The Cyclopropane Fatty Acid Synthase Mediates Antibiotic Resistance and Gastric Colonization of Helicobacter pylori.

Cyclopropane fatty acids (CFAs) are synthetized by the addition of a methylene group from -adenosyl-l-methionine across the carbon-carbon double bonds of unsaturated fatty acid chains of membrane phospholipids. This fatty acid cyclopropanation, catalyzed by the CFA synthase (CfaS) enzyme, occurs in many bacteria, including the human pathogen Although the cyclopropane modification was reported to play a key role in the adaptation in response to environmental stress, its role in remains unknown. In this study, we showed that HP0416 encodes a functional CfaS. The enzyme was demonstrated to be required for acid resistance, antibiotic resistance, intracellular survival and mouse gastric colonization, and cell membrane integrity. Moreover, the tool compound dioctylamine, which acts as a substrate mimic, directly inhibits the CfaS function of , resulting into sensitivity to acid stress, increased antibiotic susceptibility, and attenuated abilities to avoid macrophage killing and to colonize mouse stomachs. These results validate CfaS as a promising antibiotic target and provide new potentials for this recognized target in future anti- drug discovery efforts. The increasing prevalence of multidrug-resistant strains has created an urgent need for alternative therapeutic regimens that complement the current antibiotic treatment strategies for eradication; however, this is greatly hampered due to a lack of "druggable" targets. Although the CFAs are present in cytoplasmic membranes at high levels, their physiological role has not been established. In this report, deletion of the CFA synthase CfaS was shown to attenuate acid and drug resistance, immune escape, and gastric colonization of These findings were validated by inhibition of the CfaS activity with the tool compound dioctylamine. These studies identify this enzyme as an attractive target for further drug discovery efforts against .