scholarly journals Transcription-coupled DNA supercoiling dictates the chromosomal arrangement of bacterial genes

2016 ◽  
Vol 44 (4) ◽  
pp. 1514-1524 ◽  
Author(s):  
Patrick Sobetzko
Keyword(s):  
Dna Supercoiling ◽  
Chromosomal Arrangement ◽  
Bacterial Genes

scholarly journals Co-operative roles for DNA supercoiling and nucleoid-associated proteins in the regulation of bacterial transcription

2013 ◽  
Vol 41 (2) ◽  
pp. 542-547 ◽  
Author(s):  
Charles J. Dorman
Keyword(s):  
Regulatory Protein ◽  
Dna Supercoiling ◽  
Complex Nature ◽  
Regulation Of Transcription ◽  
Transcription Control ◽  
Dna Relaxation ◽  
Bacterial Transcription ◽  
Associated Proteins ◽  
Topological State ◽  
Bacterial Genes

DNA supercoiling and NAPs (nucleoid-associated proteins) contribute to the regulation of transcription of many bacterial genes. The horizontally acquired SPI (Salmonella pathogenicity island) genes respond positively to DNA relaxation, they are activated and repressed by the Fis (factor for inversion stimulation) and H-NS (histone-like nucleoid-structuring) NAPs respectively, and are positively controlled by the OmpR global regulatory protein. The ompR gene is autoregulated and responds positively to DNA relaxation. Binding of the Fis and OmpR proteins to their targets in DNA is differentially sensitive to its topological state, whereas H-NS binds regardless of the topological state of the DNA. These data illustrate the overlapping and complex nature of NAP and DNA topological contributions to transcription control in bacteria.

The gut microbiota resistome provides development of drug resistance in causative agents of human infectious diseases

2017 ◽  
pp. 20-32 ◽  
Author(s):  
Е.Н. Ильина ◽  
Е.И. Олехнович ◽  
А.В. Павленко
Keyword(s):  
Drug Resistance ◽  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Integrated Approach ◽  
Modern Medicine ◽  
Pathogenic Microorganisms ◽  
Human Pathogens ◽  
Potential Source ◽  
Causative Agents ◽  
Bacterial Genes

С течением времени подходы к изучению резистентности к антибиотикам трансформировались от сосредоточения на выделенных в виде чистой культуры патогенных микроорганизмах к исследованию резистентности на уровне микробных сообществ, составляющих биотопы человека и окружающей среды. По мере того, как продвигается изучение устойчивости к антибиотикам, возникает необходимость использования комплексного подхода для улучшения информирования мирового сообщества о наблюдаемых тенденциях в этой области. Все более очевидным становится то, что, хотя не все гены резистентности могут географически и филогенетически распространяться, угроза, которую они представляют, действительно серьезная и требует комплексных междисциплинарных исследований. В настоящее время резистентность к антибиотикам среди патогенов человека стала основной угрозой в современной медицине, и существует значительный интерес к определению ниши, в которых бактерии могут получить гены антибиотикорезистентности, и механизмов их передачи. В данном обзоре мы рассматриваем проблемы, возникшие на фоне широкого использования человечеством антибактериальных препаратов, в свете формирования микрофлорой кишечника резервуара генов резистентности. Over the time, studies of antibiotic resistance have transformed from focusing on pathogenic microorganisms isolated as a pure culture to analysis of resistance at the level of microbial communities that constitute human and environmental biotopes. Advancing studies of antibiotic resistance require an integrated approach to enhance availability of information about observed tendencies in this field to the global community. It becomes increasingly obvious that, even though not all resistance genes can geographically and phylogenetically spread, the threat they pose is indeed serious and requires complex interdisciplinary research. Currently, the antibiotic resistance of human pathogens has become a challenge to modern medicine, which is now focusing on determining a potential source for bacterial genes of drug resistance and mechanisms for the gene transmission. In this review, we discussed problems generated by the widespread use of antibacterial drugs in the light of forming a reservoir of resistance genes by gut microflora.

scholarly journals Interactions of the Streptococcus pneumoniae Toxin-Antitoxin RelBE Proteins with Their Target DNA

2021 ◽  
Vol 9 (4) ◽  
pp. 851
Author(s):  
Inmaculada Moreno-Córdoba ◽  
Wai-Ting Chan ◽  
Concha Nieto ◽  
Manuel Espinosa
Keyword(s):  
Streptococcus Pneumoniae ◽  
Self Regulation ◽  
Mrna Translation ◽  
Dna Supercoiling ◽  
Bacterial Toxin ◽  
Type Ii ◽  
Cellular Functions ◽  
Dna Backbone ◽  
Different Strains ◽  
Palindromic Sequences

