Glutamine synthetase sequence evolution in the mycobacteria and their use as molecular markers for Actinobacteria speciation

<p>Abstract</p> <p>Background</p> <p>Although the gene encoding for glutamine synthetase (<it>gln</it>A) is essential in several organisms, multiple glnA copies have been identified in bacterial genomes such as those of the phylum <it>Actinobacteria</it>, notably the mycobacterial species. Intriguingly, previous reports have shown that only one copy (<it>gln</it>A1) is essential for growth in <it>M. tuberculosis</it>, while the other copies (<it>gln</it>A2, <it>gln</it>A3 and <it>gln</it>A4) are not.</p> <p>Results</p> <p>In this report it is shown that the <it>gln</it>A1 and <it>gln</it>A2 encoded glutamine synthetase sequences were inherited from an <it>Actinobacteria </it>ancestor, while the <it>gln</it>A4 and <it>gln</it>A3 encoded GS sequences were sequentially acquired during <it>Actinobacteria </it>speciation. The glutamine synthetase sequences encoded by <it>gln</it>A4 and <it>gln</it>A3 are undergoing reductive evolution in the mycobacteria, whilst those encoded by <it>gln</it>A1 and <it>gln</it>A2 are more conserved.</p> <p>Conclusion</p> <p>Different selective pressures by the ecological niche that the organisms occupy may influence the sequence evolution of <it>gln</it>A1 and <it>gln</it>A2 and thereby affecting phylogenies based on the protein sequences they encode. The findings in this report may impact the use of similar sequences as molecular markers, as well as shed some light on the evolution of glutamine synthetase in the mycobacteria.</p

Glutamate dehydrogenase and glutamine synthetase are regulated in response to nitrogen availability in Myocbacterium smegmatis

<p>Abstract</p> <p>Background</p> <p>The assimilation of nitrogen is an essential process in all prokaryotes, yet a relatively limited amount of information is available on nitrogen metabolism in the mycobacteria. The physiological role and pathogenic properties of glutamine synthetase (GS) have been extensively investigated in <it>Mycobacterium tuberculosis</it>. However, little is known about this enzyme in other mycobacterial species, or the role of an additional nitrogen assimilatory pathway via glutamate dehydrogenase (GDH), in the mycobacteria as a whole. We investigated specific enzyme activity and transcription of GS and as well as both possible isoforms of GDH (NAD⁺- and NADP⁺-specific GDH) under varying conditions of nitrogen availability in <it>Mycobacterium smegmatis </it>as a model for the mycobacteria.</p> <p>Results</p> <p>It was found that the specific activity of the aminating NADP⁺-GDH reaction and the deaminating NAD⁺-GDH reaction did not change appreciably in response to nitrogen availability. However, GS activity as well as the deaminating NADP⁺-GDH and aminating NAD⁺-GDH reactions were indeed significantly altered in response to exogenous nitrogen concentrations. Transcription of genes encoding for GS and the GDH isoforms were also found to be regulated under our experimental conditions.</p> <p>Conclusions</p> <p>The physiological role and regulation of GS in <it>M. smegmatis </it>was similar to that which has been described for other mycobacteria, however, in our study the regulation of both NADP⁺- and NAD⁺-GDH specific activity in <it>M. smegmatis </it>appeared to be different to that of other Actinomycetales. It was found that NAD⁺-GDH played an important role in nitrogen assimilation rather than glutamate catabolism as was previously thought, and is it's activity appeared to be regulated in response to nitrogen availability. Transcription of the genes encoding for NAD⁺-GDH enzymes seem to be regulated in <it>M. smegmatis </it>under the conditions tested and may contribute to the changes in enzyme activity observed, however, our results indicate that an additional regulatory mechanism may be involved. NADP⁺-GDH seemed to be involved in nitrogen assimilation due to a constitutive aminating activity. The deaminating reaction, however was observed to change in response to varying ammonium concentrations which suggests that NADP⁺-GDH is also regulated in response to nitrogen availability. The regulation of NADP⁺-GDH activity was not reflected at the level of gene transcription thereby implicating post-transcriptional modification as a regulatory mechanism in response to nitrogen availability.</p

Soft sensor design for the optimisation of parallel debutaniser columns: an industrial case study

This work demonstrates a practical implementation of a soft sensor to estimate the C5 hydrocarbon impurity in the butane product of a liquid petroleum gas (LPG) recovery system. Such a sensor can then subsequently be used to optimise the process. The process has two parallel debutaniser columns that feed a common LPG recovery system. The optimisation objective is to minimise the Reid vapour pressure (RVP) of the two debutaniser bottoms’ products. This optimisation problem can be solved with a simple advanced control implementation. However, the ability of the controller to minimise the process variation and drive the process to the optimal point is directly influenced by the quality of the constraining process variable. In this case, the key controlled variable (CV) is the debutaniser overheads C5 mass fraction. The designed soft sensor for this CV uses the general distillation shortcut (GDS) method, and is shown to represent the distillation column operation well. This work presents a derivation of the GDS method, and formulates a new approach for the feedback biasing of the two parallel debutaniser soft sensors.https://www.journals.elsevier.com/ifac-papersonlinepm2021Electrical, Electronic and Computer Engineerin

