Transfer-messenger RNA controls the translation of cell-cycle and stress proteins in Streptomyces.

The transfer-messenger RNA (tmRNA)-mediated trans-translation mechanism is highly conserved in bacteria and functions primarily as a system for the rescue of stalled ribosomes and the removal of aberrantly produced proteins. Here, we show that in the antibiotic-producing soil bacterium Streptomyces coelicolor, trans-translation has a specialized role in stress management. Analysis of proteins that were carboxy-terminally His(8)-tagged by a recombinant tmRNA identified only 10 targets, including the stress proteins: DnaK heat-shock protein 70, thiostrepton-induced protein A, universal stress protein A, elongation factor Tu3, and the cell-cycle control proteins DasR, SsgA, SsgF and SsgR. Although tmRNA-tagged proteins are degraded swiftly, the translation of dnaK and dasR messenger RNAs (mRNAs) depends fully on tmRNA, whereas transcription is unaffected. The data unveil a surprisingly dedicated functionality for tmRNA, promoting the translation of the same mRNA it targets, at the expense of sacrificing the first nascent protein. In streptomycetes, tmRNA has evolved into a dedicated task force that ensures the instantaneous response to the exposure to stress.

The secreted signaling protein factor C triggers the A-factor response regulon in Streptomyces griseus: overlapping signaling routes.

Members of the prokaryotic genus Streptomyces produce over 60% of all known antibiotics and a wide range of industrial enzymes. A leading theme in microbiology is which signals are received and transmitted by these organisms to trigger the onset of morphological differentiation and antibiotic production. The small gamma-butyrolactone A-factor is an important autoregulatory signaling molecule in streptomycetes, and A-factor mutants are blocked in development and antibiotic production. In this study we showed that heterologous expression of the 324-amino acid secreted regulatory protein Factor C resulted in restoration of development and enhanced antibiotic production of an A-factor-deficient bald mutant of Streptomyces griseus, although the parental strain lacks an facC gene. Proteome analysis showed that in the facC transformant the production of several secreted proteins that belong to the A-factor regulon was restored. HPLC-MS/MS analysis indicated that this was due to restoration of A-factor production to wild-type levels in the transformant. This indicates a connection between two highly divergent types of signaling molecules and possible interplay between their regulatory networks.

[Prevalence of Borrelia burgdorferi sensu lato in Ixodes ricinus population in forests of north-western Poland]. / Ekstensywnosc zakazenia populacji Ixodes ricinus kretkami Borrelia burgdorferi sensu lato w lasach pólnocno-zachodniej Polski.

The ticks Ixodes ricinus were collected during three growing seasons in forested areas of north-western Poland. The ticks were collected by flagging at 30 sites. The specimens collected (nymphs and adults) were subjected, after an appropiate treatment, to indirect immunofluorescence analysis (IFA). In addition, effects of temperature and atmospheric precipitation on the tick infection with the spirochaete Borrelia burgdorferi were investigated based on data supplied by the Institute of Meteorology. A total of 8519 individuals of I. ricinus were collected at the sampling sites within May-October of three consecutive years. The pool of individuals obtained consisted of 7356 nymphs, 559 females, and 604 males. The B. burgdorferri prevalence varied rather widely, from 10 to 19%. Compared to nymphs, adult individuals showed a higher infection rate. A relationship between infection rate and I. ricinus activity in different years and months was studied in detail. The boreliosis risk was found to increase with increasing tick activity. On the other hand, no correlation was found between the meteorological parameters (temperature, precipitation), tick abundance, and the B. burgdorferi infection rate.