amino acid residues that are 8 critical for its function <i>in vivo </i>and <i>in vitro</i>. Molecular dynamics simulations then provide detailed insight 9 into the molecular mechanism underlying the membrane affinity of this peptide.