A chunk of the genetic blueprint for yeast has been created and pieced together from scratch, paving the way for "designer" organisms that could produce new medicines, food products and biofuels, the creators say.

Researchers took tiny snippets of man-made DNA and joined them together to create a synthetic version of a chromosome, the structure that contains DNA inside cells, from brewer's yeast. The ability to create such chromosomes is a major step for the field of synthetic biology, which aims to engineer microbes to produce useful products. The work also brings scientists closer to creating synthetic plants and animals.

"For me, one of most exciting aspects is the fact that we've so extensively edited the sequence of natural chromosome and then synthesized the entire thing from scratch," said study leader Jef Boeke, a synthetic biologist at NYU Langone Medical Center, who was previously at Johns Hopkins University.

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To create the artificial chromosome, Boeke and his team used computer software to design a modified version of yeast chromosome III, which they called synIII, and incorporated it into brewer's yeast (Saccharomyces cerevisiae). They chose this chromosome because it is one of the smallest of yeast's 16 chromosomes and controls how the cells mate and experience genetic changes.

It took the researchers seven years to stitch together the synthetic chromosome from pieces of DNA. The language of DNA consists of four "letters" — A, T, G and C — which form bonds called base pairs. The synIII chromosome contains 272,871 base pairs, slightly fewer than the 316,617 base pairs in chromosomes of native yeast, or natural yeast on which the simulated one is based. Undergraduate students at Johns Hopkins University did much of the work fusing together short pieces of DNA into longer segments, as part of a class project, and some of these former students were co-authors on the study.


http://m.csmonitor.com/Science/2014/...ial-chromosome