Peptidoglycan fragments stimulate resuscitation of "non-culturable" mycobacteria.

Resuscitation promoting factors (Rpfs), belonging to a family of secreted actinobacterial proteins with predicted peptidoglycan (PG) hydrolytic activities, participate in the reactivation of dormant cells. In the present study we demonstrate that a recombinant truncated form of Micrococcus luteus Rpf hydrolyzes isolated PG of Mycobacterium smegmatis and Mycobacterium tuberculosis liberating PG fragments of different size. These fragments possess stimulatory activity toward "non-culturable" dormant M. smegmatis and M. tuberculosis cells, similar to the activity of recombinant Rpf. Relatively large PG fragments (0.1-0.5 μm) obtained either by Rpf digestion or by PG ultrasonication revealed resuscitation activities when added in concentrations 0.1-0.2 μg/ml to the resuscitation medium. It is suggested that PG fragments could either directly activate the resuscitation pathway of dormant mycobacteria or serve as a substrate for endogenous Rpf, resulting in low molecular weight products with resuscitation activity. Whilst both suggestions are plausible, it was observed that PG-dependent resuscitation activity was suppressed by means of a specific Rpf inhibitor (4-benzoyl-2-nitrophenylthiocyanate), which provides additional support for the second of these possibilities.

Citation

Vadim D Nikitushkin, Galina R Demina, Margarita O Shleeva, Arseny S Kaprelyants. Peptidoglycan fragments stimulate resuscitation of "non-culturable" mycobacteria. Antonie van Leeuwenhoek. 2013 Jan;103(1):37-46

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PMID: 22864992

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