Error-free transcriptase
The first fruits of artificial evolution have been obtained
Molecular biologists from the University of Texas at Austin have created an artificial enzyme that allows you to accurately copy genetic information. To do this, scientists have applied the method of directed evolution. An article with the results of the work (Ellefson et al., Synthetic evolutionary origin of a proofreading reverse transcriptase) was published in the journal Science on Friday, June 24.
The genome of viruses belonging to the retrovirus family consists not of DNA, but of RNA. In reverse transcription, RNA plays the role of a template for creating a complementary DNA chain, which is then embedded in the genome of the host cell. This process can be accompanied by numerous errors, and therefore no virus can accurately copy its genetic material. Due to this feature, HIV mutates rapidly, which seriously complicates its treatment.
Since neutralized retroviruses are used for genetic engineering, errors in copying the genome become a problem for scientists who introduce genes into cell cultures. To solve this problem, researchers have developed a special enzyme that not only performs reverse transcription, but also checks the result of its work.
The enzyme is a modified RNA-dependent DNA polymerase, which has been improved by a directed evolutionary process. Scientists have named the new molecule RTX (reverse transcription xenopolymerase — reverse transcription xenopolymerase). Polymerase genes were originally isolated from archaeal cells and belonged to the beta-DNA polymerase family, which already contained a molecular module capable of checking the quality of copying. The genes differed from each other by small mutations, as a result of which the enzymes encoded by them performed their work with different efficiency.
To reproduce natural selection, scientists forced polymerases to self-replicate. After some time, the most widespread were those molecules that copied themselves most efficiently and correctly. RTX makes errors 3-10 times less than existing natural enzymes.
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27.06.2016