New Delhi, April 2 – Tuberculosis is one of the world’s deadliest infectious diseases, and now, a team of scientists has discovered a fundamental flaw in a long-standing model of how bacteria control gene expression. This finding could form the basis for innovative strategies to combat tuberculosis and other bacterial infections, according to an official statement released on Thursday.
Scientists previously believed that a protein called ‘σ factor’ binds to RNA polymerase, initiates bacterial transcription, and is then released once the enzyme begins to elongate RNA.
This process, known as the ‘σ-cycle’, was assumed to be universal across bacteria, including TB bacteria.
However, a new study from the Bose Institute, Kolkata, an autonomous institute of the Department of Science and Technology (DST), overturns this assumption.
Researchers Dr. Jayanta Mukhopadhyay and Dr. N. Hazra found that while some σ factors in M. tuberculosis dissociate from RNA polymerase during transcription, others remain firmly attached throughout the process.
Their research, published in the international journal Nucleic Acids Research, reveals that a mechanism taught for decades in molecular biology textbooks – the so-called “universal σ-cycle” – does not apply to all bacteria or all regulatory proteins.
"The study focuses on Mycobacterium tuberculosis, the bacteria that causes tuberculosis (TB), and shows that different σ (sigma) factors, proteins that guide RNA polymerase to specific genes, behave in strikingly different ways during transcription, the first step of gene expression," said the Ministry of Science and Technology.
The discovery that σF remains bound to RNA polymerase suggests a previously unknown mechanism by which the bacterium ensures the sustained expression of stress-response genes, an insight with important implications for TB biology.
Drug-resistant strains pose an increasing global threat to the cure of the disease. M. tuberculosis bacteria survive inside the human host by precisely regulating gene expression under extreme stress conditions.