Pressure buffering control to reduce pollution and improve flow stability in industrial gas headers

This paper describes various regulatory and advanced control schemes which can be applied to industrial gas headers. The intention is to exploit the buffering capacity for pollution control as well as improve flow stability for consumers. The control schemes are compared using a Monte Carlo simulation on a simulated case study and a sensitivity analysis is done to evaluate the impact of variations in the gas properties on the cost functions. A compensated linear model predictive controller (CLMPC) is implemented on a real industrial header and compared with standard proportional–integral (PI) control. It is found that gas emissions and consumer stability can be substantially improved by intelligently utilising the available pressure buffering capacity in industrial gas headers.http://www.elsevier.com/locate/conengprachj2022Electrical, Electronic and Computer Engineerin

Decentralised model predictive control for parallel unit operation optimisation

This paper describes the application of decentralised model predictive control (DMPC) to parallel unit operations. A decentralised approach may provide advantages in terms of maintenance, online time, and tuning complexity. Total flow control and linearisation, flow biasing and mass balance baselayer schemes are discussed as well as the DMPC structures. Finally, an industrial case study is presented where a DMPC approach is applied to steam header pressure control and steam generation optimisation.https://www.journals.elsevier.com/ifac-papersonlineam2022Electrical, Electronic and Computer Engineerin

Anti-mycobacterium tuberculosis activity of polyherbal medicines used for the treatment of tuberculosis in Eastern Cape, South Africa.

Background: The emergence of drug-resistant strains of Mycobacterium tuberculosis has become a global public health problem. Polyherbal medicines offer great hope for developing alternative drugs for the treatment of tuberculosis. Objective: To evaluate the anti-tubercular activity of polyherbal medicines used for the treatment of tuberculosis. Methods: The remedies were screened against Mycobacterium tuberculosis H37Rv using Middlebrook 7H9 media and MGIT BACTEC 960 system. They were liquid preparations from King Williams Town site A (KWTa), King Williams Town site B (KWTb), King Williams Town site C (KWTc), Hogsback first site (HBfs), Hogsback second site (HBss), Hogsback third site (HBts), East London (EL), Alice (AL) and Fort Beaufort (FB). Results: The susceptibility testing revealed that all the remedies contain anti-tubercular activity with KWTa, KWTb, KWTc, HBfs, HBts, AL and FB exhibiting more activity at a concentration below 25 \ub5l/ml. Furthermore, MIC values exhibited inhibitory activity with the most active remedies from KWTa, HBfs and HBts at 1.562 \ub5g/ml. However, isoniazid showed more inhibitory activity against M. tuberculosis at 0.05 \ub5g/ml when compare to the polyherbal remedies. Conclusion: This study has indicated that these remedies could be potential sources of new anti-mycobacterial agents against M. tuberculosis. However, the activity of these preparations and their active principles still require in vivo study in order to assess their future as new anti-tuberculosis agents

Gene activation during skeletal muscle development

Thesis (Ph.D.) -- University of Stellenbosch, 1986.One copy microfiche.Full text to be digitised and attached to bibliographic record

Chromatin changes during development of chicken muscle cells

Thesis (M.Sc.) - University of Stellenbosch, 1980.Full text to be digitised and attached to bibliographic record

The association of OASL and type I interferons in the pathogenesis and survival of intracellular replicating bacterial species

CITATION: Leisching, G., Wiid, I. & Baker, B. 2017. The association of OASL and type I interferons in the pathogenesis and survival of intracellular replicating bacterial species. Frontiers in Cellular and Infection Microbiology, 7:196, doi:10.3389/fcimb.2017.00196.The original publication is available at https://www.frontiersin.orgThe type I IFN response quickly became associated with its role in the innate immune response to viral infection. The past few years have seen the significance of IFNs expand in breadth to include non-viral pathogens. Previous work has identified that following viral infection, type I IFN signaling induces the production of the 2′-5′-oligoadenylate synthetase (OAS) family, which include OAS1, OAS2, OAS3, and OAS-like (OASL) protein. OASL was identified to be strongly induced following viral infection through engaging the RNA sensor RIG-I and increasing signaling through this pathway to enhance the anti-viral type I IFN response. Surprisingly, infection with viral dsDNA revealed an IFN inhibitory role and therefore pro-viral function of OASL through the inhibition of the cGAS cytosolic DNA sensing mechanism. Intracellular bacteria are able to activate the cytosolic DNA sensing pathway, however the role of OASL during bacterial infection is largely unknown. Vacuolar pathogenic microbes such as mycobacteria induce OASL early post infection, where it functions in a prosurvival fashion by inhibiting autophagic mechanisms and antimicrobial peptide expression. This suggests an underestimated role of OASL in the innate immune response to infection with a variety of pathogens and points to OASL-associated modulation of the type I IFN response. OASL may therefore play a critical role in defining the outcome of infection. We provide a brief update on the recent developments of the OAS family of proteins in response to DNA and RNA virus infections, as well as discuss evidence of Oasl expression in response to a number of cytosolic and vacuolar replicating bacterial pathogens.https://www.frontiersin.org/articles/10.3389/fcimb.2017.00196/fullPublisher's versio