Read by QxMD icon Read

Lac operon

Atul Narang, Stefan Oehler
The lac (lactose) operon (processes β-galactosides) and the mel (melibiose) operon (processes α-galactosides) of Escherichia coli have a close historical connection. A number of shared substrates and effectors of the permeases and regulatory proteins has been reported over the years. Up to now, β-thiogalactosides like TMG (methyl-β-D-thiogalactopyranoside) and IPTG (isopropyl-β-D-thiogalactopyranoside) are generally not considered inducers of the mel operon. The same is true for β-galactosides like lactose (β-D-galactopyranosyl-(1→4)-D-glucose), which is a substrate, but itself not an inducer of the lac operon...
February 13, 2017: Journal of Bacteriology
Fangfei Li, Yang Tang
Boolean networks serve a powerful tool in analysis of genetic regulatory networks since it emphasizes the fundamental principles and establishes a nature framework for capturing the dynamics of regulation of cellular states. In this paper, the robust reachability of Boolean control networks is investigated by means of semi-tensor product. Necessary and sufficient conditions for the robust reachability of Boolean control networks are provided, in which control inputs relying on disturbances or not are considered, respectively...
April 20, 2016: IEEE/ACM Transactions on Computational Biology and Bioinformatics
Sheng Wang, Mei-Nan Zhang, Na-Ling Bai, Hai-Tao Ding, Xu-Fen Zhu, Yu-Hua Zhao
Cupriavidus basilensis is a species with diverse metabolic capabilities, including degradation of xenobiotics and heavy metal resistance. Although the genomes of several strains of this species have been sequenced, no plasmid has yet been constructed for genetic engineering in this species. In this study, we identified a novel plasmid, designated pWS, from C. basilensis WS with a copy number of 1-3 per cell and a length of 2150 bp. pWS contained three protein-coding genes, among which only rep was required for plasmid replication...
February 2017: Applied Microbiology and Biotechnology
Lauren S Mogil, Nicole A Becker, L James Maher
DNA-protein loops can be essential for gene regulation. The Escherichia coli lactose (lac) operon is controlled by DNA-protein loops that have been studied for decades. Here we adapt this model to test the hypothesis that negative superhelical strain facilitates the formation of short-range (6-8 DNA turns) repression loops in E. coli. The natural negative superhelicity of E. coli DNA is regulated by the interplay of gyrase and topoisomerase enzymes, adding or removing negative supercoils, respectively. Here, we measured quantitatively DNA looping in three different E...
2016: PloS One
Alexandra E Paharik, Wilmara Salgado-Pabon, David K Meyerholz, Mark J White, Patrick M Schlievert, Alexander R Horswill
The Spl proteases are a group of six serine proteases that are encoded on the νSaβ pathogenicity island and are unique to Staphylococcus aureus. Despite their interesting biochemistry, their biological substrates and functions in virulence have been difficult to elucidate. We found that an spl operon mutant of the community-associated methicillin-resistant S. aureus USA300 strain LAC induced localized lung damage in a rabbit model of pneumonia, characterized by bronchopneumonia observed histologically. Disease in the mutant-infected rabbits was restricted in distribution compared to that in wild-type USA300-infected rabbits...
September 2016: MSphere
Bandar Sendy, David J Lee, Stephen J W Busby, Jack A Bryant
Chromatin immunoprecipitation, followed by quantification of immunoprecipitated DNA, can be used to measure RNA polymerase binding to any DNA segment in Escherichia coli By calibrating measurements against the signal from a single RNA polymerase bound at a single promoter, we can calculate both promoter occupancy levels and the flux of transcribing RNA polymerase through transcription units. Here, we have applied the methodology to the E. coli lactose operon promoter. We confirm that promoter occupancy is limited by recruitment and that the supply of RNA polymerase to the lactose operon promoter depends on its location in the E...
