China and CRISPRs

CRISPRs grew in prominence in the last few weeks. It was the breakthrough in molecular biotechnology that prompted the very first larger-scale CRISPRs ever to be synthesised (23 December).

One of the tricky points that people are still wrestling with is that conventional molecular biotechnology is only able to achieve short-term and temporary changes at the genome level. For a molecular scientist, being able to influence the DNA directly is pretty much just a gimmick, used for example to control a single gene from his or her respectable workstation. Words like ‘genome editing’ are ones that come up often when we discuss what’s possible when it comes to your everyday mutated mouse gene.

But the most exciting CRISPR news came on 12 December when a paper published in Nature found that non-transgenic rhesus macaque (Macaca mulatta) cells could be targeted with an RNA molecule, and had the capacity to form fluorescent proteins—a development that could be taken as a major step toward radical gene editing.

When it comes to bacteria, it hasn’t been long since more and more papers that sought to help in various biological areas, including that of DNA replication, were published. That is, the idea that bacteria could be coaxed to repair genomes at will seems to have hit its stride. For example, the strategy is being imagined for environmentally-damaging plagues, and left-over pieces of DNA could even be used to edit them back together at a molecular level.

But the effects of such genetic fixes tend to be short-term. They are based on an advantageous genetic tweak that is bound to be swapped out each generation. The upside, of course, is that the organism is safe for a short while, and then, unfortunately, die. Such tricks are called incessant perhaps, but extra copies of the error-prone parts of genes could at least give back a potentially useful care and feeding instruction to bacteria.

The new work among bacteria is still in its early stages. But the idea is to write instructions to that amount of garbled DNA, which can be either short or long. For example, if one haploid cell is tagged with a short-range CRISPR sequence, such as a shorter version of a specific gene, it becomes a sort of ‘mirror image’ copy of that gene for a cell with an overlapping DNA helix. The flipped copy then promotes the biochemistry that the ‘right’ copy ought to be doing.

The thing with CRISPR is that it can’t be inadvertent, although now explained Reuven Shtein told PhysOrg.com : “The fact that we can use unconventional (non-DNA) signals to fix a gene in bacteria raises awareness of the harm that can be done by unnatural approaches that fail to stop the process, such as the intractable intractable bug that causes the disease smallpox … There is a fear that these modifications will only drive more success in organismal biotechnology.” Shtein, an associate professor of molecular biophysics at Yale University, was the first to prove that CRISPR-Cas9 could enhance bacteria’s self-repair ability.

“If people are ever going to be able to effectively apply CRISPR-Cas9, we need various mRNA or RNAs that don’t induce any sort of cellular death and damage,” said Shtein.

“Generally speaking, the high fidelity of CRISPR modifications, the sheer number of molecules that can be targeted, and the fact that we can correct and modify these very small genetic points all point to DNA modified in the dot of a 70-million-square-kilometre-slice,” Shtein said. “That is the same silencing system that is used to guide infections. That is a demonstration that we can do without killing the bacteria, that is there is no bogus [self]death mechanism by DNA damage.”

Resistance: RNA helicases

There are four types of delicate crystal keepers of RNA, including helicases.

The helicase messenger RNA (mRNA) is the code for the drug-like protein comprising the molecular building blocks of RNA. On joining, it holds the bundle while ensuring that the groove at the cut site aligns with the RNA oligomer.

Again, Shtein said in an email: “What we see in the immunization work is that these libraries use it [the mRNAs] to store RNA molecules, and scaffold them to form nanopheres. The setting up enzymatic interactions in the library blocks the breakage of RNA molecules, but does not repair it.