CRISPR-assisted multi-dimensional regulation for fine-tuning gene expression in Bacillus subtilis

AbstractBacterial quorum sensing (QS) is based on signal molecules (SM), which increase in concentration with cell density. At critical SM concentration, a variety of adaptive genes sharply change their expression from basic level to maximum level. In general, this sharp transition, a hallmark of true QS, requires an SM dependent positive feedback loop, where SM enhances its own production. Some communication systems, like the peptide SM-based ComQXPA communication system of Bacillus subtilis, do not have this feedback loop and we do not understand how and if the sharp transition in gene expression is achieved. Based on experiments and mathematical modeling, we observed that the SM peptide ComX encodes the information about cell density, specific cell growth rate, and even oxygen concentration, which ensure power-law increase in SM production. This enables together with the cooperative response to SM (ComX) a sharp transition in gene expression level and this without the SM dependent feedback loop. Due to its ultra-sensitive nature, the ComQXPA can operate at SM concentrations that are 100–1000 times lower than typically found in other QS systems, thereby substantially reducing the total metabolic cost of otherwise expensive ComX peptide.

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Competing Endogenous RNAs in Cervical Carcinogenesis: A New Layer of Complexity

Processes ◽

10.3390/pr9060991 ◽

2021 ◽

Vol 9 (6) ◽

pp. 991

Author(s):

Fernanda Costa Brandão Berti ◽

Sara Cristina Lobo-Alves ◽

Camila de Freitas Oliveira-Toré ◽

Amanda Salviano-Silva ◽

Karen Brajão de Oliveira ◽

...

Keyword(s):

Gene Expression ◽

Fine Tuning ◽

Molecular Networks ◽

Cervical Carcinogenesis ◽

Molecular Changes ◽

Cellular Processes ◽

Target Mrnas ◽

Competing Endogenous Rnas ◽

Cervical Cells ◽

Post Transcriptional Regulation

MicroRNAs (miRNAs) regulate gene expression by binding to complementary sequences within target mRNAs. Apart from working ‘solo’, miRNAs may interact in important molecular networks such as competing endogenous RNA (ceRNA) axes. By competing for a limited pool of miRNAs, transcripts such as long noncoding RNAs (lncRNAs) and mRNAs can regulate each other, fine-tuning gene expression. Several ceRNA networks led by different lncRNAs—described here as lncRNA-mediated ceRNAs—seem to play essential roles in cervical cancer (CC). By conducting an extensive search, we summarized networks involved in CC, highlighting the major impacts of such dynamic molecular changes over multiple cellular processes. Through the sponging of distinct miRNAs, some lncRNAs as HOTAIR, MALAT1, NEAT1, OIP5-AS1, and XIST trigger crucial molecular changes, ultimately increasing cell proliferation, migration, invasion, and inhibiting apoptosis. Likewise, several lncRNAs seem to be a sponge for important tumor-suppressive miRNAs (as miR-140-5p, miR-143-3p, miR-148a-3p, and miR-206), impairing such molecules from exerting a negative post-transcriptional regulation over target mRNAs. Curiously, some of the involved mRNAs code for important proteins such as PTEN, ROCK1, and MAPK1, known to modulate cell growth, proliferation, apoptosis, and adhesion in CC. Overall, we highlight important lncRNA-mediated functional interactions occurring in cervical cells and their closely related impact on cervical carcinogenesis.

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Interaction of 7SK with the Smn complex modulates snRNP production

Nature Communications ◽

10.1038/s41467-021-21529-1 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Changhe Ji ◽

Jakob Bader ◽

Pradhipa Ramanathan ◽

Luisa Hennlein ◽

Felix Meissner ◽

...

Keyword(s):

Gene Expression ◽

Transcriptional Regulation ◽

Fine Tuning ◽

Global Changes ◽

Functional Association ◽

Transcriptional Inhibition ◽

Smn Complex ◽

Core Components

AbstractGene expression requires tight coordination of the molecular machineries that mediate transcription and splicing. While the interplay between transcription kinetics and spliceosome fidelity has been investigated before, less is known about mechanisms regulating the assembly of the spliceosomal machinery in response to transcription changes. Here, we report an association of the Smn complex, which mediates spliceosomal snRNP biogenesis, with the 7SK complex involved in transcriptional regulation. We found that Smn interacts with the 7SK core components Larp7 and Mepce and specifically associates with 7SK subcomplexes containing hnRNP R. The association between Smn and 7SK complexes is enhanced upon transcriptional inhibition leading to reduced production of snRNPs. Taken together, our findings reveal a functional association of Smn and 7SK complexes that is governed by global changes in transcription. Thus, in addition to its canonical nuclear role in transcriptional regulation, 7SK has cytosolic functions in fine-tuning spliceosome production according to transcriptional demand.

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Analysis by fluorescence microscopy of the development of compartment-specific gene expression during sporulation of Bacillus subtilis.

Journal of Bacteriology ◽

10.1128/jb.176.10.2898-2905.1994 ◽

1994 ◽

Vol 176 (10) ◽

pp. 2898-2905 ◽

Cited By ~ 10

Author(s):

J E Bylund ◽

L Zhang ◽

M A Haines ◽

M L Higgins ◽

P J Piggot

Keyword(s):

Gene Expression ◽

Bacillus Subtilis ◽

Fluorescence Microscopy ◽

Specific Gene ◽

Specific Gene Expression

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Refactoring of a synthetic raspberry ketone pathway with EcoFlex

Microbial Cell Factories ◽

10.1186/s12934-021-01604-4 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Simon J. Moore ◽

Yonek B. Hleba ◽

Sarah Bischoff ◽

David Bell ◽

Karen M. Polizzi ◽

...

Keyword(s):

Gene Expression ◽

Synthetic Biology ◽

Combinatorial Libraries ◽

Value Added ◽

Microtiter Plate ◽

Fine Tuning ◽

Golden Gate ◽

E Coli ◽

Fine Chemical ◽

Raspberry Ketone

Abstract Background A key focus of synthetic biology is to develop microbial or cell-free based biobased routes to value-added chemicals such as fragrances. Originally, we developed the EcoFlex system, a Golden Gate toolkit, to study genes/pathways flexibly using Escherichia coli heterologous expression. In this current work, we sought to use EcoFlex to optimise a synthetic raspberry ketone biosynthetic pathway. Raspberry ketone is a high-value (~ £20,000 kg−1) fine chemical farmed from raspberry (Rubeus rubrum) fruit. Results By applying a synthetic biology led design-build-test-learn cycle approach, we refactor the raspberry ketone pathway from a low level of productivity (0.2 mg/L), to achieve a 65-fold (12.9 mg/L) improvement in production. We perform this optimisation at the prototype level (using microtiter plate cultures) with E. coli DH10β, as a routine cloning host. The use of E. coli DH10β facilitates the Golden Gate cloning process for the screening of combinatorial libraries. In addition, we also newly establish a novel colour-based phenotypic screen to identify productive clones quickly from solid/liquid culture. Conclusions Our findings provide a stable raspberry ketone pathway that relies upon a natural feedstock (L-tyrosine) and uses only constitutive promoters to control gene expression. In conclusion we demonstrate the capability of EcoFlex for fine-tuning a model fine chemical pathway and provide a range of newly characterised promoter tools gene expression in E. coli.

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