A chromosomal locus encoding a phosphoserine phosphatase- and a truncated MinD-like protein affects differentiation in Streptomyces azureus ATCC14921

6S-Like scr3559 RNA Affects Development and Antibiotic Production in Streptomyces coelicolor

Regulatory RNAs control a number of physiological processes in bacterial cells. Here we report on a 6S-like RNA transcript (scr3559) that affects both development and antibiotic production in Streptomyces coelicolor. Its expression is enhanced during the transition to stationary phase. Strains that over-expressed the scr3559 gene region exhibited a shortened exponential growth phase in comparison with a control strain; accelerated aerial mycelium formation and spore maturation; alongside an elevated production of actinorhodin and undecylprodigiosin. These observations were supported by LC-MS analyses of other produced metabolites, including: germicidins, desferrioxamines, and coelimycin. A subsequent microarray differential analysis revealed increased expression of genes associated with the described morphological and physiological changes. Structural and functional similarities between the scr3559 transcript and 6S RNA, and its possible employment in regulating secondary metabolite production are discussed.

Genomic approach to identifying the putative target of and mechanisms of resistance to mefloquine in mycobacteria

The emergence of mycobacterial resistance to multiple antimicrobials emphasizes the need for new compounds. The antimycobacterial activity of mefloquine has been recently described. Mycobacterium avium, Mycobacterium smegmatis, and Mycobacterium tuberculosis are susceptible to mefloquine in vitro, and activity was evidenced in vivo against M. avium. Attempts to obtain resistant mutants by both in vitro and in vivo selection have failed. To identify mycobacterial genes regulated in response to mefloquine, we employed DNA microarray and green fluorescent protein (GFP) promoter library techniques. Following mefloquine treatment, RNA was harvested from M. tuberculosis H37Rv, labeled with 32P, and hybridized against a DNA array. Exposure to 4x MIC resulted in a significant stress response, while exposure to a subinhibitory concentration of mefloquine triggered the expression of genes coding for enzymes involved in fatty acid synthesis, the metabolic pathway, and transport across the membrane and other proteins of unknown function. Evaluation of gene expression using an M. avium GFP promoter library exposed to subinhibitory concentrations of mefloquine revealed more than threefold upregulation of 24 genes. To complement the microarray results, we constructed an M. avium genomic library under the control of a strong sigma-70 (G13) promoter in M. smegmatis. Resistant clones were selected in 32 microg/ml of mefloquine (wild-type M. avium, M. tuberculosis, and M. smegmatis are inhibited by 8 microg/ml), and the M. avium genes associated with M. smegmatis resistant to mefloquine were sequenced. Two groups of genes were identified: one affecting membrane transport and one gene that apparently is involved in regulation of cellular replication.

Differentiation of neuroblastoma cell line N1E-115 involves several signaling cascades

No systematic searches for differential expression of signaling proteins (SP) in undifferentiated vs. differentiated cell lineages were published and herein we used protein profiling for this purpose. The NIE-115 cell line was cultivated and an aliquot was differentiated with dimethylsulfoxide (DMSO), that is known to lead to a neuronal phenotype. Cell lysates were prepared, run on two-dimensional gel electrophoresis followed by MALDI-TOF-TOF identification of proteins and maps of identified SPs were generated. Seven SPs were comparable, 27 SPs: GTP-binding/Ras-related proteins, kinases, growth factors, calcium binding proteins, phosphatase-related proteins were observed in differentiated NIE-115 cells and eight SPs of the groups mentioned above were observed in undifferentiated cells only. Switching-on/off of several individual SPs from different signaling cascades during the differentiation process is a key to understand mechanisms involved. The findings reported herein are challenging in vitro and in vivo studies to confirm a functional role for deranged SPs.