scholarly journals Self-organization controls expression more than abundance of molecular components of transcription and translation in confined cell-free gene expression

2018 ◽  
Author(s):  
P.M. Caveney ◽  
R. Dabbs ◽  
G. Chauhan ◽  
S.E. Norred ◽  
C.P. Collier ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Production ◽  
Self Organization ◽  
Large Variability ◽  
Expression Noise ◽  
Expression Efficiency ◽  
Cell Extracts ◽  
Reaction Chambers ◽  
Free Gene ◽  
Molecular Components

AbstractCell-free gene expression using purified components or cell extracts has become an important platform for synthetic biology that is finding a growing numBer of practical applications. Unfortunately, at cell-relevant reactor volumes, cell-free expression suffers from excessive variability (noise) such that protein concentrations may vary by more than an order of magnitude across a population of identically constructed reaction chambers. Consensus opinion holds that variability in expression is due to the stochastic distribution of expression resources (DNA, RNAP, ribosomes, etc.) across the population of reaction chambers. In contrast, here we find that chamber-to-chamber variation in the expression efficiency generates the large variability in protein production. Through analysis and modeling, we show that chambers self-organize into expression centers that control expression efficiency. Chambers that organize into many centers, each having relatively few expression resources, exhibit high expression efficiency. Conversely, chambers that organize into just a few centers where each center has an abundance of resources, exhibit low expression efficiency. A particularly surprising finding is that diluting expression resources reduces the chamber-to-chamber variation in protein production. Chambers with dilute pools of expression resources exhibit higher expression efficiency and lower expression noise than those with more concentrated expression resources. In addition to demonstrating the means to tune expression noise, these results demonstrate that in cell-free systems, self-organization may exert even more influence over expression than the abundance of the molecular components of transcription and translation. These observations in cell-free platform may elucidate how self-organized, membrane-less structures emerge and function in cells.

scholarly journals Self-Organization Controls Expression More than Abundance of Molecular Components of Transcription and Translation in Confined Cell-Free Gene Expression

2018 ◽  
Author(s):  
Patrick M. Caveney ◽  
Rosemary M. Dabbs ◽  
Gaurav Chauhan ◽  
S. Elizabeth Norred ◽  
C. Patrick Collier ◽  
...  
Keyword(s):  
Gene Expression ◽  
Self Organization ◽  
Free Gene ◽  
Molecular Components

Probing Cell-Free Gene Expression Noise in Femtoliter Volumes

2013 ◽  
Vol 2 (9) ◽  
pp. 497-505 ◽  
Author(s):  
David K. Karig ◽  
Seung-Yong Jung ◽  
Bernadeta Srijanto ◽  
C. Patrick Collier ◽  
Michael L. Simpson
Keyword(s):  
Gene Expression ◽  
Gene Expression Noise ◽  
Expression Noise ◽  
Free Gene

scholarly journals Controlling Cell-Free Gene Expression Behavior by Tuning Membrane Transport Properties

2019 ◽  
Author(s):  
Patrick M. Caveney ◽  
Rosemary M. Dabbs ◽  
William T. McClintic ◽  
S. Elizabeth Norred ◽  
C. Patrick Collier ◽  
...  
Keyword(s):  
Gene Expression ◽  
Membrane Permeability ◽  
Treatment Method ◽  
Lipid Vesicle ◽  
Molecular Signaling ◽  
Expression Variability ◽  
Reaction Chambers ◽  
Free Gene ◽  
Optical Treatment ◽  
Membrane Engineering

SummaryControlled transport of molecules across boundaries for energy exchange, sensing, and communication is an essential step toward cell-like synthetic systems. This communication between the gene expression compartment and the external environment requires reaction chambers that are permeable to molecular species that influence expression. In lipid vesicle reaction chambers, species that support expression – from small ions to amino acids – may diffuse across membranes and amplify protein production. However, vesicle-to-vesicle variation in membrane permeability may lead to low total expression and high variability in this expression. We demonstrate a simple optical treatment method that greatly reduces the variability in membrane permeability. When transport across the membrane was essential for expression, this optical treatment increased mean expression level by ~6-fold and reduced expression variability by nearly two orders of magnitude. These results demonstrate membrane engineering may enable essential steps toward cell-like synthetic systems. The experimental platform described here provides a means of understanding controlled transport motifs in individual cells and groups of cells working cooperatively through cell-to-cell molecular signaling.

scholarly journals In silico Design of Linear DNA for Robust Cell-Free Gene Expression

2021 ◽  
Vol 9 ◽  
Author(s):  
Xinjie Chen ◽  
Yuan Lu
Keyword(s):  
Gene Expression ◽  
Protein Expression ◽  
High Throughput Screening ◽  
Expression System ◽  
Dna Templates ◽  
Linear Dna ◽  
Low Protein ◽  
Cell Extracts ◽  
Free Gene ◽  
Expression Templates

Cell-free gene expression systems with linear DNA expression templates (LDETs) have been widely applied in artificial cells, biochips, and high-throughput screening. However, due to the degradation caused by native nucleases in cell extracts, the transcription with linear DNA templates is weak, thereby resulting in low protein expression level, which greatly limits the development of cell-free systems using linear DNA templates. In this study, the protective sequences for stabilizing linear DNA and the transcribed mRNAs were rationally designed according to nucleases’ action mechanism, whose effectiveness was evaluated through computer simulation and cell-free gene expression. The cell-free experiment results indicated that, with the combined protection of designed sequence and GamS protein, the protein expression of LDET-based cell-free systems could reach the same level as plasmid-based cell-free systems. This study would potentially promote the development of the LDET-based cell-free gene expression system for broader applications.

