Transcription in cyanobacteria: a distinctive machinery and putative mechanisms

2019 ◽  
Vol 47 (2) ◽  
pp. 679-689 ◽  
Author(s):  
Amber Riaz-Bradley
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Circadian Rhythm ◽  
Bacterial Species ◽  
Rna Cleavage ◽  
Termination Factor ◽  
Trigger Loop ◽  
Genome Damage ◽  
Loop Element ◽  
Rna Transcript

Abstract Transcription in cyanobacteria involves several fascinating features. Cyanobacteria comprise one of the very few groups in which no proofreading factors (Gre homologues) have been identified. Gre factors increase the efficiency of RNA cleavage, therefore helping to maintain the fidelity of the RNA transcript and assist in the resolution of stalled RNAPs to prevent genome damage. The vast majority of bacterial species encode at least one of these highly conserved factors and so their absence in cyanobacteria is intriguing. Additionally, the largest subunit of bacterial RNAP has undergone a split in cyanobacteria to form two subunits and the SI3 insertion within the integral trigger loop element is roughly 3.5 times larger than in Escherichia coli. The Rho termination factor also appears to be absent, leaving cyanobacteria to rely solely on an intrinsic termination mechanism. Furthermore, cyanobacteria must be able to respond to environment signals such as light intensity and tightly synchronise gene expression and other cell activities to a circadian rhythm.

Involvement of the cgtA gene function in stimulation of DNA repair in Escherichia coli and Vibrio harveyi

Microbiology ◽  
2003 ◽  
Vol 149 (7) ◽  
pp. 1763-1770 ◽  
Author(s):  
Ryszard Zielke ◽  
Aleksandra Sikora ◽  
Rafał Dutkiewicz ◽  
Grzegorz Wegrzyn ◽  
Agata Czyż
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Dna Repair ◽  
Gene Product ◽  
Uv Irradiation ◽  
Vibrio Harveyi ◽  
Bacterial Species ◽  
Wild Type ◽  
E Coli ◽  
Stimulation Of

CgtA is a member of the Obg/Gtp1 subfamily of small GTP-binding proteins. CgtA homologues have been found in various prokaryotic and eukaryotic organisms, ranging from bacteria to humans. Nevertheless, despite the fact that cgtA is an essential gene in most bacterial species, its function in the regulation of cellular processes is largely unknown. Here it has been demonstrated that in two bacterial species, Escherichia coli and Vibrio harveyi, the cgtA gene product enhances survival of cells after UV irradiation. Expression of the cgtA gene was found to be enhanced after UV irradiation of both E. coli and V. harveyi. Moderate overexpression of cgtA resulted in higher UV resistance of E. coli wild-type and dnaQ strains, but not in uvrA, uvrB, umuC and recA mutant hosts. Overexpression of the E. coli recA gene in the V. harveyi cgtA mutant, which is very sensitive to UV light, restored the level of survival of UV-irradiated cells to the levels observed for wild-type bacteria. Moreover, the basal level of the RecA protein was lower in a temperature-sensitive cgtA mutant of E. coli than in the cgtA + strain, and contrary to wild-type bacteria, no significant increase in recA gene expression was observed after UV irradiation of this cgtA mutant. Finally, stimulation of uvrB gene transcription under these conditions was impaired in the V. harveyi cgtA mutant. All these results strongly suggest that the cgtA gene product is involved in DNA repair processes, most probably by stimulation of recA gene expression and resultant activation of RecA-dependent DNA repair pathways.

scholarly journals Aminoglycosides induce a bacterial senescent state that increases antibiotic tolerance in treatment-naïve cells

2021 ◽  
Author(s):  
Christian T. Meyer ◽  
Giancarlo N. Bruni ◽  
Ben Dodd ◽  
Joel M. Kralj
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Bacterial Species ◽  
Genetic Resistance ◽  
Membrane Integrity ◽  
Antibiotic Tolerance ◽  
Paracrine Signaling ◽  
E Coli ◽  
Evolutionary Innovation ◽  
Treatment Naïve

Bacterial evolution of antibiotic resistance is facilitated by non-genetic resistance that increases drug tolerance, buying time for evolutionary innovation. Escherichia coli treated with aminoglycosides permanently lose the ability to divide within four hours, yet we discovered a majority of cells maintain membrane integrity and metabolic activity greater than two days post treatment — a bacterial senescent-like state. These cells, which we term zombies, exhibit dynamic gene expression and metabolomic profiles, even after irreversible exit from the cell cycle. Our data reveal zombies upregulate the phage shock protein pathway to maintain membrane integrity. Remarkably, though unable to form new colonies, zombies increase the antibiotic tolerance of treatment-naïve cells, implying chemical communication. Chemical supplementation and genetic knockouts show that zombies communicate with treatment-naïve cells by secreting indole. In summary, our study revealed a bacterial senescent-like state, induced by aminoglycosides, that decreases the antibiotic susceptibility of multiple bacterial species. Thus, E. coli zombies utilize paracrine signaling to promote non-genetic antibiotic tolerance.

Gene Expression Differences in White Blood Cells after Escherichia coli Infection in Chickens

2012 ◽  
Author(s):  
Erin Sandford ◽  
Megan Orr ◽  
Xianyao Li ◽  
Huaijun Zhou ◽  
timothy J. Johnson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Blood Cells ◽  
White Blood Cells ◽  
Escherichia Coli Infection
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