Type II bacterial toxin-antitoxin (TA) systems are found in most bacteria, archaea, and mobile genetic elements. TAs are usually found as a bi-cistronic operon composed of an unstable antitoxin and a stable toxin that targets crucial cellular functions like DNA supercoiling, cell-wall synthesis or mRNA translation. The type II RelBE system encoded by the pathogen Streptococcus pneumoniae is highly conserved among different strains and participates in biofilm formation and response to oxidative stress. Here, we have analyzed the participation of the RelB antitoxin and the RelB:RelE protein complex in the self-regulation of the pneumococcal relBE operon. RelB acted as a weak repressor, whereas RelE performed the role of a co-repressor. By DNA footprinting experiments, we show that the proteins bind to a region that encompasses two palindromic sequences that are located around the −10 sequences of the single promoter that directs the synthesis of the relBE mRNA. High-resolution footprinting assays showed the distribution of bases whose deoxyriboses are protected by the bound proteins, demonstrating that RelB and RelB:RelE contacted the DNA backbone on one face of the DNA helix and that these interactions extended beyond the palindromic sequences. Our findings suggest that the binding of the RelBE proteins to its DNA target would lead to direct inhibition of the binding of the host RNA polymerase to the relBE promoter.

scholarly journals Mode of action and substrate specificities of cellulases from cloned bacterial genes.

1984 ◽  
Vol 259 (16) ◽  
pp. 10455-10459
Author(s):  
N R Gilkes ◽  
M L Langsford ◽  
D G Kilburn ◽  
R C Miller ◽  
R A Warren
Keyword(s):  
Mode Of Action ◽  
Substrate Specificities ◽  
Bacterial Genes

scholarly journals Chironomus ramosus Larval Microbiome Composition Provides Evidence for the Presence of Detoxifying Enzymes

2021 ◽  
Vol 9 (8) ◽  
pp. 1571
Author(s):  
Rotem Sela ◽  
Sivan Laviad-Shitrit ◽  
Leena Thorat ◽  
Bimalendu B. Nath ◽  
Malka Halpern
Keyword(s):  
Aquatic Insects ◽  
Bacterial Community Composition ◽  
Laboratory Culture ◽  
Metagenomic Analysis ◽  
Sequence Variants ◽  
Microbiota Composition ◽  
Detoxifying Enzymes ◽  
Toxic Compounds ◽  
Microbiome Composition ◽  
Bacterial Genes

Chironomids (Diptera; Chironomidae) are aquatic insects that are abundant in freshwater. We aimed to study the endogenous microbiota composition of Chironomus ramosus larvae that were sampled from the Mutha River and a laboratory culture in India. Furthermore, we performed a metagenomic analysis of the larval microbiome, sampled from the Mutha River. Significant differences were found between the bacterial community composition of C. ramosus larvae that were sampled from the Mutha River and the laboratory culture. A total of 54.7% of the amplicon sequence variants (ASVs) that were identified in the larvae from the Mutha River were unique, compared to only 12.9% of unique ASVs that were identified from the laboratory-reared larvae. The four most abundant phyla across all samples were: Proteobacteria, Fusobacteria, Firmicutes, and Bacteroidetes, while the nine most abundant genera were: Aeromonas, Alkanindiges, Breznakia, Cetobacterium, Chryseobacterium, Desulfovibrio, Dysgonomonas, Thiothrix, and Vibrio. Moreover, in the metagenomic analysis, we detected bacterial genes and bacterial pathways that demonstrated the ability to degrade different toxic compounds, detoxify metal, and confer resistance to antibiotics and UV radiation, amongst other functions. The results illuminate the fact that there are detoxifying enzymes in the C. ramosus larval microbiome that possibly play a role in protecting the insect in polluted environments.

Bacterial DNA supercoiling and

1991 ◽  
Vol 219 (3) ◽  
pp. 443-450 ◽  
Author(s):  
Li-Shan Hsieh ◽  
Richard M. Burger ◽  
Karl Drlica
Keyword(s):  
Dna Supercoiling ◽  
Bacterial Dna

scholarly journals Endogenous Fluctuations of DNA Topology in the Chloroplast of Chlamydomonas reinhardtii

1998 ◽  
Vol 18 (12) ◽  
pp. 7235-7242 ◽  
Author(s):  
Maria L. Salvador ◽  
Uwe Klein ◽  
Lawrence Bogorad
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Chloroplast Genome ◽  
Continuous Light ◽  
Dna Supercoiling ◽  
Dna Topology ◽  
Chloroplast Gene ◽  
Chloroplast Gene Expression ◽  
Endogenous Fluctuations ◽  
Unicellular Green Alga ◽  
In Cells

ABSTRACT DNA supercoiling in the chloroplast of the unicellular green algaChlamydomonas reinhardtii was found to change with a diurnal rhythm in cells growing in alternating 12-h dark–12-h light periods. Highest and lowest DNA superhelicities occurred at the beginning and towards the end of the 12-h light periods, respectively. The fluctuations in DNA supercoiling occurred concurrently and in the same direction in two separate parts of the chloroplast genome, one containing the genes psaB, rbcL, andatpA and the other containing the atpB gene. Fluctuations were not confined to transcribed DNA regions, indicating simultaneous changes in DNA conformation all over the chloroplast genome. Because the diurnal fluctuations persisted in cells kept in continuous light, DNA supercoiling is judged to be under endogenous control. The endogenous fluctuations in chloroplast DNA topology correlated tightly with the endogenous fluctuations of overall chloroplast gene transcription and with those of the pool sizes of most chloroplast transcripts analyzed. This result suggests that DNA superhelical changes have a role in the regulation of chloroplast gene expression in Chlamydomonas.

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