Acts as an anti-CsrA protein, binds CsrA and prevents it from repressing translation of its target genes, one of which is flagellin. Binds to flagellin and participates in the assembly of the flagellum. Allosterically inhibits CsrA binding to mRNA in a non-competitive fashion by preventing CsrA binding to the 5'-UTR (PubMed:27551070). Monomer (PubMed:27551070). One copy interacts with the each alpha-helical wing of the CsrA homodimer, yielding a FliW-CsrA(2)-FliW complex (PubMed:27551070). Comparison with a CsrA-mRNA structure (2JPP) suggests CsrA cannot bind both mRNA and FliW at the same time (PubMed:27551070). Interacts with flagellin (By similarity). Belongs to the FliW family.