The building blocks of DNA have been expanded by scientists who have created a semi-synthetic organism that is stable that is able to produce biological compounds that have never been seen before.
NEW LIFE-FORM RESEARCHERS DEVELOPED HAVE SIX NUCLEOTIDES NOT FOUR
DNA makes up all things that are living on Earth, and it is made up of four nucleotides that are basic. However, the new life-form researchers in the United States have developed have six, and this leads to things becoming very interesting. The SSO, or semi-synthetic organism, that has been engineered by a team from Scripps Research Institute in California has been made up from the four regular nucleobases that humans are.
These are adenine, cytosine, guanine, and thymine, but it also has two nucleotides that are unnatural too. This means that it gets two more letters, X, and Y in the DNA base pairs, which are essentially the rungs of the ladder that hold the helix spirals of the DNA together.
Members of the research team engineered the same kind of synthetic DNA base pair in 2014, and this revealed that it could be incorporated into E. Coli bacteria that had been modified. This led to the creation of the first-ever living organism with extra letters in it, and it also gave way to the expansion of genetic code that could essentially allow for new types of biological process. However, there was an issue, and this was with the stability. The semi-synthetic organism was able to hold onto its unnatural nucleotides, but it was unable to maintain them when cells were dividing, indefinitely.
CRISPR-CAS9 WAS USED BY RESEARCHERS
Floyd Romesberg, the senior lead researcher, said that the genome is not only stable for a day; it needs to have stability over the scale of a lifetime. He went on to say that if the semisynthetic organism was going to be an organism, then it has to be able to maintain the information in a stable condition.
To work around this, the researchers came up with a way for the semi-synthetic organism to be able to hold onto the X and Y base pair that was unnatural. This was made possible due to a nucleotide transporter so that better DNA replication was better, a Y molecule that was optimized and an engineering system that was refined and which made use of CRISPR-Cas9.
RESEARCHERS REVEALED FIRST STABLE ORGANISM WITH 6-LETTER CODE IN JANUARY
The results of this were first revealed in January and it was the first ever organism formed that was stable using the 6-letter genetic code.
Now a new study has been published and the researchers have revealed that more improvements of that kind have been made to the molecular stability thanks to semi-synthetic bacterium that is able to transcribe and then translate the unnatural X and Y nucleotides with the exact same efficiency as the natural nucleotides, which are A, C, G, and T.
Thanks to a new transcription process the organism is able to synthesize proteins that contain the non-canonical amino acids and this is a process that might shed new light on ways of replicating molecules with reliance that is less on hydrogen bonds.
The team of scientists said in a paper that this showed that for each step of information storage and its retrieval, the hydrogen bonds, which were central to the natural base pairs, might be in some part replaced with packing that was complementary along with hydrophobic forces. Despite the mechanism of decoding, which was said to be novel, the codons could be decoded just as efficiently as their natural counterparts.
BY-PRODUCTS ARE FIRST GENERATION DERIVED PROTEINS NEVER SEEN BEFORE
The scientists have revealed that the by-products are the first of a new generation of derived proteins that are semi-synthetic and which have never before been seen in nature due to them having stable and indefinite incorporation of the base pair that is unnatural. The researchers said that they had examined the decoding of the two unnatural codons and the UBP is not likely to be limited to them.
They went on to say that the first SSI that was reported is thought to be only the first of the new type of semi-synthetic life that can gain access to a wide range of forms and functions that have not been available to natural organisms. At the moment the researchers do not know where this is going to lead, however, one thing is for sure and this is that complexity of life on Earth has taken a huge step forward.