The Gene Is Required for the Resistance of to Antimicrobial Peptides and Virulence in .

Antimicrobial peptides (AMPs) are essential effectors of the host innate immune system and they represent promising molecules for the treatment of multidrug resistant microbes. A better understanding of microbial resistance to these defense peptides is thus prerequisite for the control of infectious diseases. Here, using a random mutagenesis approach, we identify the gene, encoding an internal molecular ruler that controls flagella hook length, as an essential element for resistance to AMPs in . Unlike its parental strain, that is highly virulent to both wild-type and AMPs deficient mutant flies, the deletion mutant is only lethal to the latter's. In agreement with its conserved function, the mutant is non-flagellated and exhibits highly compromised motility. However, comparative analysis of the mutant phenotype to that of a mutant, in which the genes encoding flagella proteins are interrupted, indicate that FliK-dependent resistance to AMPs is independent of flagella assembly. As a whole, our results identify FliK as an essential determinant for virulence in and provide new insights on the mechanisms underlying bacteria resistance to AMPs.