RNA

Credit: CC0 Public Domain

Chemists at Scripps Research have made a discovery that supports a surprising new vision of how life on our planet originated.


In a study published in the Journal of Chemistry Applied Chemistry, They showed that a simple compound called diphosphate (DAP), which was reasonably present on Earth before the advent of life, could have chemically bound small DNA building blocks called deoxynucleosides into strands of primitive DNA.

The finding is the latest in a series of discoveries, over the past several years, indicating that DNA and its close chemical cousin RNA may have emerged together as products of similar chemical reactions, and that the first self-replicating molecules – the first life forms on Earth – were a mixture of the two.

The discovery may also lead to new practical applications in chemistry and biology, but its main significance is that it addresses the ancient question of how life on Earth arose for the first time. In particular, it paves the way for more comprehensive studies of how self-replicating DNA-RNA mixtures evolved and spread on primitive Earth, and ultimately implanted the more mature biology of modern organisms.

“This finding is an important step toward developing a detailed chemical model for how the first life forms on Earth arose,” says lead author Ramanarayanan Krishnamurthy, Ph.D., associate professor of chemistry at Scripps Research.

This discovery also pushes the field of origin of life chemistry away from the hypothesis that has dominated it in recent decades: the “RNA World” hypothesis assumes that the first complications were based on RNA, and that DNA only arose later as a product of RNA life forms.

Is RNA Too Sticky?

Krishnamurthy et al. Questioned the RNA world hypothesis in part because RNA molecules may have been simply too “viscous” to function as first self-replicating.

A strand of RNA can attract other individual building blocks of RNA, which they stick to forming a kind of mirror-image thread – each building block in the new strand attaches to the complementary building block on the original strand, the ‘template’. If the new thread can separate from the die strand, and by the same process, begin to form other new strands, this means that it has achieved the achievement of self-replicating that lies beyond life.

But while RNA strands may be good at forming complementary strings, they are not good at separating from these strands. Modern organisms make enzymes that can force double strands of RNA to go separate ways, thus enabling reproduction, but it is unclear how this could be done in a world where the enzymes did not yet exist.

Chimeric solution

Krishnamurthy and colleagues have shown in recent studies that “chimeric” molecular chains that are both part of DNA and part of RNA may be able to circumvent this problem, because they can elicit complementary strands in a less viscous way that allows them to separate relatively easily.

Chemists have also shown in research papers that have been widely cited in the past few years that the simple ribonucleoside and dioxinucleoside building blocks, from RNA and DNA respectively, could have originated under very similar chemical conditions on early Earth.

Moreover, they reported in 2017 that the organic compound DAP could have played a critical role in modulating ribonucleosides and binding together in the first RNA strands. The new study shows that, under similar conditions, DAP could do the same with DNA.

“We found, to our surprise, that using DAP to interact with deoxynucleosides works best when not all dioxinucleosides are the same but are instead a mixture of different ‘letters’ of DNA like A and T, or G and C, like real DNA,” he says. First author Eddie Jimenez, Ph.D., postdoctoral researcher in Krishnamurthy Lab.

“Now that we better understand how primitive chemistry might have made the first RNAs and DNA, we can begin to use them on a combination of the building blocks of ribonucleoside and deoxynucleoside to see which chimeric molecules are forming – and whether they can self-reproduce and evolve,” Krishnamworthy says.

He notes that the work may also have wide practical applications. The artificial synthesis of DNA and RNA – for example in the “PCR” technology that underpins COVID-19 tests – is up to a world wide standard, but it relies on relatively fragile enzymes and thus has several limitations. Krishnamurthy says that powerful, enzyme-free chemical methods for making DNA and RNA may become more attractive in many contexts.


The building blocks of DNA and RNA could appear together before life on Earth begins


more information:
Ramanarayanan Krishnamurthy et al, Prebiotic Phosphoryization and Oligomerization Concomitant with Deoxynucleosides for DNA Formation, Angewandte Chemie International Edition (2020). DOI: 10.1002 / anie.202015910

the quote: The discovery reinforces the theory that life on Earth arose from the combination of RNA-DNA (2020, December 28) Retrieved December 28, 2020 from https://phys.org/news/2020-12-discovery-boosts-theory-life- earth.html

This document is subject to copyright. Notwithstanding any fair treatment for the purpose of private study or research, no part may be reproduced without written permission. The content is provided for informational purposes only.

READ  알래스카 밤하늘의 오로라 사이에 이상한 나선이 나타납니다.
답글 남기기

이메일 주소는 공개되지 않습니다. 필수 필드는 *로 표시됩니다

You May Also Like

대부분의 금속 로켓이 하늘에 있는 큰 구멍으로 들어갔습니다.

United Launch Alliance의 Delta IV Heavy 로켓이 화요일에 마지막으로 발사되었습니다. 유나이티드 런치…

7,100만년 동안 잠을 자고 있는 새로운 공룡 종은 그들이 새처럼 잤다는 것을 암시합니다

약 7,100만 년 전, 작은 수각류 공룡이 화석 기록의 일부가 되기 전에…

아이슬란드에서 오로라 사냥하기

밖에서 보면 매일 밤 아이슬란드 하늘을 가로질러 북극광이 춤을 추는 것처럼 보일…

블랙홀은 우리 우주에 대한 놀라운 비밀을 숨기고 있을지도 모릅니다.

그는 “우리는 블랙홀의 복사를 간지럽히는 방식으로 이 블랙홀 중 하나 내부에 영향을…