A systematic overview of strategies for photosensitizer and light delivery in antibacterial photodynamic therapy for lung infections.

Antimicrobial photodynamic therapy (aPDT) emerges as a viable treatment strategy for infections resistant to conventional antibiotics. A complex interplay of factors, including intracellular photosensitizer (PS) accumulation, photochemical reaction type, and oxygen levels, determines the efficacy of aPDT. Recent progress includes the development of modified PSs with enhanced lipophilicity and target-specific strategies to improve bacterial cell wall penetration and targeting.

The accumulation of methylated porphyrins in dormant cells of Mycolicibacterium smegmatis is accompanied by a decrease in membrane fluidity and an impede of the functioning of the respiratory chain.

Transition of Mycolicibacterium smegmatis (Msm) and Mycobacterium tuberculosis to dormancy in vitro is accompanied by an accumulation of free methylated forms of porphyrins (tetramethyl coproporphyrin - TMC) localized in the cell wall of dormant bacteria. A study of the fluorescence anisotropy of BODIPY based fluorescent probes on individual cell level using confocal microscope revealed significant changes in this parameter for BODIPY FL C16 from 0.05 to 0.

The Effect of Antimicrobial Photodynamic Inactivation on the Protein Profile of Dormant Containing Endogenous Porphyrins.

During transition into a dormant state, () cells are able to accumulate free porphyrins that makes them sensitive to photodynamic inactivation (PDI). The formation of dormant cells in a liquid medium with an increased concentration of magnesium (up to 25 mM) and zinc (up to 62 µM) resulted in an increase in the total amount of endogenous porphyrins in dormant cells and their photosensitivity, especially for bacteria phagocytosed by macrophages. To gain insight into possible targets for PDI in bacterial dormant mycobacterial cells, a proteomic profiling with SDS gel electrophoresis and mass spectrometry analysis were conducted.

One-Year Old Dormant, "Non-culturable" Preserves Significantly Diverse Protein Profile.

For adaptation to stressful conditions, () is prone to transit to a dormant, non-replicative state, which is believed to be the basis of the latent form of tuberculosis infection. Dormant bacteria persist in the host for a long period without multiplication, cannot be detected from biological samples by microbiological methods, however, their "non-culturable" state is reversible. Mechanisms supporting very long capacity of mycobacteria for resuscitation and further multiplication after prolonged survival in a dormant phase remain unclear.

Metabolic profiling of dormant Mycolicibacterium smegmatis cells' reactivation reveals a gradual assembly of metabolic processes.

Introduction: Under gradual acidification of the culture medium mycobacterial cells transit into a specific state characterized by low level of metabolic activity and morphological alterations. This state of non-replicative persistence (dormancy) is directly linked to physiological drug resistance, which complicates the efforts to eradicate the latent forms of TB. In order to find new anti-latent TB compounds, the metabolic processes which may occur in the state of dormancy and during the transition into the active state (reactivation) should be characterized.

Protein Composition of Differs Significantly Between Active Cells and Dormant Cells With Ovoid Morphology.

Mycobacteria are able to form dormant cells, which survive for a long time without multiplication. The molecular mechanisms behind prolonged survival of dormant cells are not fully described. In particular, little information is known on biochemical processes which might take place in cells under dormancy.

Benzoylphenyl thiocyanates are new, effective inhibitors of the mycobacterial resuscitation promoting factor B protein.

Background: Resuscitation promoting factors (Rpfs) are the proteins involved in the process of reactivation of the dormant cells of mycobacteria. Recently a new class of nitrophenylthiocyanates (NPTs), capable of inhibiting the biological and enzymatic activities of Rpfs has been discovered. In the current study the inhibitory properties of the compounds containing both nitro and thiocyanate groups alongside with the compounds with the modified number and different spatial location of the substituents are compared.

Overexpression of Adenylyl Cyclase Encoded by the Rv2212 Gene Confers Improved Fitness, Accelerated Recovery from Dormancy and Enhanced Virulence in Mice.

Earlier we demonstrated that the adenylyl cyclase (AC) encoded by the gene plays a key role in the resuscitation and growth of dormant and that overexpression of this gene leads to an increase in intracellular cAMP concentration and prevents the transition of from active growth to dormancy in an extended stationary phase accompanied by medium acidification. We surmised that the homologous gene of (), the main cAMP producer, plays similar physiological roles by supporting, under these conditions, the active state and reactivation of dormant bacteria. To test this hypothesis, we established strain overexpressing and compared its and growth characteristics with a control strain.

Free Trehalose Accumulation in Dormant Cells and Its Breakdown in Early Resuscitation Phase.

Under gradual acidification of growth medium resulting in the formation of dormant , a significant accumulation of free trehalose in dormant cells was observed. According to H- and C-NMR spectroscopy up to 64% of total organic substances in the dormant cell extract was represented by trehalose whilst the trehalose content in an extract of active cells taken from early stationary phase was not more than 15%. Trehalose biosynthesis during transition to the dormant state is provided by activation of genes involved in the OtsA-OtsB and TreY-TreZ pathways (according to RT-PCR).

A product of RpfB and RipA joint enzymatic action promotes the resuscitation of dormant mycobacteria.

Resuscitation-promoting factor proteins (Rpfs) are known to participate in reactivating the dormant forms of actinobacteria. Structural analysis of the Rpf catalytic domain demonstrates its similarity to lysozyme and to lytic transglycosylases - the groups of enzymes that cleave the β-1,4-glycosidic bond between N-acetylmuramic acid (MurNAc) and GlcNAc, and concomitantly form a 1,6-anhydro ring at the MurNAc residue. Analysis of the products formed from mycobacterial peptidoglycan hydrolysis reactions containing a mixture of RpfB and resuscitation-promoting factor interacting protein (RipA) allowed us to identify the suggested product of their action - N-acetylglucosaminyl-β(1 → 4)-N-glycolyl-1,6-anhydromuramyl-L-alanyl-D-isoglutamate.

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.

Resuscitation-promoting factors (Rpf): in search of inhibitors.

Resuscitation promoting factors (Rpf) are a family of proteins secreted by actively growing actinobacteria, including Mycobacterium tuberculosis. Experimental evidence suggests that Rpfs play a distinct role in bacterial resuscitation and re-growth as well as reactivation of chronic tuberculosis in mice. The striking similarity of the Rpfs structure to cell wall hydrolysing enzymes has provided a basis for the development of novel low molecular weight inhibitors of Rpfs activity.

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.

Muralytic activity of Micrococcus luteus Rpf and its relationship to physiological activity in promoting bacterial growth and resuscitation.

The culturability of several actinobacteria is controlled by resuscitation-promoting factors (Rpfs). These are proteins containing a c. 70-residue domain that adopts a lysozyme-like fold.