scholarly journals Improving cell-free glycoprotein synthesis by characterizing and enriching native membrane vesicles

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jasmine M. Hershewe ◽  
Katherine F. Warfel ◽  
Shaelyn M. Iyer ◽  
Justin A. Peruzzi ◽  
Claretta J. Sullivan ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Synthetic Biology ◽  
Membrane Protein ◽  
Membrane Vesicles ◽  
Processing Methods ◽  
Glycoprotein Synthesis ◽  
On Demand ◽  
Free Gene ◽  
Membrane Bound

AbstractCell-free gene expression (CFE) systems from crude cellular extracts have attracted much attention for biomanufacturing and synthetic biology. However, activating membrane-dependent functionality of cell-derived vesicles in bacterial CFE systems has been limited. Here, we address this limitation by characterizing native membrane vesicles in Escherichia coli-based CFE extracts and describing methods to enrich vesicles with heterologous, membrane-bound machinery. As a model, we focus on bacterial glycoengineering. We first use multiple, orthogonal techniques to characterize vesicles and show how extract processing methods can be used to increase concentrations of membrane vesicles in CFE systems. Then, we show that extracts enriched in vesicle number also display enhanced concentrations of heterologous membrane protein cargo. Finally, we apply our methods to enrich membrane-bound oligosaccharyltransferases and lipid-linked oligosaccharides for improving cell-free N-linked and O-linked glycoprotein synthesis. We anticipate that these methods will facilitate on-demand glycoprotein production and enable new CFE systems with membrane-associated activities.

Gastrin regulates growth of human pancreatic cancer in a tonic and autocrine fashion

1996 ◽  
Vol 270 (5) ◽  
pp. R1078-R1084 ◽  
Author(s):  
J. P. Smith ◽  
A. Shih ◽  
Y. Wu ◽  
P. J. McLaughlin ◽  
I. S. Zagon
Keyword(s):  
Gene Expression ◽  
Pancreatic Cancer ◽  
Cell Lines ◽  
Cancer Cell ◽  
Pancreatic Cancer Cell ◽  
Cancer Cell Lines ◽  
Human Pancreatic Cancer ◽  
Growth Media ◽  
Human Pancreatic Cancer Cell ◽  
Cell Extracts

The gastrointestinal peptides gastrin and cholecystokinin (CCK) stimulate growth of human pancreatic cancer through a CCK-B/gastrin- like receptor. In the present study we evaluated whether growth of human pancreatic cancer is endogenously regulated by gastrin. Immunohistomical examination of BxPC-3 cells and tumor xenografts revealed specifc gastrin immunoreactivity. Gastrin was detected by radioimmunoassay in pancreatic cancer cell extracts and in pancreatic cancer cell extracts and in the growth media. With use of reverse-transcriptase polymerase chain reaction gastrin gene expression was detected in both cultured BxPC-3 cancer cells and transplanted tumors, as well as seven addition human pancreatic cancer cell lines. Growth of BxPC-3 human pancreatic cancer cell in serum-free medium was inhibited by the addition of the CCK-B/gastrin receptor antagonist L-365,260, and gastrin treatment reversed the inhibitory effect of the antagonist. A selective gastrin antibody (Ab repressed growth of BxPC-3 cells. Gastrin immunoreactivity was detected in fresh human pancreatic cancer specimens but not in normal human pancreatic tissue. These data provide the first evidence that growth of a human pancreatic cancer is tonically stimulated by the autocrine production of gastrin. Evidence for the ubiquity of this system was provided by the detection of gastrin gene expression in multiple human pancreatic cancer cell lines and detection of gastrin in cell lines and fresh pancreatic tumors.

Reduction in gene expression noise by targeted increase in accessibility at gene loci

2021 ◽  
Vol 118 (42) ◽  
pp. e2018640118
Author(s):  
LaTasha C. R. Fraser ◽  
Ryan J. Dikdan ◽  
Supravat Dey ◽  
Abhyudai Singh ◽  
Sanjay Tyagi
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Single Molecule ◽  
Single Cells ◽  
Global Changes ◽  
Messenger Rnas ◽  
Histone Acetyl Transferase ◽  
Gene Expression Noise ◽  
Expression Noise ◽  
Eukaryotic Genes

Many eukaryotic genes are expressed in randomly initiated bursts that are punctuated by periods of quiescence. Here, we show that the intermittent access of the promoters to transcription factors through relatively impervious chromatin contributes to this “noisy” transcription. We tethered a nuclease-deficient Cas9 fused to a histone acetyl transferase at the promoters of two endogenous genes in HeLa cells. An assay for transposase-accessible chromatin using sequencing showed that the activity of the histone acetyl transferase altered the chromatin architecture locally without introducing global changes in the nucleus and rendered the targeted promoters constitutively accessible. We measured the gene expression variability from the gene loci by performing single-molecule fluorescence in situ hybridization against mature messenger RNAs (mRNAs) and by imaging nascent mRNA molecules present at active gene loci in single cells. Because of the increased accessibility of the promoter to transcription factors, the transcription from two genes became less noisy, even when the average levels of expression did not change. In addition to providing evidence for chromatin accessibility as a determinant of the noise in gene expression, our study offers a mechanism for controlling gene expression noise which is otherwise unavoidable.

Sign in / Sign up

Export Citation Format

Share Document