title: Analogous mechanisms of resistance to benzothiazinones and dinitrobenzamides in Mycobacterium smegmatis.
abstract: Tuberculosis is still a leading cause of death worldwide. The selection and spread of Mycobacterium tuberculosis multidrug-resistant (MDR-TB) and extensively drug-resistant strains (XDR-TB) is a severe public health problem. Recently, two different classes of chemical series, the benzothiazinones (BTZ) and the dinitrobenzamide (DNB) derivatives have been found to be highly active against M. tuberculosis, including XDR-TB strains. The target of BTZs is DprE1 protein which works in concert with DprE2 to form the heteromeric decaprenylphosphoryl-β-D-ribose 2'-epimerase, involved in Decaprenyl-Phospho-Arabinose (DPA) biosynthesis. Interestingly, it has been shown that the DNBs block the same pathway thus suggesting that both drugs could share the same target. Moreover, in Mycobacterium smegmatis the overexpression of the NfnB nitroreductase led to the inactivation of the BTZs by reduction of a critical nitro-group to an amino-group. In this work several spontaneous M. smegmatis mutants resistant to DNBs were isolated. Sixteen mutants, showing high levels of DNB resistance, exhibited a mutation in the Cys394 of DprE1. Using fluorescence titration and mass spectrometry it has been possible to monitor the binding between DprE1 and DNBs, achieving direct evidence that MSMEG_6382 is the cellular target of DNBs in mycobacteria. Additionally, M. smegmatis mutants having low levels of resistance to DNBs harbor various mutations in MSMEG_6503 gene encoding the transcriptional repressor of the nitroreductase NfnB. By LC/MS analysis it has been demonstrated that NfnB is responsible for DNB inactivation. Taken together, our data demonstrate that both DNB and BTZ drugs share common resistance mechanisms in M. smegmatis.
authors: Dipartimento di Genetica e Microbiologia, Università degli Studi di Pavia, Pavia, Italy.
authors: Ana Luisa de Jesus Lopes
authors: AL
authors: Ribeiro
authors: Giulia
authors: G
authors: Degiacomi
authors: Fanny
authors: F
authors: Ewann
authors: Silvia
authors: S
authors: Buroni
authors: Maria Loreto
authors: ML
authors: Incandela
authors: Laurent R
authors: LR
authors: Chiarelli
authors: Giorgia
authors: G
authors: Mori
authors: Jaeseung
authors: J
authors: Kim
authors: Monica
authors: M
authors: Contreras-Dominguez
authors: Young-Sam
authors: YS
authors: Park
authors: Sung-Jun
authors: SJ
authors: Han
authors: Priscille
authors: P
authors: Brodin
authors: Giovanna
authors: G
authors: Valentini
authors: Menico
authors: M
authors: Rizzi
authors: Giovanna
authors: G
authors: Riccardi
authors: Maria Rosalia
authors: MR
authors: Pasca
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001549:Benzamides / Q000737:chemistry / Q000627:therapeutic use; D015153:Blotting, Western; D020134:Catalytic Domain; D002853:Chromatography, Liquid; D004136:Dinitrobenzenes / Q000737:chemistry / Q000627:therapeutic use; D009165:Mycobacterium Infections, Nontuberculous / Q000188:drug therapy*; D020102:Mycobacterium smegmatis / Q000187:drug effects*; D009601:Nitroreductases / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D019998:Racemases and Epimerases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013843:Thiazines / Q000737:chemistry / Q000627:therapeutic use; D018088:Tuberculosis, Multidrug-Resistant / Q000188:drug therapy* / Q000382:microbiology*
chemical_list: C543931:1,3-benzthiazinan-4-one; D000900:Anti-Bacterial Agents; D001549:Benzamides; D004136:Dinitrobenzenes; D012333:RNA, Messenger; D013843:Thiazines; D009601:Nitroreductases; D019998:Racemases and Epimerases