Mycobacterium smegmatis msmeg_3314 is involved in pyrazinamide and fluoroquinolones susceptibility via NAD+/NADH dysregulation

Aim: To identify and characterize new mycobacterium pyrazinamide (PZA) resistance genes in addition to pncA, rpsA and panD. Materials & methods: To screen a Tn7 M. smegmatis mc(2)155 transposon library using 50 mu M PZA and a PZA hypersensitive mutant (M492) was obtained. MIC was further used to confirm the hypersensitivity of M492 mutant by culturing the mutant in Middlebrook 7H9 liquid medium at 37 degrees C. Results:msmeg_3314 is the gene underlying the hypersensitive phenotype of mutant M492. The observed resistance to PZA and fluoroquinolones involved the alteration of Mycobacterium cell wall permeability and the dissipation of the proton motive force. NAD(+)/NADH dysregulation and attenuated glyoxylate shunt might underlie the declined scavenging capacity of reactive oxygen species in the msmeg_3314-deficient mutants. Conclusion:msmeg_ 3314 is a novel gene involved in pyrazinamide resistance and might be a new candidate for drugs target.