Why is it difficult to rewrite the genome?

When Patrick is reflected, Kai is shaken on the state of artificial genome, he remembers the large DNA competition. A competition was launched in 2004, and artificial biologists have learned to design a 40,000 -bare functional DNA sequence, which will be made by Blue Heron Biotech (now Eurofins Genomics Blue Heron) for free.

It was not a small prize: at that time, this modest slab from DNA – is produced less than 1 % length Show the cold Genome – it may cost about $ 250,000. The company’s goal was to stimulate the field of artificial biology at the time. “In the end, zero requests have been received,” says Cai, the artificial biologist at Manchester University, UK. “This tells you that even if you can make artificial DNA for free, no one has enough imagination 20 years ago.”

Today, fixed progress in genome and computer biology-not to mention the synthesis and assembly of DNA-has made multiple examples of what an ambitious effort and genome formation can achieve. JCVI-SYN3A, developed at the J Mecoplasma Micoids This remains and repeated despite stripping several hundreds of unnecessary genes1. Various groups are engineering Cola The strains in which the genetic code has been changed to enable the production of proteins that contain amino acids that exceed twenty that are usually observed in nature. Last year, the SC2.0 Anti -National Yeast project (SC2.0) completed the construction of severe engineering versions of each chromosome in soft nuclei yeast, SACCHAROMYCES CEREVISIEE It includes about 12 million pairs base in all.

Akos Nairers, an artificial genome researcher, says these efforts were invaluable educational experiences. Cola Rewriting the effort at the George Church Laboratory at the Harvard University College of Medicine in Boston, Massachusetts. “You can imitate and test the evolutionary steps that could take billions of years to develop – or have not evolved at all,” he says. But they also put naked how much we still do not understand them about the basic language of the genome. Each genome cavity program has so far struggled with great and unexpected challenges, and the on -handed genome era is still far from hand. “We have reduced the complexity of biology,” says Nairers.

Return to the basics

Most of the artificial genome projects are efforts “from top to bottom” that take a natural object that occurs naturally and comes out or re -design its DNA. This provides a valuable initial frame for the “from the base to the top” approach, where the goal is to build a working genome from the zero point. After all, Varine Ishaq, Jenome’s engineer at Yale University in New Haven, explains, when it comes to messing with jeans, the margin of the error is surprisingly minimal. “If you create an error in a basic gene, you will wipe the organism.”

The main goal of JCVI and SC2.0 projects was to define the necessary genes – a surprisingly difficult feature. John Glass, leader of the JCVI artificial biology program, says that when he and his team were published2 Their report of 2016 on the minimum of their cell, nearly a third of the remaining genes of the cell (149 out of 473) had no known function. “I would like to say it’s 78 now,” he added.

To determine the genes that were necessary, both projects used random mutations – mainly, leading to unrefined disorders throughout the genome and ask about which cells that can tolerate them and which of those that have been strongly said of cellular feasibility.

But the basis is a slippery concept, especially given that most of the genomics contain repetition and “safe failure” mechanisms to reduce the effect of individual mutations. Glass and his colleagues faced dozens of cases in which the mutations have revealed pairs of different genes that seem to perform unexpectedly overlapping functions. As a result, there is no simple genome, as explained. “You take one [gene]And with each option, you are going on a different way to a slight minimum of the cell. “Moreover, many bacterial genes have multiple functions, which makes it difficult to recognize the basic function. Desired.

The increasingly advanced “full cell models” can help remove some guesses from the future genome efforts. In 2020, mathematics, Lucia Maruchi and the Persian District Storm Claire Jerson, both at Bristol University, UK, led an attempt to simulate the genome -limiting strategies in a full cell model of Mycoplasma genitalia Close to the microorganisms that JCVI edited3. They suggested their analysis, which used detailed models for cellular processes and its interactions, redesigning with distinctive groups of deleted genes, each yield is almost $ 40 % smaller than normal M. Gentures Genome.