November 5, 2016: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Allister J Loughran, Dana Gaddy, Karen E Beenken, Daniel G Meeker, Roy Morello, Haibo Zhao, Stephanie D Byrum, Alan J Tackett, James E Cassat, Mark S Smeltzer
We used a murine model of acute, posttraumatic osteomyelitis to evaluate the virulence of two divergent Staphylococcus aureus clinical isolates (the USA300 strain LAC and the USA200 strain UAMS-1) and their isogenic sarA mutants. The results confirmed that both strains caused comparable degrees of osteolysis and reactive new bone formation in the acute phase of osteomyelitis. Conditioned medium (CM) from stationary-phase cultures of both strains was cytotoxic to cells of established cell lines (MC3TC-E1 and RAW 264...
September 2016: Infection and Immunity
Katherine M Stefanski, Grant E Gardner, Rebecca L Seipelt-Thiemann
Concept inventories (CIs) are valuable tools for educators that assess student achievement and identify misconceptions held by students. Results of student responses can be used to adjust or develop new instructional methods for a given topic. The regulation of gene expression in both prokaryotes and eukaryotes is an important concept in genetics and one that is particularly challenging for undergraduate students. As part of a larger study examining instructional methods related to gene regulation, the authors developed a 12-item CI assessing student knowledge of the lac operon...
2016: CBE Life Sciences Education
Stephen B Baylin
No abstract text is available yet for this article.
April 15, 2016: Cancer Research
Valérie Racine
In this paper, I revisit the development of the repression model of genetic regulation in the lac operon to challenge a common application of a conceptual framework in the history of biology. I take Allen's (1978) account of the changes in the life sciences during the early and mid-twentieth century as an example of a common application of a framework based on the dichotomy between a mechanistic, or reductionist, approach to science and a holistic one. From this conceptual framework, Allen infers two general claims about the process of science and its goals: (1) that "mechanistic materialism" has often presented a more practical way to begin the study of complex phenomena in the life sciences, and (2) that the approach described as "holistic materialism" provides a more complete or accurate description of the natural world...
October 2016: Studies in History and Philosophy of Biological and Biomedical Sciences
Robert Gnügge, Lekshmi Dharmarajan, Moritz Lang, Jörg Stelling
Feedback loops in biological networks, among others, enable differentiation and cell cycle progression, and increase robustness in signal transduction. In natural networks, feedback loops are often complex and intertwined, making it challenging to identify which loops are mainly responsible for an observed behavior. However, minimal synthetic replicas could allow for such identification. Here, we engineered a synthetic permease-inducer-repressor system in Saccharomyces cerevisiae to analyze if a transport-mediated positive feedback loop could be a core mechanism for the switch-like behavior in the regulation of metabolic gene networks such as the S...
October 21, 2016: ACS Synthetic Biology
Silvia Heiss, Angelika Hörmann, Christopher Tauer, Margot Sonnleitner, Esther Egger, Reingard Grabherr, Stefan Heinl
BACKGROUND: Engineering lactic acid bacteria (LAB) is of growing importance for food and feed industry as well as for in vivo vaccination or the production of recombinant proteins in food grade organisms. Often, expression of a transgene is only desired at a certain time point or period, e.g. to minimize the metabolic burden for the host cell or to control the expression time span. For this purpose, inducible expression systems are preferred, though cost and availability of the inducing agent must be feasible...
2016: Microbial Cell Factories
Geraldine Fulcrand, Samantha Dages, Xiaoduo Zhi, Prem Chapagain, Bernard S Gerstman, David Dunlap, Fenfei Leng
Escherichia coli lac repressor (LacI) is a paradigmatic transcriptional factor that controls the expression of lacZYA in the lac operon. This tetrameric protein specifically binds to the O1, O2 and O3 operators of the lac operon and forms a DNA loop to repress transcription from the adjacent lac promoter. In this article, we demonstrate that upon binding to the O1 and O2 operators at their native positions LacI constrains three (-) supercoils within the 401-bp DNA loop of the lac promoter and forms a topological barrier...
January 14, 2016: Scientific Reports
Matthew Charles Edmundson, Louise Horsfall
Arsenic is a widespread contaminant of both land and water around the world. Current methods of decontamination such as phytoremediation and chemical adsorbents can be resource and time intensive, and may not be suitable for some areas such as remote communities where cost and transportation are major issues. Bacterial decontamination, with strict controls preventing environmental release, may offer a cost-effective alternative or provide a financial incentive when used in combination with other remediation techniques...
