coli cannot maintain the genome as it can routine plasmids

buy canada goose jacket cheap Engineering Viruses is Hard buy canada goose jacket cheap

Canada Goose sale The virus has locked inside itself a puzzling conundrum. While the virus utilizes 11 different proteins, there is buy canada goose jacket not enough canada goose uk outlet viral DNA to encode all canadian goose jacket of them. The combined length of the 11 proteins is 2327 amino acids, but the genome is Canada Goose sale only 5386 nucleotides in length. Ignoring regulatory sequences, the most that a 5386 base genome can encode is a mere 1795 canada goose coats amino acids (= 5386/3). That’s 532 amino acids short, leaving nearly a quarter of Canada Goose Online the proteins of Canada Goose Coats On Sale mysteriously unaccounted for. Canada Goose sale

canada goose black friday sale The answer to this puzzle canada goose black friday sale shows how flexible biology can be. It turns out that the genome does encode all 11 proteins, but that some of the protein coding genes overlap. This is uk canada goose outlet possible because the genetic code set cheap Canada Goose of rules for converting a DNA or RNA sequence to a protein sequence such that uk canada goose three DNA or RNA bases (a “codon”) code for one amino acid. Two protein coding sequences can be overlaid in the same DNA sequence by utilizing overlapping sets of codons (see the figure; alternative ATG start codons underlined). canada goose black friday sale

canada goose clearance sale This overlapping genetic system means that can efficiently package its genome into its viral coat. And, since a Canada Goose Outlet smaller genome requires fewer resources, more viruses can be built canada goose clearance from the finite resources of each E. coli cell before the cell bursts. However, the genetic system is by virtue of its extreme compactness and overlapping genes hard canada goose clearance sale to engineer, and so a team at Stanford University decided to “decompress” buy canada goose jacket cheap the genome1. canada goose clearance sale

canada goose store As expected, a “full length” genome with all overlaps removed but all coding sequences preserved would be much longer, and therefore the resulting viruses would be less fit. Since the question of interest is the canada goose factory sale effect of the overlaps, rather than the effect of the genome length, the team used a synthetic genome with most of the F gene deleted to accommodate the increased length created by extending out overlaps. Thus a fair comparison can be made between the decompressed genome and the wild type genome. The F gene canada goose coats on sale was knocked into the genome of their E. coli strain, allowing the virus to function normally. canada goose store

canada goose coats on sale With this new ” genome designed, the team used synthetic DNA and PCR amplification from the wild type genome for assembly. They used yeast to help cheap canada goose uk assemble and maintain the synthetic genome, in a similar fashion as Craig Venter’s https://www.canadagooseoutletstore.co.uk team did when assembling the Canada Goose online synthetic Mycoplasma genome2. Obviously E. coli cannot maintain the genome as it can routine plasmids, since the genome instructs the cell’s destruction by viral infection. However, yeast (eukaryotes, like us) are perfectly happy to Canada Goose Jackets serve as an archival system for maintaining the genomes of viruses that infect bacteria. Canada Goose Parka coli transformed with the yeast archived viral genomes succumbed to infection. Cleverly, the F gene knocked into the E. coli genome (to compensate for the truncated version in their decompressed virus) was regulated by an inducible promoter. By changing the concentration of the sugar rhamnose in the growth media, the researchers could control the severity of the viral infection. Not surprisingly, the wild type outperformed their decompressed version. When agar plates covered with E. coli are infected with clear circles called plaques form, a visible mark of the dismemberment of canada goose uk black friday billions of E. coli cells. Infection with wild type produced plaques on average 4.9 mm across; infection with their decompressed strain under full rhamnose concentration produced plaques on average 4.1 mm across. canada goose coats on sale

canada goose coats This new virus could be an important platform for viral synthetic biology. The genome is small enough to be made cheaply, so that the design, tinker, redesign process is feasible. Viruses like are far canada goose uk shop simpler than the bacteria they infect, so why not start here? Famous and well funded biologists like Craig Venter and George Church3 are trying to design new bacteria from scratch. That’s quite a tall order. I really want them to succeed, but I have my doubts. canada goose coats

buy canada goose jacket New designs rarely work the first time, even when we are talking about only a couple genes sitting on a plasmid in E. coli. Designing a whole genome will surely require canada goose extensive tinkering and revision. Since viral genomes are far simpler, it seems to make sense to start there. I think a completely new virus could with relative ease be put together from parts strewn across the catalog uk canada goose of thousands of known genes (viral or otherwise). That’s canada goose store the sort of design work that we are talking about with synthetic cells; nobody expects us to make a genome full of new genes, let alone a completely new biochemistry. Designer cells will be made of known genes, assembled together by human design. What we learn from making designer viruses could help us in the pursuit of new living cells of human design buy canada goose jacket.

Leave a Reply