The LysR-type transcriptional regulator CysB controls the repression of hslJ transcription in Escherichia coli

The LysR-type transcriptional regulator (LTTR) CysB is a transcription factor in Escherichia coli cells, where as a homotetramer it binds the target promoter regions and activates the genes involved in sulphur utilization and sulphonate-sulphur metabolism, while negatively autoregulating its own transcription. The hslJ gene was found to be negatively regulated by CysB and directly correlated with novobiocin resistance of the bacterium. cysB mutants showed upregulation of the hslJ:: lacZ gene fusion and exhibited increased novobiocin resistance. In this study the hslJ transcription start point and the corresponding putative sigma(70) promoter were determined. The hslJ promoter region was defined by employing different hslJ-lacZ operon fusions, and transcription of the hslJ gene was shown to be subject to both repression imposed by the CysB regulator and direct or indirect autogenous negative control. These two regulations compete to some extent but they are not mutually exclusive. CysB acts as a direct repressor of hslJ transcription and binds the hslJ promoter region that carries the putative CysB repressor site. This CysB binding, apparently responsible for repression, is enhanced in the presence of the ligand N-acetylserine (NAS), hitherto considered to be a positive cofactor in CysB-mediated gene regulations. Interallelic complementation of characterized CysB mutants I33N and S277Ter partially restored the repression of hslJ transcription and the consequent novobiocin sensitivity, but did not complement the cysteine auxotrophy

Identification of the CysB-regulated gene, hslJ, related to the Escherichia coli novobiocin resistance phenotype

The cysB gene product is a LysR-type regulatory protein required for expression of the cys regulon. cysB mutants of Escherichia coli and Salmonella, along with being auxotrophs for the cysteine, exhibit increased resistance to the antibiotics novobiocin (Nov) and mecillinam. In this work, by using lambdaplacMu9 insertions creating random lacZ fusions, we identify a gene, hslJ, whose expression appeared to be increased in cysB mutants and needed for Nov resistance. Measurements of the hslJ::IacZ gene fusion expression demonstrated that the hslJ gene is negatively regulated by CysB. In addition we observe the negative autogenous control of HslJ. When the control imposed by CysB is lifted in the cysB mutant, the elevation of Nov resistance can be achieved only in the presence of wild-type hslJ allele. A double cysB hslJ mutant restores the sensitivity to Nov. Overexpression of the wild-type HslJ protein either in a cysB(+) or a cys(B-) background increases the level of Nov resistance indicating that hslJ product is indeed involved in accomplishing this phenotype. The hslJ::OmegaKan allele encodes the C-terminaly truncated mutant protein HslJ Q121Ter which is not functional in achieving the Nov resistance but when overexpressed induces the psp operon. Finally, we found that inactivation of hslJ does not affect the increased resistance to mecillinam in cysB mutants

Soluble sPD-L1 and serum amyloid A1 as potential biomarkers for lung cancer

Background: The objective of this prospective study was to evaluate whether soluble programmed cell death-1/programmed cell death-ligand 1 (PD-1/PD-L1) and serum amyloid A1 (SAA1) are potential diagnostic, predictive or prognostic biomarkers in lung cancer. Methods: Lung cancer patients (n=115) with advanced metastatic disease, 101 with non-small cell lung cancer, NSCLC (77 EGFR wild-type NSCLC patients on chemotherapy, 15 EGFR mutation positive adenocarcinoma patients, 9 patients with mPD-L1 Expression >= 50% NSCLC - responders to immunotherapy), and 14 patients with small cell lung cancer (SCLC) were examined. ELISA method was used to determine sPD-L1 and SAA1 concentrations in patients' plasma. Results: Significantly higher blood concentrations of sPD-L1 and SAA1 were noted in lung cancer patients compared with a healthy control group. In PD-L1 + NSCLC patients, a significantly higher sPD-L1 level was noticed compared to any other lung cancer subgroup, as well as the highest average SAA1 value compared to other subgroups. Conclusions: It seems that sPD-1/PD-L1 might be a potential biomarker, prognostic and/or predictive, particularly in patients treated with immunotherapy. Serum amyloid A1 has potential to act as a good predictor of patients' survival, as well as a biomarker of a more advanced disease, with possibly good capability to predict the course of disease measured at different time points

Metal-dielectric photonic crystal for the enhancement of solar-blind ultraviolet silicon photodiodes

We report the fabrication of metal-dielectric photonic crystals as bandpass filter for the UV riadiation with a sidelobe suppression in excess of 4 orders of magnitude. The metal-dielectrics were designed for the enhcancement of the operation of UV photodiodes and for the use of Si PIN photodiodes as solar-blind devices. The bandpass filters were fabricated by RF sputtering of alternating SiO2 and silver layers

Genetic aspect of cystic fibrosis [Genetski aspekt cistične fibroze]

Cystic fibrosis (CF) is an autosomal recessive disease. The gene responsible for cystic fibrosis is located on the long arm of chromosome 7 (7q31) and it carries information for CFTR protein (Cystic Fibrosis Conductance Regulator Protein). This protein is located in the epithelial cell membrane and contributes in chloride transportation. More than 800 mutations have been discovered in CFTR gene by now. The most frequent mutation is deletion of 3 bp in exon 10, which leads to absence of phenylalanine on position ΔF508 in the protein and is marked as 508. In our paper 3 patients (2 male and 1 female children) with CF are presented. We analyzed the presence of mutations in CFTR gene in our patients and the members of their families. DNA was isolated from peripheral blood lymhocytes of our patients and members of their families. Using direct diagnostic methods, the presence of the following mutations has been determined. ΔF508 - by heteroduplex method, G551D and R553X by polymorphism length restriction fragments analysis, G542X, N1303K, 621 + 1GAT, R117X by method of specific PCR mutagenesis. We analyzed exons 4, 10 and 21 within CFTR gene by indirect diagnostics - DGGE (denaturating gradient gel electrophoresis). Automatic sequencing identifies the changes noticed in these exons. The female patient with a respiratory form of the disease is mixed heterozygote for N103K and 525delT mutations. Her father and sister are heterozygous for N1303K mutation and mother is heterozygous for 525delT mutation. These two types of mutations carried by our parents seriously damage the function of CFTR protein processing. 525delT is a "de novo" mutation and has still not been describe on functional level. It is assumed to lead to the absence of CFTR protein synthesis. Today, prenatal genotype diagnosis of CF from trophoblasts is possible. By using prenatal genotype diagnosis CF has been excluded in our female patient's younger sister

A consideration of transparent metal structures for subwavelength diffraction management

We considered theoretically and experimentally one-dimensional multilayered metallodielectric nanofilms with nanometric thickness for imaging below the diffraction limit. We investigated their behavior in the ultravioled and visible spectrum from the point of view of near field optics, but also considered some of their properties in the far field. We designed our structures using the transfer matrix method and utilized RF sputtering to fabricate them. We consider some possible approaches to extract optical information from such multilavers

In vitro and in vivo methodologies for studying the sigma 54-dependent transcription

Here we describe approaches and methods to assaying in vitro the major variant bacterial sigma factor, Sigma 54 (σ54), in a purified system. We include the complete transcription system, binding interactions between σ54 and its activators, as well as the self-assembly and the critical ATPase activity of the cognate activators which serve to remodel the closed promoter complexes. We also present in vivo methodologies that are used to study the impact of physiological processes, metabolic states, global signalling networks, and cellular architecture on the control of σ54-dependent gene expression