Recently, Marucci and GREERESON have started working with complex developed cell models Cola. As shown in 2024 Preprint4Their current efforts combine mechanical models and machine learning to predict the consequences of junum manipulation through a wide range of biological functions. It is described by thousands of interconnected equations, which result Cola. “We now have a set of reduced genomics that we want to test in the laboratory,” said Maruchi.

Search and replace

Instead of making brief versions of the genome, other groups have started to formulate the genetic text skillfully – and face a completely different set of challenges.

Protein coding sequence is designed from three nucleotides known as codes. With 61 potential symbols of 20 amino acids that occur naturally as well as 3 “stop” code that end protein synthesis, there is a great repetition of the resulting code. Various teams have shown that by converting each comprehensively comprehensively from a specific code to one of its “synonyms”, one can re -display this code. This month, for example, Isaac and his colleagues described Cola A strain called Ocher where two stop codes were reset to direct the inclusion of abnormal amino acids to-Asity-toFenell Alanin and nE-Buk-to-Lysine5. These amino acids have chemical properties and functions that are not present in nature, but remedy can also be a “protection wall” that prevents the interaction and exchange of genetic materials with other organisms in natural environments.

This work may seem clear – simply replacing Kodon for another – but the genome reproach requires a lot of planning and effort. After the researchers found all cases of codon they want to eliminate, they must then know how to replace it without disrupting infected genes or organizational machines. Bacterial genes often contain organizational sequences in the protein coding sequence, as NYERISES indicates, and the gene can interfere with one rope of DNA with a gene on opposite rope. Simple changes can have no expected severe consequences.

Nyerges, the church and their colleagues wrestle with this challenge on an unprecedented scale, where they end a variable that has been coded severely. Cola Which uses only 57 of 61 amino acid codes that occur naturally6. This effort necessitated more than 73,000 changes in a 4 -megabyte dynamic genome, which inevitably creates unintended effects. “Some things will happen easily without any effect on growth or fitness, while others have an amazing effect,” says Neerge. Some disabled changes are the current organizational elements or were unintentionally created; Others created a new protein coding sequence. “We only learn about this as we go.”

Poles created by computer for the synthetic cell created by researchers at the JCredit: Zaida Luthey-Schulten

Sorting these issues is a great task in itself. For example, during the process of re -coding of their magnetic dynasty, Isaac and his team used large -scale “multiple” analyzes of bacteria. “We have collected metaphorical stereotypes under different [culture] He says. “We have also collected proteins data that compare the coded cell with a few different predecessors, including wild cells.” In this way, they systematically adjusted the genome so that the cells could grow under the standard culture conditions with almost the rate of almost not modified bacteria-which is not trivial, given that the genome coding often weakens growth. Nererg and his colleagues similarly turned into a multi -party to explore the 57 code genome. They also used an experimental strategy that stimulates the rapid development of bacteria in culture, to enhance the choice of genome mutations that improve fitness.

The algorithm tools also help researchers design and predict the results of some genome regeneration experiments in advance. For example, the artificial biology team Howard Salis at the Pennsylvania State University at Park University is used as data of highly productive screens from both genetically modified cells of artificial DNA to develop algorithms that can determine, describe and describe the design sequences that are governed by copying and translation . “A typical paper for us at the present time ranges between 10,000 to 100,000 different and designed different experiences,” Sallis says. Results are used to extract testable physical principles that allow algorithms to predict, for example, how changes change in the meadow sequence of gene expression.

“You can turn everything,” says Salis. “We can combine our current models to design the following experiences to understand the remaining things that are misunderstood.” In fact, the church laboratory used many salis tools to design its microbe 57 code. Nairers says that such algorithms were a great advantage – although not enough to prevent and repair errors. “Even very small changes can cursedly lead to important physical fitness problems by simply adding thousands of genes to the genome,” he says.

Feeling a nuclei realization

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