Finding of the low molecular weight inhibitors of resuscitation promoting factor enzymatic and resuscitation activity.
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.
Demina
Galina R
GR
A. N. Bach Institute of Biochemistry, RAS, Moscow, Russia.
Makarov
Vadim A
VA
Nikitushkin
Vadim D
VD
Ryabova
Olga B
OB
Vostroknutova
Galina N
GN
Salina
Elena G
EG
Shleeva
Margarita O
MO
Goncharenko
Anna V
AV
Kaprelyants
Arseny S
AS
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
D001426:Bacterial Proteins; D016207:Cytokines; D004791:Enzyme Inhibitors; D013861:Thiocyanates; C113704:resuscitation-promoting factor, bacteria