The Lat­est In­tel­li­gence

Alien or­gan­ism cre­ated by adding new let­ters to the ge­netic alphabet could lead to more ef­fec­tive de­signer drugs

BBC Earth (Asia) - - Contents -

Syn­thetic DNA made in lab, in­ter­stel­lar as­ter­oid cap­tured en­ter­ing the So­lar Sys­tem, Stretchy sweat-pow­ered bat­tery made out of fab­ric…

A team of sci­en­tists at the Scripps Re­search In­sti­tute in the US have cre­ated a liv­ing ‘semi-syn­thetic’ or­gan­ism ca­pa­ble of pro­duc­ing pro­teins never seen be­fore on Earth by adding new let­ters to the ge­netic code. The syn­thetic pro­teins cre­ated by such or­gan­isms could pave the way for a new gen­er­a­tion of made-to-or­der drugs and ther­a­pies, the team said.

The reg­u­lar ge­netic ‘alphabet’ con­sists of four let­ters, or bases: A, T, G and C. These stand for ade­nine, thymine, gua­nine and cy­to­sine, which are the four chem­i­cals that make up DNA. These let­ters can com­bine in dif­fer­ent se­quences to form 20 nat­u­rally oc­cur­ring amino acids – the build­ing blocks of pro­teins.

In 2014, the Scripps team cre­ated two more ‘let­ters’, X and Y, mak­ing it the­o­ret­i­cally pos­si­ble to cre­ate a fur­ther 152 syn­thetic amino acids. How­ever, they were un­able to make an or­gan­ism that could pro­duce pro­teins. Now, they have suc­cess­fully cre­ated an or­gan­ism ca­pa­ble of pro­duc­ing so-called green flu­o­res­cent pro­teins by mod­i­fy­ing Escherichia coli – a sin­gle-celled, rod-shaped bac­terium com­monly used in the lab-based man­u­fac­ture of pro­teins.

“This is the first time that pro­teins have been pro­duced in any cell by the de­cod­ing of a six-let­ter ge­netic alphabet, in­stead of just the nat­u­ral four-let­ter alphabet,” said study leader Dr Floyd Romes­berg. “The lim­ited com­bi­na­tions of the nat­u­ral DNA bases, A, T, G, and C, have re­stricted the types of new pro­tein ther­a­peu­tics that could be made. Adding X and Y to the ge­netic alphabet, we now have an ex­panded vo­cab­u­lary to be able to gen­er­ate a va­ri­ety of new pro­teins that might be de­vel­oped for a wide range of ap­pli­ca­tions, in­clud­ing as new ther­a­peu­tics.”

It was pre­vi­ously be­lieved by many re­searchers that our spe­cific DNA struc­ture was es­sen­tial for the evo­lu­tion of life. How­ever, the break­through by the Scripps team opens up the pos­si­bil­ity that life could have evolved in a dif­fer­ent way on an­other planet.

The or­gan­ism is com­pletely safe and has no chance of spread­ing out be­yond the lab and con­tam­i­nat­ing nat­u­ral life forms as it is in­ca­pable of pro­duc­ing the X and Y bases it needs to live by it­self, the re­searchers said.

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