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Plasmid addiction systems: from bacterial toxins to molecular biology tools

Posted by Jennifer Tsang on Nov 1, 2018 8:35:58 AM

Members of the bacterial world produce an assortment toxins to claim territory or kill competing microorganisms, but did you know bacteria also produce substances toxic to themselves?

These toxic substances are part of toxin-antitoxin systems that are widely present in bacteria. They consist of a toxin which can affect a variety of cellular processes and an antitoxin that suppresses the toxin’s activity. The key to these systems is that the toxin is stable while the antitoxin is unstable, meaning that the cells must continually produce antitoxin to avoid cell death.

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Topics: Plasmid Cloning, Plasmid Technology, Plasmid Elements

Plasmids 101: Simplify cloning with in vivo assembly

Posted by Guest Blogger on Oct 18, 2018 8:37:05 AM

This post was contributed by Jake Watson and Javier García-Nafría from the MRC Laboratory of Molecular Biology.

Plasmid cloning is an essential part of any molecular biology project, yet very often, it is also a bottleneck in the experimental process. The majority of current cloning techniques involve the assembly of a circular plasmid in vitro, before transforming it into E. coli for propagation. However, while not widely known, plasmid assembly can be achieved in vivo using a bacterial recombination pathway that is present even in common lab cloning strains.

This intrinsic bacterial recombination pathway, referred to as recA-independent recombination, joins together pieces of linear DNA through short homologous sequences at their termini, and likely functions as a bacterial DNA repair mechanism. The pathway is ubiquitous, with successful recombination reported in all laboratory E. coli strains tested so far.

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Topics: Plasmids 101, Plasmid Cloning

Golden Gate Assembly upgrades: More fragments, faster assembly, and higher fidelity

Posted by Guest Blogger on Oct 11, 2018 8:30:35 AM

This post was contributed by guest bloggers Becky Kucera, M.Sc. and Eric Cantor, Ph.D. from New England Biolabs.

Golden gate assembly limitations

Embraced by the synthetic biology community, Golden Gate Assembly is commonly used to assemble 2–10 DNA fragments in a single “one-pot” reaction to form complex, multi-insert modular assemblies that enable biosynthetic pathway engineering and optimization. However, current best practices for assemblies of more than 10 modules often rely on two-step hierarchical approaches using different Type IIS restriction enzyme specificities at each step. Factors such as enzyme efficiency, stability, and buffer compatibility have placed practical limits on single- or two-step assemblies.

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Topics: Plasmid Cloning

The time and cost required to make a plasmid

Posted by Jennifer Tsang on Sep 11, 2018 9:48:42 AM

Have you ever wondered how long it takes to make a plasmid? Or have you thought about how much total time you spend in the lab cloning before you can start on your experiment? What about all the reagents you need to order? Sometimes, it feels like an eternity of cloning, waiting, and repeating before you can finally dive deep into experiments.

Since one million plasmids shared is upon us at Addgene, we started wondering, just how much time and money do researchers spend cloning? How much does material sharing speed science?

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Topics: Plasmid Cloning, Lab Tips

Plasmids 101: 5 factors to help you choose the right cloning method

Posted by Michael G. Lemieux on Aug 21, 2018 8:31:59 AM

You’ve spent days and weeks thinking of an amazing project. You’ve written your protocols, designed your experiments, and prepared your reagents. You’re going to engineer the best thing since CRISPR; you are ready to clone! But...how?

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Topics: Plasmids 101, Plasmid Cloning

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