title: Finding of the low molecular weight inhibitors of resuscitation promoting factor enzymatic and resuscitation activity.
abstract: BACKGROUND
  Resuscitation promoting factors (RPF) are secreted proteins involved in reactivation of dormant actinobacteria, including Mycobacterium tuberculosis. They have been considered as prospective targets for the development of new anti-tuberculosis drugs preventing reactivation of dormant tubercle bacilli, generally associated with latent tuberculosis. However, no inhibitors of Rpf activity have been reported so far. The goal of this study was to find low molecular weight compounds inhibiting the enzymatic and biological activities of Rpfs.
  
  
  RESULTS
  Here we describe a novel class of 2-nitrophenylthiocyanates (NPT) compounds that inhibit muralytic activity of Rpfs with IC(50) 1-7 microg/ml. Fluorescence studies revealed interaction of active NPTs with the internal regions of the Rpf molecule. Candidate inhibitors of Rpf enzymatic activity showed a bacteriostatic effect on growth of Micrococcus luteus (in which Rpf is essential for growth protein) at concentrations close to IC(50). The candidate compounds suppressed resuscitation of dormant ("non-culturable") cells of M. smegmatis at 1 microg/ml or delayed resuscitation of dormant M. tuberculosis obtained in laboratory conditions at 10 microg/ml. However, they did not inhibit growth of active mycobacteria under these concentrations.
  
  
  CONCLUSIONS
  NPT are the first example of low molecular weight compounds that inhibit the enzymatic and biological activities of Rpf proteins.
authors.affiliation: A. N. Bach Institute of Biochemistry, RAS, Moscow, Russia.
authors.forename: Galina R
authors.initials: GR
authors.lastname: Demina
authors.forename: Vadim A
authors.initials: VA
authors.lastname: Makarov
authors.forename: Vadim D
authors.initials: VD
authors.lastname: Nikitushkin
authors.forename: Olga B
authors.initials: OB
authors.lastname: Ryabova
authors.forename: Galina N
authors.initials: GN
authors.lastname: Vostroknutova
authors.forename: Elena G
authors.initials: EG
authors.lastname: Salina
authors.forename: Margarita O
authors.initials: MO
authors.lastname: Shleeva
authors.forename: Anna V
authors.initials: AV
authors.lastname: Goncharenko
authors.forename: Arseny S
authors.initials: AS
authors.lastname: Kaprelyants
mesh_terms: D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry; D016207:Cytokines / Q000037:antagonists & inhibitors* / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000032:analysis* / Q000494:pharmacology*; D005453:Fluorescence; D008826:Microbial Sensitivity Tests; D008970:Molecular Weight; D020102:Mycobacterium smegmatis / Q000166:cytology / Q000187:drug effects / Q000254:growth & development; D009169:Mycobacterium tuberculosis / Q000166:cytology* / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D017433:Protein Structure, Secondary; D013861:Thiocyanates / Q000138:chemical synthesis / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D016207:Cytokines; D004791:Enzyme Inhibitors; D013861:Thiocyanates; C113704:resuscitation-promoting factor, bacteria