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Synthetic biology Genome engineering Chris Yellman, U. Texas CSSB
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What is synthetic biology? synthesis: the combination of two or more parts to make a new product greek: synthetos, “put together, constructed, compounded” examples: rearrangements of existing DNA sequences to make new genes, gene fusions, new regulatory elements production of chemicals and drugs with biological activity synthetic insulin (a peptide hormone) made in yeast or E. coli antibodies, such as anti-toxins for snake venom genome synthesis or genome rearrangement: can make genomes that have never existed
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What makes synthetic biology possible? 1 sequence data from natural genomes - bacteriophages and other viruses -bacteria such as E. coli but many others as well -eukaryotes from yeast to humans (full evolutionary spectrum) 2ability to synthesize DNA, RNA, proteins -oligonucleotides, entire genes -peptides (pieces of protein) 3 purified enzymes -DNA polymerase for PCR amplification of DNA from templates -restriction endonucleases to cut DNA at specific sites 4 model organisms with well understood biology -E. coli, a prokaryote, phages and viruses -Saccharomyces cerevisiae (yeast), a eukaryote -Drosophila (fruit fly), C. elegans (worm), mouse, human cells (stem cells, other cell lines)
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What makes synthetic biology interesting? 1make useful natural products -insulin -artemisin (current best anti-malarial drug) -ethanol, other bio-fuels 2make new model systems 3 intervene in biological systems to figure out how they work, for example rearrange the genes in a bacterial operon 4understand the limitations of evolution and perhaps augment biology with additional amino acids or protein coding 5understand the origins of life – can we make a completely artificial cell?
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Can we make life abiotically (from non-living material)? Jack Szostak’s model of a protocell
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using redundant codons to expand the genetic code non-natural amino acids can be incorporated into proteins
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DNA synthesis: the basis for much of synthetic biology 1oligonucleotides 2genes 3chromosomes 4 genomes DNA of almost any size can now be made entirely in vitro
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oligonucleotide synthesis
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entire yeast chromosomes have been made in vitro Dymond et al., 2011, Nature, Saccharomyces Genome Database
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an entire synthetic genome: M. mycoides JCVI-syn1.0 1 kb assemblies in vitro from oligonucleotides 10 kb assemblies in yeast 100 kb assemblies in yeast assembly of the 1.1 mb genome in yeast on a CEN-ARS plasmid Gibson et al., 2010, Science
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DNA assembly: making meaningful parts 1genes, promoters and terminators can be assembled to make operons or bring the genes under different regulation 2centromeres and origins of replication are included to give synthetic DNA the properties of native chromosomes 3genomes can be assembled to mimic known genomes or to create completely artificial new genomes with genes from different species
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“Recombineering” 1based on homologous recombination in vivo or in vitro -nucleotide base pairing is one of the most fundamental principles in biology -can occur between DNA and/or RNA strands 2E. coli and yeast both repair their genomes by homologous recombination 3using live organisms “in vivo” takes advantage of natural enzyme activities, DNA repair and proofreading processes, etc. 4in vivo hosts have different properties
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Escherichia coli
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Saccharomyces cerevisiae Roberta Kwok, 2011 Nature
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Recombineering using E. coli and yeast 1synthesize by PCR 2Use E. coli with phage enzymes that promote homologous recombination 3multiple linear pieces of DNA are co-transformed into the bacteria, where they are assembled by the endogenous enzymes 4we can also modify the native chromosomes of bacteria and yeast
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Gibson assembly (NEB), an in vitro method Assembly in vitro using purified enzymes “one pot”. Works for multi-piece assemblies.
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Full-length RecE enhances linear-linear homologous recombination and facilitates direct cloning for bioprospecting Fu et al., 2012 nature biotechnology Ryan E Cobb & Huimin Zhao nature biotechnology, 2012 Court lab, NIH
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multi-piece assembly of ds PCR fragments in yeast
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moving genes and pathways between species creating mutant libraries of genes to study the genetic basis for diseases bio-prospecting for useful enzymes or other molecules Genome engineering
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native bacterial “immunity” to phages
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title
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How CRISPR/Cas9 will change eukaryotic biology inducing double-strand breaks leaves damage that gets repaired by the cells the repair process can be used to insert new DNA new DNA can be disease alleles of genes, GFP fusions to genes, etc…
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