Synthetic Biology at Nature Methods

Since its launch, Nature Methods has seen many papers that have influenced the Synthetic Biology community. As a supplement to our May Focus on Synthetic Biology we take a nostalgic trip through the highlights of our papers in this area for different aspects of synthetic biology.

Cloning
In 2007 Stephen Elledge and Mamie Li developed SLIC (sequence and ligation-independent cloning) a strategy that uses homologous recombination to assembly many DNA fragments in vitro in a single reaction. Later the same year Mitsuhiro Itaya and colleagues also used homologous recombination in their bottom up assembly to unite larger DNA pieces to genomes of ~ 140kb size.

In 2009 Daniel Gibson and colleagues presented their one-pot enzymatic reaction that successfully assembled genomes 100s of kilobases and has since been dubbed ‘Gibson Assembly’.  The method reached fame on Youtube when the Cambridge iGEM team for 2010 created a music video showing how Gibson Assembly saves frustrated scientists:

Gene and genome synthesis
In 2007, to improve error-free DNA synthesis, Duhee Bang and George Church developed circular assembly amplification that eliminated error-containing oligonucleotides from the assembly. A few years later  Jay Shendure and colleagues introduced their dial-out PCR to retrieve desired DNA molecules from a library  for gene assembly.

For an in depth review on the topic of DNA synthesis, error correction and gene assembly visit Sriram Kosuri and George Church’s review in our Focus issue.

In 2010, on the heels of their breakthrough with Mycoplasma mycoides JCVI-syn1.0 – the first chemically synthesized bacterial genome (Gibson D, et al Science 329, 2010) ­- Gibson et al. published the chemical synthesis of the mouse mitochondrial genome in our pages. They adapted Gibson Assembly to begin at the oligonucleotide level to rapidly make larger fragments that were then combined into the desired genome, exclusively in vitro.  Once synthesized a bacterial genome might need to be further modified, but to do so in an organism other than E. coli proved challenging. In 2013 Bogumil Karas et al, showed that whole genomes, as large as 1.8 megabases can be directly transferred from bacteria to yeast where genetic manipulation is routine.

In our current Focus issue Gibson reviews the state of the art in genome assembly techniques , compares strategies and discusses what the future may hold.

Genome modification
To quickly generate large libraries of promoters in targeted regions of a bacterial chromosome  George Church and colleagues presented coselection MAGE (multiplex automated genome engineering) in 2012.  The increasingly popular CRISPR system can also rapidly edit genomes with few off-target effects when Cas9 is used as a nickase as William Skarnes and colleagues showed earlier this year.

Gene activation can be tuned by targeting transcription factors via the CRISPR-Cas9 system as Charles Gersbach demonstrated in 2013.

Circuit design
To ease construction of complex circuits Adam Arkin and colleagues adapted known translational regulators to control transcriptional elongation in 2012.  A bit later the same year Jim Collins and colleagues showed that an iterative plug-and-play method makes use of a large repository of genetic components when designing circuits.  This year Jeff Tabor and colleagues showed how gene circuit dynamics can be controlled with light. On April 28 Douglas Densmore and his team introduced Raven , software that calculates assembly plans for complex circuits.

Parts characterization
To be successful in any of the above applications one needs reliable and well characterized parts. Last year Drew Endy, Adam Arkin and colleagues presented a method to quantify the performance of genetic elements and in a companion paper they introduced a library of standardized transcription and translation initiation elements available through biofab.

Towards the end of 2013 Christopher Voigt and colleagues expanded the designer’s toolbox with over 500 well characterized transcriptional terminators. Robert Landick discussed how these ‘better stop signs’ as he termed them provide insight into the mechanism of termination.

UPDATE: There is now a joint special on Synthetic Biology at nature.com/synbio with articles from Nature, Nature Reviews Microbiology and Nature Methods.

Enjoy reading. The papers mentioned above are listed below in chronological order.

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Carbo loading

This morning, I noted the huge amount of combinations that could possibly occur for a 100 nucleotide RNA sequence. Peter Seeberger of ETH Hönggerberg, where Synthetic Biology 3.0 is being held, kicked the complexity up a notch by talking about carbohydrates. The trouble with carbohydrates is synthesis. Proteins and nucleotides are generally quite easy to synthesize through either chemical or biologic means. Carbohydrates present a formidable challenge however.

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Power, Secrets, and Synthetic Biology

“When is secrecy justifiable?” asks Laurie Zoloth, a bioethicist from Northwestern University in a hurried presentation on the ethical challenges presented by synthetic biology at the third annual meeting on the topic in Zürich, Switzerland. She characterized the main arguments that have been made for and against synthetic bio referencing everyone from Kant to Sissela Bok, and Disney to Lucas.

Zoloth delineated the battle lines between scientists who think the technology is ‘cool,’ call them enthusiasts, and academics, ethicists, and pundits who urge caution. One person urging caution, Jim Thomas of the Etc. advocacy group (who has contacted me and even posted links to his own blog on my previous posts), got his say in the panel session that followed the talk. Some fireworks ensued.

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Rabble Rousing 3.0 (Surprise, Berkeley is the Source of the Upheaval)

In all the session on intellectual property at Zurich’s Synthetic Biology 3.0 meeting didn’t quite have the inspirational flair of its science based predecessors, but one talk in particular stood out. Stephen Maurer, a lawyer and adjunct faculty member at Berkeley presented as a case study for the murky intellectual property issues raised by synthetic biology a pending $500 million proposal by the UC school to partner with BP (the B stands for Beyond, now, not British as was formerly the case). For background see here, here and here.

BP is looking to capitalise on synthetic biology for the creation of biofuels and is looking both at Berkeley, considered one of its major hubs at the moment, and the University of Illinois to start setting up shop in an academic setting. Maurer has an intimate vantage, and an interesting point of view.

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Transplant is Neat, But for Assembly, Nature Still Has Us Beat

Questions about the infamous Venter patent didn’t come up at Hamilton Smith’s talk this morning. Smith, a Nobel Laureate and well known as J.C. Venter’s right hand man talked about an ongoing project at the Venter Institute to define a minimal set of genes needed for life. The minimalist Mycoplasma genitalium has been the focus of study for its already sparse genome (it’s about 580 kb long and contains just under 500 genes).

Smith talked about three ongoing projects on M genitalium: 1) reducing the genome to its lowest number of necessary genes, 2) synthesizing and assembling a new M. genitalium genome from scratch for the purpose of 3) transplanting it into a recipient cell and creating essentially a new organism which Smith called M. laboratorium.

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Synthetic Biology … What is That Again?

From a quiet Sunday morning, the synthetic biology meeting in Zürich Switzerland quickly exploded to roughly 300 in attendance. I had a chance to grab Tom Knight of MIT who demurred only slightly when asked about his involvement with synthetic biology. You might call him a founding father of the field. “I gave it a name at least,” he told me as we waited on a long lunch line amongst the other synth biologists grumbling that the cafeteria would only accept Swiss francs.

He was happy to give me some help in trying to define the field.

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