Knockout oftusAfacilitates flagella formation and cationic antimicrobial resistance by disrupting Fur transcriptional regulation inEscherichia coli

tRNA 2-thiouridine synthesizing protein A (TusA), a sulfur-carrier protein, plays a crucial role in tRNA sulfur modification. Recent studies have reported thattusAdeficiency affects iron-sulfur (Fe-S) homeostasis and cluster formation inEscherichia coli; however, its association with this phenotype remains unclear. In this study, we analyzed the phenotype oftusA-deficientE. coli(ΔtusA) and its underlying mechanisms using RNA sequencing. We observed thattusAdeletion disrupted the expression of genes regulated by the ferric uptake regulator Fur or Fur-regulated transcription factors (flagellar transcriptional regulators D and C [FlhDC] and fumarate and nitrate reduction regulator [Fnr]). Increased expression offlhDC, which is the master regulator of flagellar genes facilitated flagella formation even under conditions in which the wild-type formed few flagella. Additionally, ΔtusAwas resistant to cationic antibacterial agents, such as cetyltrimethylammonium bromide, cetylpyridinium chloride, and protamine sulfate. This resistance is associated with the increased expression ofompXorompF, regulated by Fur and Fnr, respectively. Notably, both enhanced flagella formation and resistance to cationic antibacterial agents caused bytusAdeletion were abolished in thefur-deficient background. These findings indicate that impaired expression of thefurregulon, possibly because of impaired Fe-S cluster formation, induces multiple phenotypic alterations in ΔtusA.