2015: Frontiers in Bioengineering and Biotechnology
Soon-Kyeong Kwon, Seong Keun Kim, Dae-Hee Lee, Jihyun F Kim
Achieving sufficient yields of proteins in their functional form represents the first bottleneck in contemporary bioscience and biotechnology. To accomplish successful overexpression of membrane proteins in a workhorse organism such as E. coli, defined and rational optimization strategies based on an understanding of the genetic background of the toxicity-escape mechanism are desirable. To this end, we sequenced the genomes of E. coli C41(DE3) and its derivative C43(DE3), which were developed for membrane protein production...
November 4, 2015: Scientific Reports
Yamato Ideguchi, Yuta Oshikoshi, Masashi Ryo, Shogo Motoki, Takashi Kuwano, Takafumi Tezuka, Setsuyuki Aoki
We continuously monitored bioluminescence from a wild-type reporter strain of Escherichia coli (lacp::luc+/WT), which carries the promoter of the lac operon (lacp) fused with the firefly luciferase gene (luc+). This strain showed a bioluminescence burst when shifted into the stationary growth phase. Bioluminescence profiles of other wild-type reporter strains (rpsPp::luc+ and argAp::luc+) and gene-deletion reporter strains (lacp::luc+/crp- and lacp::luc+/lacI-) indicate that transcriptional regulation is not responsible for generation of the burst...
January 2016: Archives of Microbiology
Jian Wang, Shaofu Qiu, Xuebin Xu, Wenli Su, Peng Li, Beibei Liang, Qiuxia Ma, Chaojie Yang, Lihua Qi, Hao Li, Shengjie Yi, Zhihao Wu, Ligui Wang, Rongzhang Hao, Hongbin Song, Yansong Sun
Shigella sonnei has become predominant species causing shigellosis in Shanghai. Two hundred ninety-three S. sonnei were isolated in sentinel hospitals of Shanghai in 2011. We found an emergence of 8 strains of S. sonnei with negative phenotype for o-nitrophenyl-β-d-galactopyranoside in late August, which showed distinct pulsed-field gel electrophoresis patterns from the other 285 S. sonnei and had genes deletion in lac and mhp operons.
December 2015: Diagnostic Microbiology and Infectious Disease
Huseyin Tas, Cac T Nguyen, Ravish Patel, Neil H Kim, Thomas E Kuhlman
We describe an optimized system for the easy, effective, and precise modification of the Escherichia coli genome. Genome changes are introduced first through the integration of a 1.3 kbp Landing Pad consisting of a gene conferring resistance to tetracycline (tetA) or the ability to metabolize the sugar galactose (galK). The Landing Pad is then excised as a result of double-strand breaks by the homing endonuclease I-SceI, and replaced with DNA fragments bearing the desired change via λ-Red mediated homologous recombination...
2015: PloS One
Dominik Satory, Alasdair J E Gordon, Mengyu Wang, Jennifer A Halliday, Ido Golding, Christophe Herman
DksA is an auxiliary transcription factor that interacts with RNA polymerase and influences gene expression. Depending on the promoter, DksA can be a positive or negative regulator of transcription initiation. Moreover, DksA has a substantial effect on transcription elongation where it prevents the collision of transcription and replication machineries, plays a key role in maintaining transcription elongation when translation and transcription are uncoupled and has been shown to be involved in transcription fidelity...
December 2, 2015: Nucleic Acids Research
Susan R Leonard, David W Lacher, Keith A Lampel
BACKGROUND: Classical bacteriological characteristics of Salmonella enterica indicate that the members of this species are unable to utilize lactose as a carbon source. However, lactose-fermenting (Lac+) strains of several Salmonella serovars have been isolated from different foodborne outbreaks as well as different geographical regions worldwide. In the present study, we sequenced the genomes of 13 Lac + S. enterica isolates and characterized the lac region, comparing it to the lac region in other enteric bacterial species...
2015: BMC Microbiology
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"