The katG mRNA of Mycobacterium tuberculosis and Mycobacterium smegmatis is processed at its 5' end and is stabilized by both a polypurine sequence and translation initiation

<p>Abstract</p> <p>Background</p> <p>In <it>Mycobacterium tuberculosis </it>and in <it>Mycobacterium smegmatis </it>the <it>furA</it>-<it>katG </it>loci, encoding the FurA regulatory protein and the KatG catalase-peroxidase, are highly conserved. In <it>M. tuberculosis furA-katG </it>constitute a single operon, whereas in <it>M. smegmatis </it>a single mRNA covering both genes could not be found. In both species, specific 5' ends have been identified: the first one, located upstream of the <it>furA </it>gene, corresponds to transcription initiation from the <it>furA </it>promoter; the second one is the <it>katG </it>mRNA 5' end, located in the terminal part of <it>furA</it>.</p> <p>Results</p> <p>In this work we demonstrate by in vitro transcription and by RNA polymerase Chromatin immunoprecipitation that no promoter is present in the <it>M. smegmatis </it>region covering the latter 5' end, suggesting that it is produced by specific processing of longer transcripts. Several DNA fragments of <it>M. tuberculosis </it>and <it>M. smegmatis </it>were inserted in a plasmid between the <it>sigA </it>promoter and the <it>lacZ </it>reporter gene, and expression of the reporter gene was measured. A polypurine sequence, located four bp upstream of the <it>katG </it>translation start codon, increased beta-galactosidase activity and stabilized the <it>lacZ </it>transcript. Mutagenesis of this sequence led to destabilization of the mRNA. Analysis of constructs, in which the polypurine sequence of <it>M. smegmatis </it>was followed by an increasing number of <it>katG </it>codons, demonstrated that mRNA stability requires translation of at least 20 amino acids. In order to define the requirements for the 5' processing of the <it>katG </it>transcript, we created several mutations in this region and analyzed the 5' ends of the transcripts: the distance from the polypurine sequence does not seem to influence the processing, neither the sequence around the cutting point. Only mutations which create a double stranded region around the processing site prevented RNA processing.</p> <p>Conclusion</p> <p>This is the first reported case in mycobacteria, in which both a polypurine sequence and translation initiation are shown to contribute to mRNA stability. The <it>furA-katG </it>mRNA is transcribed from the <it>furA </it>promoter and immediately processed; this processing is prevented by a double stranded RNA at the cutting site, suggesting that the endoribonuclease responsible for the cleavage cuts single stranded RNA.</p

Tropical response to stratospheric sudden warmings and its modulation by the QBO

Major Stratospheric Sudden Warmings (SSWs) are characterized by a reversal of the zonal mean zonal wind and an anomalous warming in the polar stratosphere that proceeds downward to the lower stratosphere. In the tropical stratosphere, a downward propagating cooling is observed. However, the strong modulation of tropical winds and temperatures by the quasi-biennial oscillation (QBO) renders accurate characterization of the tropical response to SSWs challenging. A novel metric based on temperature variations relative to the central date of the SSW using ERA-Interim data is presented. It filters most of the temperature structure related to the phase of the QBO and provides proper characterization of the SSW cooling amplitude and downward propagation tropical signal. Using this new metric, a large SSW-related cooling is detected in the tropical upper stratosphere that occurs almost simultaneously with the polar cap warming. The tropical cooling weakens as it propagates downward, reaching the lower stratosphere in a few days. Substantial differences are found in the response to SSWs depending on the QBO phase. Similar to what is observed in the polar stratosphere, tropical SSW-associated temperatures persist longer during the west QBO phase at levels above about 40 hPa, suggesting that the signal is mainly controlled by changes in the residual mean meridional circulation associated with SSWs. Conversely, in the lower stratosphere, around 50–70 hPa, enhanced cooling occurs only during QBO east phase. This behavior seems to be driven by anomalous subtropical wave breaking related to changes in the zero-wind line position with the QBO phase

A New System to Estimate and Reduce Electrical Energy Consumption of Domestic Hot Water in Spain

Energy consumption rose about 28% over the 2001 to 2011 period in the Spanish residential sector. In this environment, domestic hot water (DHW) represents the second highest energy demand. There are several methodologies to estimate DHW consumption, but each methodology uses different inputs and some of them are based on obsolete data. DHW energy consumption estimation is a key tool to plan modifications that could enhance this consumption and we decided to update the methodologies. We studied DHW consumption with data from 10 apartments in the same building during 18 months. As a result of the study, we updated one chosen methodology, adapting it to the current situation. One of the challenges to improve efficiency of DHW use is that most of people are not aware of how it is consumed in their homes. To help this information to reach consumers, we developed a website to allow users to estimate the final electrical energy needed for DHW. The site uses three estimation methodologies and chooses the best fit based on information given by the users. Finally, the application provides users with recommendations and tips to reduce their DHW consumption while still maintaining the desired comfort level

A New System for Households in Spain to Evaluate and Reduce Their Water Consumption

The objective of this paper is to describe a developed model and its corresponding application, known as System to Evaluate the Water Consumption at Home (SEWAT). The aim is to create a new model to evaluate the efficiency of water consumption. Thanks to the input of the water bills by users, the model allows them to check if water consumption is efficient, in order to give them an opportunity to evaluate their water usage. To succeed in it, several researches were tracked in order to establish consumer trends and to identify the most efficient value for this magnitude. Furthermore, a survey was conducted to obtain updated values to validate information from previous studies. However, the main aim of this model is to use the resources efficiently, so it has to be useful accordingly. Therefore, after the evaluation, the application has a section with recommendations for the users to reduce their water consumption through a range of different indications. This section is divided into four: bathroom, kitchen, new appliance and reusing water. Each section shows the expected benefits if the users follow the recommended options. The main result is a unique application in Spain, which includes a system of evaluation, comparison and a section of recommendations for the users. Eventually, the model will have a promising outcome, because it surely will change the awareness of citizens about this subject

A Study to Improve the Quality of Street Lighting in Spain

Street lighting has a big impact on the energy consumption of Spanish municipalities. To decrease this consumption, the Spanish government has developed two different regulations to improve energy savings and efficiency, and consequently, reduce greenhouse-effect gas emissions. However, after these efforts, they have not obtained the expected results. To improve the effectiveness of these regulations and therefore to optimize energy consumption, a study has been done to analyze the different devices which influence energy consumption with the intention of better understanding their behavior and performance. The devices analyzed were lamps, ballasts, street lamp globes, control systems and dimmable lighting systems. To improve their performance, they have been analyzed from three points of view: changes in technology, use patterns and standards. Thanks to this study, some aspects have been found that could be taken into account if we really wanted to use energy efficiently

Regulation of catalase–peroxidase (KatG) expression, isoniazid sensitivity and virulence by furA of Mycobacterium tuberculosis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74159/1/j.1365-2958.2001.02427.x.pd