Scientists Uncover New RNA Capping Mechanism in Gene Transcription

Research from the Institute of Organic Chemistry and Biochemistry of the CAS in Prague has revealed a previously unknown mechanism governing the genetic transcription process. The team has identified how transcription of genetic information from deoxyribonucleic acid (DNA) to ribonucleic acid (RNA) can be initiated using non-standard RNA caps. Their findings were published in the journal Nature Chemical Biology on January 29, 2026.

Understanding RNA Caps
RNA molecules can undergo various chemical modifications at their ends, termed caps. In eukaryotic organisms, including humans, the most recognized cap is vital for RNA stability and regulation. Recent studies have shown the existence of alternative, non-canonical RNA caps. These include alarmone caps formed by dinucleoside polyphosphate molecules, which help protect cellular RNA during times of stress.

The research team, led by Dr. Hana Cahová, investigated how bacterial RNA polymerase initiates transcription using dinucleoside polyphosphates (NpNs) as opposed to the traditional RNA building blocks. This study marks the first time scientists have described, at an atomic level, the generation of RNA bearing an alarmone cap directly at the start of gene transcription.

Significant Contributions
Key contributions came from Valentina Serianni, who demonstrated the capability of dinucleoside polyphosphates to initiate gene transcription, and Jana Škerlová, who conducted structural analyses of RNA polymerase. By using cryogenic electron microscopy data, Škerlová illustrated how dinucleoside polyphosphate molecules bind within the active site of RNA polymerase, where genetic information is transcribed.

Cahová emphasized the importance of their findings, stating, “We’re describing something that truly occurs in cells and that we’re now able to observe directly at the level of individual molecules. This allows us to answer fundamental questions about cellular processes, such as how cells adapt to stress.”

Cryogenic Electron Microscopy
The use of cryogenic electron microscopy (cryo-EM) was pivotal in the research. Dr. Tomáš Kouba, involved in this aspect of the project, explained, “Cryogenic electron microscopy allows us to freeze biological molecules in a state very close to their natural form and then determine their three-dimensional structure. This makes it possible to look directly into the active centers of enzymes and observe their function down to the atomic level.”

This innovative approach not only sheds light on the mechanisms of gene transcription but also enhances our understanding of how cells respond to stressors such as nutrient deprivation and temperature fluctuations. The discovery of these alarmone caps may have significant implications for future research in cellular biology and genetic regulation.

The research team continues to explore the complexities of RNA modifications, aiming to unravel more secrets of genetic transcription and the broader implications for cellular health and disease.